Subject: The science history timeline

From: [email-masked]
Date: Sun, 20 Mar 1994 17:04:54 +0000

% ------------------------------------
% Science History Timeline Version 3.0
% ------------------------------------
%
% This is a copy of version 3.0 of the science history timeline I
% have been working on. Thanks to the many people who gave me
% suggestions about earlier versions and apologies to those people
% whose suggested additions I have not yet fully incorporated. I'm
% working on them!
%
% The timeline is a plain TEX file and does not require any TEX
% macro files. One should only need to edit out the usenet/mail header
% information and then the file should be able to be passed through
% TEX (you will get some underfull \vbox complaints but these do not
% matter). You do not need to edit out this information and I would
% appreciate it if you would not so that if later you give this file to
% someone else they will be able to send me their ideas. The TEX \vsize
% variable is currently set for British size paper and will have to be
% changed for other sizes of paper.
%
% I would like to make some comments about the timeline:
%
% 1. I realize that scientific discoveries are not clear cut events
%    and that many people often contribute to a scientific discovery
%    while only a few get recognition. I have worked to recognize
%    as many people as possible, but I am sure there are events where I
%    have left out people who deserve credit. I would be grateful if
%    people could point out such instances and suggest corrections so I
%    can implement them in version 3.1.
%
%    I also realize that timelines such as this one are arbitary and will
%    always be infinitely incomplete. Nevertheless, I find this timeline
%    useful and interesting.
%
% 2. I have separated the events into categories since a single list was
%    unwieldly. Such categorization makes my gaps of knowledge in certain
%    fields quite apparent. My poor coverage of some branches of science
%    does not mean that I do not think they are important. I hope to read
%    about and improve my coverage of fields which are poorly covered in
%    this version. To this end, interesting nonspecialist books (preferably
%    written from a historical perspective) would be most helpful and I would
%    appreciate suggestions.
%
%    I would be grateful if people could point out instances where I
%    have put events in the wrong category. I have decided not to cross
%    list events to minimize the length of the timeline.
%
% 3. I would be grateful for factual, name, spelling, and grammar
%    corrections.
%
%    If people have specific events they think should be added to my
%    timeline I would like to know about them. Dates, names, and
%    references (I never add an event until I have read about
%    it and understand it at least qualitatively) would be very useful.
%
% 4. I try to make my explanations of each event as illustrative as
%    possible but restrict each event to three lines maximum since I
%    would like to make it possible for the timeline to be easily
%    browsed. I would be grateful for suggestions as to how to better
%    word specific events so as to make their descriptions maximally
%    illuminating in the available space.
%
% 5. If people know the full names of any of the scientists for which
%    I currently only give initials I would like to know the full names.
%
% Please send any suggestions to me via email.
%
%                                            Thank you,
%
%                                            Niel Brandt
%                                            [email-masked]
%
% This document is copyright Niel Brandt 1994. You are allowed to copy,
% distribute, and edit this document at will without any obligation as long
% as you do not remove the above header. Reproduction and distribution for
% personal profit is not permitted.

%---------------------------------------------------------------------

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\noindent {\tenbf EVENTS IN SCIENCE, MATHEMATICS, AND TECHNOLOGY --- VERSION 3.0}

\vskip 0.05 in
\noindent {\tenrm William Nielsen Brandt --- \tentt [email-masked]}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Classical Mechanics}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-260  & Archimedes mathematically works out the principle of the lever and discovers the principle of buoyancy\cr
60    & Hero of Alexandria writes {\sevenit Metrica}, {\sevenit Mechanics}, and {\sevenit Pneumatics}\cr
1490  & Leonardo da Vinci describes capillary action\cr
1581  & Galileo Galilei notices the timekeeping property of the pendulum\cr
1589  & Galileo Galilei uses balls rolling on inclined planes to show that different weights fall with the same acceleration\cr
1638  & Galileo Galilei publishes {\sevenit Dialogues Concerning Two New Sciences}\cr
1658  & Christian Huygens experimentally discovers that balls placed anywhere inside an inverted cycloid reach the lowest point of the\cr
      & cycloid in the same time and thereby experimentally shows that the cycloid is the isochrone\cr
1668  & John Wallis suggests the law of conservation of momentum\cr
1687  & Isaac Newton publishes his {\sevenit Principia Mathematica}\cr
1690  & James Bernoulli shows that the cycloid is the solution to the isochrone problem\cr
1691  & Johann Bernoulli shows that a chain freely suspended from two points will form a catenary\cr
1691  & James Bernoulli shows that the catenary curve has the lowest center of gravity that any chain hung from two fixed points can have\cr
1696  & Johann Bernoulli shows that the cycloid is the solution to the brachistochrone problem\cr
1714  & Brook Taylor derives the fundamental frequency of a stretched vibrating string in terms of its tension and mass per unit length\cr
      & by solving an ordinary differential equation\cr
1733  & Daniel Bernoulli derives the fundamental frequency and harmonics of a hanging chain by solving an ordinary differential equation\cr
1734  & Daniel Bernoulli solves the ordinary differental equation for the vibrations of an elastic bar clamped at one end\cr
1738  & Daniel Bernoulli examines fluid flow in {\sevenit Hydrodynamica}\cr
1739  & Leonhard Euler solves the ordinary differential equation for a forced harmonic oscillator and notices the resonance phenomenon\cr
1742  & Colin Maclaurin discovers his uniformly rotating self-gravitating spheroids\cr
1747  & Pierre-Louis Moreau de Maupertuis applies minimum principles to mechanics\cr
1759  & Leonhard Euler solves the partial differential equation for the vibration of a rectangular drum\cr
1764  & Leonhard Euler examines the partial differential equation for the vibration of a circular drum and finds one of the Bessel\cr
      & function solutions\cr
1788  & Joseph Lagrange presents Lagrange's equations of motion in {\sevenit M\'ecanique Analytique}\cr
1789  & Antoine Lavoisier states the law of conservation of mass\cr
1821  & William Hamilton begins his analysis of Hamilton's characteristic function\cr
1834  & Carl Jacobi discovers his uniformly rotating self-gravitating ellipsoids\cr
1834  & John Russell observes a nondecaying solitary water wave in the Union Canal near Edinburgh and uses a water tank to study the dependence\cr
      & of solitary water wave velocities on wave amplitude and water depth\cr
1835  & William Hamilton states Hamilton's canonical equations of motion\cr
1835  & Gaspard de Coriolis examines motion on a spinning surface deduces the Coriolis effect\cr
1842  & Christian Doppler examines the Doppler shift of sound\cr
1847  & Hermann Helmholtz formally states the law of conservation of energy\cr
1851  & Jean-Bernard Foucault shows the Earth's rotation with a huge pendulum\cr
1902  & James Jeans finds the length scale required for gravitational pertrubatations to grow in a static nearly homogeneous medium\cr
}

\vskip 0.1 in
\noindent {\sevenbf Electromagnetism and Classical Optics}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

130   & Claudius Ptolemaeus tabulates angles of refraction for several media\cr
1269  & P\`elerin de Maricourt describes magnetic poles and remarks on the nonexistence of isolated magnetic poles\cr
1305  & Dietrich von Freiberg uses crystalline spheres and flasks filled with water to study the reflection and refraction in raindrops that\cr
      & leads to primary and secondary rainbows\cr
1604  & Johannes Kepler describes how the eye focuses light\cr
1611  & Marko Dominis discusses the rainbow in {\sevenit De Radiis Visus et Lucis}\cr
1611  & Johannes Kepler discovers total internal reflection, a small angle refraction law, and thin lens optics\cr
1621  & Willebrord Snell states his law of refraction\cr
1637  & Ren\'e Descartes quantitatively derives the angles at which primary and secondary rainbows are seen with respect to the angle of the\cr
      & Sun's elevation\cr
1657  & Pierre de Fermat introduces the principle of least time into optics\cr
1678  & Christian Huygens states his principle of wavefront sources\cr
1704  & Isaac Newton publishes {\sevenit Opticks}\cr
1728  & James Bradley discovers the aberration of starlight and uses it to determine that the speed of light is about 283,000 km/s\cr
1752  & Benjamin Franklin shows that lightning is electricity\cr
1767  & Joseph Priestly proposes an electrical inverse-square law\cr
1785  & Charles Coulomb introduces the inverse-square law of electrostatics\cr
1786  & Luigi Galvani discovers ``animal electricity'' and postulates that animal bodies are storehouses of electricity\cr
1800  & William Herschel discovers infrared radiation from the Sun\cr
1801  & Johann Ritter discovers ultraviolet radiation from the Sun\cr
1801  & Thomas Young demonstrates the wave nature of light and the principle of interference\cr
1808  & \'Etienne Malus discovers polarization by reflection\cr
1809  & \'Etienne Malus publishes the law of Malus which predicts the light intensity transmitted by two polarizing sheets\cr
1811  & Fran\c cois Arago discovers that some quartz crystals will continuously rotate the electric vector of light\cr
1816  & David Brewster discovers stress birefringence\cr
1818  & Sim\'eon Poisson predicts the Poisson bright spot at the center of the shadow of a circular opaque obstacle\cr
1818  & Fran\c cois Arago verifies the existence of the Poisson bright spot\cr
1820  & Hans Oersted notices that a current in a wire can deflect a compass needle\cr
1825  & Augustin Fresnel phenomenologically explains optical activity by introducing circular birefringence\cr
1826  & Simon Ohm states his law of electrical resistance\cr
1831  & Michael Faraday states his law of induction\cr
1833  & Heinrich Lenz states that an induced current in a closed conducting loop will appear in such a direction that it opposes the change that\cr
      & produced it\cr
1845  & Michael Faraday discovers that light propagation in a material can be influenced by external magnetic fields\cr
1849  & Armand Fizeau and Jean-Bernard Foucault measure the speed of light to be about 298,000 km/s\cr
1852  & George Stokes defines the Stokes parameters of polarization\cr
1864  & James Clerk Maxwell publishes his papers on a dynamical theory of the electromagnetic field\cr
1871  & Lord Rayleigh discusses the blue sky law and sunsets\cr
1873  & James Clerk Maxwell states that light is an electromagnetic phenomenon\cr
1875  & John Kerr discovers the electrically induced birefringence of some liquids\cr
1888  & Heinrich Hertz discovers radio waves\cr
1895  & Wilhelm R\"ontgen discovers X-rays\cr
1896  & Arnold Sommerfeld solves the half-plane diffraction problem\cr
1956  & R. Hanbury-Brown and R.Q. Twiss complete the correlation interferometer\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Thermodynamics, Statistical Mechanics, and Random Processes}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1761  & Joseph Black discovers that ice absorbs heat without changing temperature when melting\cr
1798  & Count Rumford has the idea that heat is a form of energy\cr
1822  & Joseph Fourier formally introduces the use of dimensions for physical quantities in his {\sevenit Theorie Analytique de la Chaleur}\cr
1824  & Sadi Carnot scientifically analyzes the efficiency of steam engines\cr
1827  & Robert Brown discovers the Brownian motion of pollen and dye particles in water\cr
1834  & Benoit-Pierre Clapeyron presents a formulation of the second law of thermodynamics\cr
1843  & James Joule experimentally finds the mechanical equivalent of heat\cr
1848  & Lord Kelvin discovers the absolute zero point of temperature\cr
1852  & James Joule and Lord Kelvin demonstrate that a rapidly expanding gas cools\cr
1859  & James Clerk Maxwell discovers the distribution law of molecular velocities\cr
1870  & Rudolph Clausius proves the scalar virial theorem\cr
1872  & Ludwig Boltzmann states the Boltzmann equation for the temporal development of distribution functions in phase space\cr
1874  & Lord Kelvin formally states the second law of thermodynamics\cr
1876  & Josiah Gibbs begins a two-year long series of papers which discusses phase equilibria, the free energy as the driving force behind chemical\cr
      & reactions, and chemical thermodynamics in general\cr
1879  & Josef Stefan observes that the total radiant flux from a blackbody is proportional to the fourth power of its temperature\cr
1884  & Ludwig Boltzmann derives the Stefan-Boltzmann blackbody radiant flux law from thermodynamic considerations\cr
1888  & Henri-Louis Le Ch\^atelier states that the response of a chemical system perturbed from equilbrium will be to counteract the perturbation\cr
1893  & Wilhelm Wien discovers the displacement law for a blackbody's maximum specific intensity\cr
1905  & Albert Einstein mathematically analyzes the Brownian motion\cr
1906  & Walther Nernst presents a formulation of the third law of thermodynamics\cr
1910  & Albert Einstein and Marian Smoluchowski find the Einstein-Smoluchowski formula for the attenuation coefficient due to density\cr
      & fluctuations in a gas\cr
1916  & Sydney Chapman and David Enskog systematically develop a kinetic theory of gases\cr
1919  & James Jeans discovers that the dynamical constants of motion determine the distribution function for a system of particles\cr
1920  & Meghnad Saha states his ionization equation\cr
1923  & Pieter Debye and Erich H\"uckel publish a statistical treatment of the dissociation of electrolytes\cr
1928  & J.B. Johnson discovers Johnson noise in a resistor\cr
1928  & Harry Nyquist derives the fluctuation-dissipation relationship for a resistor to explain Johnson noise\cr
1942  & J.L. Doob states his theorem on Gaussian-Markoff processes\cr
1957  & A.S. Kompaneets derives his Compton scattering Fokker-Planck equation\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf States of Matter and Phase Transitions}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1895  & Pierre Curie discovers that induced magnetization is proportional to magnetic field strength\cr
1911  & Heike Kammerlingh Onnes discovers superconductivity\cr
1912  & Pieter Debye derives the T-cubed law for the low temperature heat capacity of a nonmetallic solid\cr
1925  & Ernst Ising presents the solution to the one-dimensional Ising model and models ferromagnetism as a cooperative spin phenomenon\cr
1933  & Walter Meissner and R. Ochsenfeld discover perfect superconducting diamagnetism\cr
1942  & Hannes Alfv\'en predicts magnetohydrodynamic waves in plasmas\cr
1944  & Lars Onsager publishes the exact solution to the two-dimensional Ising model\cr
1957  & John Bardeen, Leon Cooper, and Robert Schrieffer develop the BCS theory of superconductivity\cr
1958  & Rudolf M\"ossbauer finds the M\"ossbauer crystal recoil effect\cr
1972  & Douglas Osheroff, Robert Richardson, and David Lee discover that helium-3 can become a superfluid\cr
1974  & Kenneth Wilson develops the renormalization group technique for treating phase transitions\cr
1987  & Alex M\"uller and Georg Bednorz discover high critical temperature ceramic superconductors\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Quantum Mechanics, Molecular Physics, Atomic Physics, Nuclear Physics, and Particle Physics}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-440  & Democritus speculates about fundamental indivisible particles---calls them ``atoms''\cr
1766  & Henry Cavendish discovers and studies hydrogen\cr
1778  & Carl Scheele and Antoine Lavoisier discover that air is composed mostly of nitrogen and oxygen\cr
1781  & Joseph Priestly creates water by igniting hydrogen and oxygen\cr
1800  & William Nicholson and Anthony Carlisle use electrolysis to separate water into hydrogen and oxygen\cr
1803  & John Dalton introduces atomic ideas into chemistry and states that matter is composed of atoms of different weights\cr
1811  & Amedeo Avogadro claims that equal volumes of gases should contain equal numbers of molecules\cr
1832  & Michael Faraday states his laws of electrolysis\cr
1871  & Dmitri Mendeleyev systematically examines the periodic table and predicts the existence of gallium, scandium, and germanium\cr
1873  & Johannes van der Waals introduces the idea of weak attractive forces between molecules\cr
1885  & Johann Balmer finds a mathematical expression for observed hydrogen line wavelengths\cr
1887  & Heinrich Hertz discovers the photoelectric effect\cr
1894  & Lord Rayleigh and William Ramsay discover argon by spectroscopically analyzing the gas left over after nitrogen and oxygen are\cr
      & removed from air\cr
1895  & William Ramsay discovers terrestrial helium by spectroscopically analyzing gas produced by decaying uranium\cr
1896  & Antoine Becquerel discovers the radioactivity of uranium\cr
1896  & Pieter Zeeman studies the splitting of sodium {\sevenit D} lines when sodium is held in a flame between strong magnetic poles\cr
1897  & Joseph Thomson discovers the electron\cr
1898  & William Ramsay and Morris Travers discover neon, krypton, and xenon\cr
1898  & Marie Curie and Pierre Curie isolate and study radium and polonium\cr
1899  & Ernest Rutherford discovers that uranium radiation is composed of positively charged alpha particles and negatively charged beta particles\cr
1900  & Paul Villard discovers gamma-rays while studying uranium decay\cr
1900  & Johannes Rydberg refines the expression for observed hydrogen line wavelengths\cr
1900  & Max Planck states his quantum hypothesis and blackbody radiation law\cr
1902  & Philipp Lenard observes that maximum photoelectron energies are independent of illuminating intensity but depend on frequency\cr
1902  & Theodor Svedberg suggests that fluctuations in molecular bombardment cause the Brownian motion\cr
1905  & Albert Einstein explains the photoelectric effect\cr
1906  & Charles Barkla discovers that each element has a characteristic X-ray and that the degree of penetration of these X-rays is related to\cr
      & the atomic weight of the element\cr
1909  & Hans Geiger and Ernest Marsden discover large angle deflections of alpha particles by thin metal foils\cr
1909  & Ernest Rutherford and Thomas Royds demonstrate that alpha particles are doubly ionized helium atoms\cr
1911  & Ernest Rutherford explains the Geiger-Marsden experiment by invoking a nuclear atom model and derives the Rutherford cross section\cr
1912  & Max von Laue suggests using lattice solids to diffract X-rays\cr
1912  & Walter Friedrich and Paul Knipping diffract X-rays in zinc blende\cr
1913  & William Bragg and Lawrence Bragg work out the Bragg condition for strong X-ray reflection\cr
1913  & Henry Moseley shows that nuclear charge is the real basis for numbering the elements\cr
1913  & Niels Bohr presents his quantum model of the atom\cr
1913  & Robert Millikan measures the fundamental unit of electric charge\cr
1913  & Johannes Stark demonstrates that strong electric fields will split the Balmer spectral line series of hydrogen\cr
1914  & James Franck and Gustav Hertz observe atomic excitation\cr
1914  & Ernest Rutherford suggests that the positively charged atomic nucleus contains protons\cr
1915  & Arnold Sommerfeld develops a modified Bohr atomic model with elliptic orbits to explain relativistic fine structure\cr
1916  & Gilbert Lewis and Irving Langmuir formulate an electron shell model of chemical bonding\cr
1917  & Albert Einstein introduces the idea of stimulated radiation emission\cr
1921  & Alfred Land\'e introduces the Lande g-factor\cr
1922  & Arthur Compton studies X-ray photon scattering by electrons\cr
1922  & Otto Stern and Walter Gerlach show ``space quantization''\cr
1923  & Louis de Broglie suggests that electrons may have wavelike properties\cr
1924  & Wolfgang Pauli states the quantum exclusion principle\cr
1924  & John Lennard-Jones proposes a semiempirical interatomic force law\cr
1924  & Satyendra Bose and Albert Einstein introduce Bose-Einstein statistics\cr
1925  & George Uhlenbeck and Samuel Goudsmit postulate electron spin\cr
1925  & Pierre Auger discovers the Auger autoionization process\cr
1925  & Werner Heisenberg, Max Born, and Pascual Jordan formulate quantum matrix mechanics\cr
1926  & Erwin Schr\"odinger states his nonrelativistic quantum wave equation and formulates quantum wave mechanics\cr
1926  & Erwin Schr\"odinger proves that the wave and matrix formulations of quantum theory are mathematically equivalent\cr
1926  & Oskar Klein and Walter Gordon state their relativistic quantum wave equation\cr
1926  & Enrico Fermi discovers the spin-statistics connection\cr
1926  & Paul Dirac introduces Fermi-Dirac statistics\cr
1927  & Clinton Davission, Lester Germer, and George Thomson confirm the wavelike nature of electrons\cr
1927  & Werner Heisenberg states the quantum uncertainty principle\cr
1927  & Max Born interprets the probabilistic nature of wavefunctions\cr
1928  & Chandrasekhara Raman studies optical photon scattering by electrons\cr
1928  & Paul Dirac states his relativistic electron quantum wave equation\cr
1928  & Charles G. Darwin and Walter Gordon solve the Dirac equation for a Coulomb potential\cr
1929  & Oskar Klein discovers the Klein paradox\cr
1929  & Oskar Klein and Y. Nishina derive the Klein-Nishina cross section for high energy photon scattering by electrons\cr
1929  & N.F. Mott derives the Mott cross section for the Coulomb scattering of relativistic electrons\cr
1930  & Paul Dirac introduces electron hole theory\cr
1930  & Erwin Schr\"odinger predicts the {\sevenit zitterbewegung} motion\cr
1930  & Fritz London explains van der Waals forces as due to the interacting fluctuating dipole moments between molecules\cr
1931  & John Lennard-Jones proposes the Lennard-Jones interatomic potential\cr
1931  & Ir\`ene Joliot-Curie and Fr\'ed\'eric Joliot-Curie observe but misinterpret neutron scattering in parafin\cr
1931  & Wolfgang Pauli puts forth the neutrino hypothesis to explain the apparent violation of energy conservation in beta decay\cr
1931  & Linus Pauling discovers resonance bonding and uses it to explain the high stability of symmetric planar molecules\cr
1931  & Paul Dirac shows that charge conservation can be explained if magnetic monopoles exist\cr
1931  & Harold Urey discovers deuterium using evaporation concentration techniques and spectroscopy\cr
1932  & John Cockcroft and Thomas Walton split lithium and boron nuclei using proton bombardment\cr
1932  & James Chadwick discovers the neutron\cr
1932  & Werner Heisenberg presents the proton-neutron model of the nucleus and uses it to explain isotopes\cr
1932  & Carl Anderson discovers the positron\cr
1933  & Max Delbr\"uck suggests that quantum effects will cause photons to be scattered by an external electric field\cr
1934  & Ir\`ene Joliot-Curie and Fr\'ed\'eric Joliot-Curie bombard aluminum atoms with alpha particles to create artificially radioactive\cr
      & phosphorus-30\cr
1934  & Leo Szilard realizes that nuclear chain reactions may be possible\cr
1934  & Enrico Fermi formulates his theory of beta decay\cr
1934  & Lev Landau tells Edward Teller that nonlinear molecules may have vibrational modes which remove the degeneracy of an orbitally\cr
      & degenerate state\cr
1934  & Enrico Fermi suggests bombarding uranium atoms with neutrons to make a 93 proton element\cr
1934  & Pavel \v Cerenkov reports that light is emitted by relativistic particles traveling in a nonscintillating liquid\cr
1935  & Hideki Yukawa presents a theory of strong interactions and predicts mesons\cr
1935  & Albert Einstein, Boris Podolsky, and Nathan Rosen put forth the EPR paradox\cr
1935  & Niels Bohr presents his analysis of the EPR paradox\cr
1936  & Eugene Wigner develops the theory of neutron absorption by atomic nuclei\cr
1936  & Hans Jahn and Edward Teller present their systematic study of the symmetry types for which the Jahn-Teller effect is expected\cr
1937  & H. Hellmann finds the Hellmann-Feynman theorem\cr
1937  & Seth Neddermeyer, Carl Anderson, J.C. Street, and E.C. Stevenson discover muons using cloud chamber measurements of cosmic rays\cr
1939  & Richard Feynman finds the Hellmann-Feynman theorem\cr
1939  & Otto Hahn and Fritz Strassman bombard uranium salts with thermal neutrons and discover barium among the reaction products\cr
1939  & Lise Meitner and Otto Frisch determine that nuclear fission is taking place in the Hahn-Strassman experiments\cr
1942  & Enrico Fermi makes the first controlled nuclear chain reaction\cr
1942  & Ernst St\"uckelberg introduces the propagator to positron theory and interprets positrons as negative energy electrons moving\cr
      & backwards through spacetime\cr
1943  & Sin-Itiro Tomonaga publishes his paper on the basic physical principles of quantum electrodynamics\cr
1947  & Willis Lamb and Robert Retheford measure the Lamb-Retheford shift\cr
1947  & Cecil Powell, C.M.G. Lattes, and G.P.S. Occhialini discover the pi-meson by studying cosmic ray tracks\cr
1947  & Richard Feynman presents his propagator approach to quantum electrodynamics\cr
1948  & Hendrik Casimir predicts a rudimentary attractive Casimir force on a parallel plate capacitor\cr
1951  & Martin Deutsch discovers positronium\cr
1953  & R. Wilson observes Delbr\"uck scattering of 1.33 MeV gamma-rays by the electric fields of lead nuclei\cr
1954  & Chen Yang and Robert Mills investigate a theory of hadronic isospin by demanding local gauge invariance under isotopic spin space\cr
      & rotations---first non-Abelian gauge theory\cr
1955  & Owen Chamberlain, Emilio Segr\`e, Clyde Wiegand, and Thomas Ypsilantis discover the antiproton\cr
1956  & Frederick Reines and Clyde Cowan detect antineutrinos\cr
1956  & Chen Yang and Tsung Lee propose parity violation by the weak force\cr
1956  & Chien Shiung Wu discovers parity violation by the weak force in decaying cobalt\cr
1957  & Gerhart L\"uders proves the CPT theorem\cr
1957  & Richard Feynman, Murray Gell-Mann, Robert Marshak, and Ennackel Sudarshan propose a V-A Lagrangian for weak interactions\cr
1958  & Marcus Sparnaay experimentally confirms the Casimir effect\cr
1959  & Yakir Aharonov and David Bohm predict the Aharonov-Bohm effect\cr
1960  & R.G. Chambers experimentally confirms the Aharonov-Bohm effect\cr
1961  & Murray Gell-Mann and Yuval Ne'eman discover the Eightfold Way patterns---SU(3) group\cr
1961  & Jeffery Goldstone considers the breaking of global phase symmetry\cr
1962  & Leon Lederman shows that the electron neutrino is distinct from the muon neutrino\cr
1963  & Murray Gell-Mann and George Zweig propose the quark/aces model\cr
1964  & Peter Higgs considers the breaking of local phase symmetry\cr
1964  & J.S. Bell shows that all local hidden variable theories must satisfy Bell's inequality\cr
1964  & Val Fitch and James Cronin observe CP violation by the weak force in the decay of K mesons\cr
1967  & Steven Weinberg puts forth his electroweak model of leptons\cr
1969  & J.C. Clauser, M. Horne, A. Shimony, and R. Holt propose a polarization correlation test of Bell's inequality\cr
1970  & Sheldon Glashow, John Iliopoulos, and Luciano Maiani propose the charm quark\cr
1971  & Gerard 't Hooft shows that the Glashow-Salam-Weinberg electroweak model can be renormalized\cr
1972  & S. Freedman and J.C. Clauser perform the first polarization correlation test of Bell's inequality\cr
1973  & David Politzer proposes the asymptotic freedom of quarks\cr
1974  & Burton Richter and Samuel Ting discover the {\sevenit J}/$\psi$ meson implying the existence of the charm quark\cr
1975  & Martin Perl discovers the tauon\cr
1977  & S.W. Herb finds the upsilon resonance implying the existence of the beauty quark\cr
1982  & A. Aspect, J. Dalibard, and G. Roger perform a polarization correlation test of Bell's inequality that rules out conspiratorial\cr
      & polarizer communication\cr
1983  & Carlo Rubbia, Simon van der Meer, and the CERN UA-1 collaboration find the W$^\pm$ and Z$^0$ intermediate vector bosons\cr
1989  & The Z$^0$ intermediate vector boson resonance width indicates three quark-lepton generations\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Particle Physics Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1896  & Charles Wilson discovers that energetic particles produce droplet tracks in supersaturated gases\cr
1908  & Hans Geiger and Ernest Rutherford invent the Geiger counter\cr
1911  & Charles Wilson finishes a sophisticated cloud chamber\cr
1934  & Ernest Lawrence and Stan Livingston invent the cyclotron\cr
1945  & Edwin McMillan devises a synchrotron\cr
1952  & Donald Glaser develops the bubble chamber\cr
1968  & Georges Charpak and Roger Bouclier build the first multiwire proportional mode particle detection chamber\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Gravitational Physics and Relativity}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1640  & Ismael Bullialdus suggests an inverse-square gravitational force law\cr
1665  & Isaac Newton deduces the inverse-square gravitational force law from the ``falling'' of the Moon\cr
1684  & Isaac Newton proves that planets moving under an inverse-square force law will obey Kepler's laws\cr
1686  & Isaac Newton uses a fixed length pendulum with weights of varying composition to test the weak equivalence principle to 1 part in 1000\cr
1798  & Henry Cavendish measures the gravitational constant\cr
1845  & Urbain Leverrier observes a 35'' per century excess precession of Mercury's orbit\cr
1876  & William Clifford suggests that the motion of matter may be due to changes in the geometry of space\cr
1882  & Simon Newcomb observes a 43'' per century excess precession of Mercury's orbit\cr
1887  & Albert Michelson and Edward Morley do not detect the ether drift\cr
1889  & Roland von E\"otv\"os uses a torsion fiber balance to test the weak equivalence principle to 1 part in one billion\cr
1893  & Ernst Mach states Mach's principle---first constructive attack on the idea of Newtonian absolute space\cr
1905  & Albert Einstein completes his theory of special relativity and states the law of mass-energy conservation\cr
1907  & Albert Einstein introduces the principle of equivalence of gravitation and inertia and uses it to predict the gravitational redshift\cr
1915  & Albert Einstein completes his theory of general relativity\cr
1916  & Albert Einstein shows that the field equations of general relativity admit wavelike solutions\cr
1918  & J. Lense and Hans Thirring find the gravitomagnetic precession of gyroscopes in the equations of general relativity\cr
1919  & Arthur Eddington leads a solar eclipse expedition which claims to detect gravitational deflection of light by the Sun\cr
1921  & T. Kaluza demonstrates that a five-dimensional version of Einstein's equations unifies gravitation and electromagnetism\cr
1937  & Fritz Zwicky states that galaxies could act as gravitational lenses\cr
1937  & Albert Einstein, Leopold Infeld, and Banesh Hoffman show that the geodesic equations of general relativity can be deduced from\cr
      & its field equations\cr
1957  & John Wheeler discusses the breakdown of classical general relativity near singularities and the need for quantum gravity\cr
1960  & Robert Pound and Glen Rebka test the gravitational redshift predicted by the equivalence principle to approximately 1\%\cr
1962  & Robert Dicke, Peter Roll, and R. Krotkov use a torsion fiber balance to test the weak equivalence principle to 2 parts in 100 billion\cr
1964  & Irwin Shapiro predicts a gravitational time delay of radiation travel as a test of general relativity\cr
1965  & Joseph Weber puts the first Weber bar gravitational wave detector into operation\cr
1968  & Irwin Shapiro presents the first detection of the Shapiro delay\cr
1968  & Kenneth Nordtvedt studies a possible violation of the weak equivalence principle for self-gravitating bodies and proposes a new test\cr
      & of the weak equivalence principle based on observing the relative motion of the Earth and Moon in the Sun's gravitational field\cr
1976  & Robert Vessot and Martin Levine use a hydrogen maser clock on a Scout D rocket to test the gravitational redshift predicted by\cr
      & the equivalence principle to approximately 0.007\%\cr
1979  & Dennis Walsh, Robert Carswell, and Ray Weymann discover the gravitationally lensed quasar Q0957+561\cr
1982  & Joseph Taylor and Joel Weisberg show that the rate of energy loss from the binary pulsar PSR1913+16 agrees with that predicted by\cr
      & the general relativistic quadrupole formula to within 5\%\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Black Hole Physics}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1784  & John Michell discusses classical bodies which have escape velocities greater than the speed of light\cr
1795  & Pierre Laplace discusses classical bodies which have escape velocities greater than the speed of light\cr
1916  & Karl Schwarzschild solves the Einstein vacuum field equations for uncharged spherically symmetric systems\cr
1918  & H. Reissner and G. Nordstr\o m solve the Einstein-Maxwell field equations for charged spherically symmetric systems\cr
1923  & George Birkhoff proves that the Schwarzschild spacetime geometry is the unique spherically symmetric solution of the Einstein\cr
      & vacuum field equations\cr
1939  & Robert Oppenheimer and Hartland Snyder calculate the collapse of a pressure-free homogeneous fluid sphere and find that it cuts\cr
      & itself off from communication with the rest of the universe\cr
1963  & Roy Kerr solves the Einstein vacuum field equations for uncharged rotating systems\cr
1964  & Roger Penrose proves that an imploding star will necessarily produce a singularity once it has formed an event horizon\cr
1965  & Ezra Newman, E. Couch, K. Chinnapared, A. Exton, A. Prakash, and Robert Torrence solve the Einstein-Maxwell field equations for\cr
      & charged rotating systems\cr
1968  & Brandon Carter uses Hamilton-Jacobi theory to derive first-order equations of motion for a charged particle moving in the external\cr
      & fields of a Kerr-Newman black hole\cr
1969  & Roger Penrose discusses the Penrose process for the extraction of the spin energy from a Kerr black hole\cr
1969  & Roger Penrose proposes the cosmic censorship hypothesis\cr
1971  & Identification of Cygnus X-1/HDE 226868 as a binary black hole candidate system\cr
1972  & Stephen Hawking proves that the area of a classical black hole's event horizon cannot decrease\cr
1972  & James Bardeen, Brandon Carter, and Stephen Hawking propose four laws of black hole mechanics in analogy with the\cr
      & laws of thermodynamics\cr
1972  & Jacob Bekenstein suggests that black holes have an entropy proportional to their surface area due to information loss effects\cr
1974  & Stephen Hawking applies quantum field theory to black hole spacetimes and shows that black holes will radiate particles with\cr
      & a blackbody spectrum which can cause black hole evaporation\cr
1989  & Identification of GS2023+338/V404 Cygni as a binary black hole candidate system\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Cosmology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1576  & Thomas Digges modifies the Copernican system by removing its outer edge and replacing the edge with a star filled unbounded space\cr
1610  & Johannes Kepler uses the dark night sky to argue for a finite universe\cr
1720  & Edmund Halley puts forth an early form of Olbers' paradox\cr
1744  & Jean-Phillipe de Cheseaux puts forth an early form of Olbers' paradox\cr
1826  & Heinrich Olbers puts forth Olbers' paradox\cr
1917  & Willem de Sitter derives an isotropic static cosmology with a cosmological constant as well as an empty expanding cosmology with a\cr
      & cosmological constant\cr
1922  & Vesto Slipher summarizes his findings on the spiral nebulae's systematic redshifts\cr
1922  & Alexander Friedmann finds a solution to the Einstein field equations which suggests a general expansion of space\cr
1927  & Georges-Henri Lema\^\i tre discusses the creation event of an expanding universe governed by the Einstein field equations\cr
1928  & Harold Robertson briefly mentions that Vesto Slipher's redshift measurements combined with brightness measurements of the same\cr
      & galaxies indicate a redshift-distance relation\cr
1929  & Edwin Hubble demonstrates the linear redshift-distance relation and thus shows the expansion of the universe\cr
1933  & Edward Milne names and formalizes the cosmological principle\cr
1934  & Georges-Henri Lema\^\i tre interprets the cosmological constant as due to a ``vacuum'' energy with an unusual perfect fluid equation of state\cr
1938  & Paul Dirac presents a cosmological theory where the gravitational constant decreases slowly so that the age of the universe divided by the\cr
      & atomic light-crossing time always equals the ratio of the electric force to the gravitational force between a proton and electron\cr
1948  & Ralph Alpher, Hans Bethe, and George Gamow examine element synthesis in a rapidly expanding and cooling universe and suggest that\cr
      & the elements were produced by rapid neutron capture\cr
1948  & Hermann Bondi, Thomas Gold, and Fred Hoyle propose steady state cosmologies based on the perfect cosmological principle\cr
1951  & William McCrea shows that the steady state C-field can be accommodated within general relativity by interpreting it as a\cr
      & contribution to the energy-momentum tensor with an unusual equation of state\cr
1961  & Robert Dicke argues that carbon-based life can only arise when the Dirac large numbers hypothesis is true because this is when burning\cr
      & stars exist---first use of the weak anthropic principle\cr
1963  & Fred Hoyle and Jayant Narlikar show that the steady state theory can explain the isotropy of the universe because deviations from\cr
      & isotropy and homogeneity exponentially decay in time\cr
1964  & Fred Hoyle and Roger Tayler point out that the primordial helium abundance depends on the number of neutrinos\cr
1965  & Martin Rees and Dennis Sciama analyze quasar source count data and discover that the quasar density increases with redshift\cr
1965  & Edward Harrison resolves Olbers' paradox by noting the finite lifetime of stars\cr
1966  & Stephen Hawking and George Ellis show that any plausible general relativistic cosmology is singular\cr
1966  & Jim Peebles shows that the hot Big Bang predicts the correct helium abundance\cr
1967  & Andrey Sakharov presents the requirements for a baryon-antibaryon asymmetry in the universe\cr
1967  & John Bahcall, Wal Sargent, and Maarten Schmidt measure the fine-structure splitting of spectral lines in 3C191 and thereby show that\cr
      & the fine-structure constant does not vary significantly with time\cr
1968  & Brandon Carter speculates that perhaps the fundamental constants of nature must lie within a restricted range to allow the emergence\cr
      & of life---first use of the strong anthropic principle\cr
1969  & Charles Misner formally presents the Big Bang horizon problem\cr
1969  & Robert Dicke formally presents the Big Bang flatness problem\cr
1973  & Edward Tryon proposes that the universe may be a large scale quantum mechanical vacuum fluctuation where positive mass-energy\cr
      & is balanced by negative gravitational potential energy\cr
1974  & Robert Wagoner, William Fowler, and Fred Hoyle show that the hot Big Bang predicts the correct deuterium and lithium abundances\cr
1976  & A.I. Shlyakhter uses samarium ratios from the prehistoric natural fission reactor in Gabon to show that some laws of physics have\cr
      & remained unchanged for over two billion years\cr
1977  & Gary Steigman, David Schramm, and James Gunn examine the relation between the primordial helium abundance and number of neutrinos\cr
      & and claim that at most five lepton families can exist\cr
1980  & Alan Guth proposes the inflationary Big Bang universe as a possible solution to the horizon and flatness problems\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Cosmic Microwave Background Astronomy}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1934  & Richard Tolman shows that blackbody radiation in an expanding universe cools but remains thermal\cr
1941  & Andrew McKellar uses the excitation of CN doublet lines to measure that the ``effective temperature of space'' is about 2.3 K\cr
1948  & George Gamow, Ralph Alpher, and Robert Herman predict that a Big Bang universe will have a blackbody cosmic microwave\cr
      & background with temperature about 5 K\cr
1955  & Tigran Shmaonov finds excess microwave emission with a temperature of roughly 3 K\cr
1964  & A.G. Doroshkevich and Igor Novikov write an unnoticed paper suggesting microwave searches for the blackbody radiation predicted\cr
      & by Gamow, Alpher, and Herman\cr
1965  & Arno Penzias, Robert Wilson, Bernie Burke, Robert Dicke, and James Peebles discover the cosmic microwave background radiation\cr
1966  & Rainer Sachs and Arthur Wolfe theoretically predict microwave background fluctuation amplitudes created by gravitational\cr
      & potential variations between observers and the last scattering surface\cr
1968  & Martin Rees and Dennis Sciama theoretically predict microwave background fluctuation amplitudes created by photons traversing\cr
      & time-dependent potential wells\cr
1969  & R.A. Sunyaev and Yakov Zel'dovich study the inverse Compton scattering of microwave background photons by hot electrons\cr
1990  & The COBE satellite shows that the microwave background has a nearly perfect blackbody spectrum and thereby strongly constrains\cr
      & the density of the intergalactic medium\cr
1992  & The COBE satellite discovers anisotropy in the cosmic microwave background\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Other Background Radiation Fields}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1912  & Victor Hess discovers that the ionization of air increases with altitude indicating the existence of cosmic radiation\cr
1956  & Herbert Friedman detects evidence for extrasolar X-rays\cr
1962  & Riccardo Giacconi, Herbert Gursky, F. Paolini, and Bruno Rossi formally discover the X-ray background\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Galaxies, Clusters of Galaxies, and Large Scale Structure}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1521  & Ferdinand Magellan observes the Magellanic Clouds during his circumnavigating expedition\cr
1750  & Thomas Wright discusses galaxies and the shape of the Milky Way\cr
1845  & Lord Rosse discovers a nebula with a distinct spiral shape\cr
1918  & Harlow Shapley demonstrates that globular clusters surround our galaxy like a halo and are not centered on the Earth\cr
1920  & Harlow Shapely and Heber Curtis debate whether or not the spiral nebulae lie within the Milky Way\cr
1923  & Edwin Hubble resolves the Shapely-Curtis debate by finding Cepheids in Andromeda\cr
1932  & Karl Jansky discovers radio noise from the center of the Milky Way\cr
1933  & Fritz Zwicky applies the virial theorem to the Coma cluster and obtains evidence for unseen mass\cr
1936  & Edwin Hubble introduces the spiral, barred spiral, elliptical, and irregular galaxy classifications\cr
1939  & Grote Reber discovers the radio source Cygnus A\cr
1943  & Carl Seyfert identifies six spiral galaxies with unusually broad emission lines\cr
1949  & J.G. Bolton, G.J. Stanley, and O.B. Slee identify NGC 4486 (M87) and NGC 5128 as extragalactic radio sources\cr
1953  & G\'erard de Vaucouleurs discovers that the galaxies within approximately 200 million light years of the Virgo cluster are\cr
      & confined to a giant supercluster disk\cr
1954  & Walter Baade and Rudolph Minkowski identify the extragalactic optical counterpart of the radio source Cygnus A\cr
1960  & Thomas Matthews determines the radio position of 3C48 to within 5''\cr
1960  & Allan Sandage optically studies 3C48 and observes an unusual blue quasi stellar object\cr
1962  & Cyril Hazard, M.B. Mackey, and A.J. Shimmins use lunar occultations to determine a precise position for 3C273 and deduce that\cr
      & it is a double source\cr
1963  & Maarten Schmidt identifies the redshifted Balmer lines from the quasar 3C273\cr
1973  & Jeremiah Ostriker and James Peebles discover that the amount of visible matter in the disks of typical spiral galaxies is not\cr
      & enough for Newtonian gravitation to keep the disks from flying apart or drastically changing shape\cr
1974  & B.L. Fanaroff and J.M. Riley distinguish between edge-darkened (FR I) and edge-brightened (FR II) radio sources\cr
1976  & Sandra Faber and Robert Jackson discover the Faber-Jackson relation between the luminosity of an elliptical galaxy and the\cr
      & velocity dispersion in its center\cr
1977  & Brent Tully and Richard Fisher discover the Tully-Fisher relation between the luminosity of an isolated spiral galaxy and the\cr
      & velocity of the flat part of its rotation curve\cr
1978  & Steve Gregory and Laird Thompson describe the Coma supercluster\cr
1978  & Vera Rubin, Kent Ford, N. Thonnard, and Albert Bosma measure the rotation curves of several spiral galaxies and find significant\cr
      & deviations from what is predicted by the Newtonian gravitation of visible stars\cr
1981  & Robert Kirshner, August Oemler, Paul Schechter, and Stephen Shectman find evidence for a giant void in Bo\"otes with a diameter\cr
      & of approximately 100 million light years\cr
1985  & Robert Antonucci and J. Miller discover that the Seyfert II galaxy NGC 1068 has broad lines which can only be seen in polarized\cr
      & reflected light\cr
1986  & Amos Yahil, David Walker, and Michael Rowan-Robinson find that the direction of the IRAS galaxy density dipole agrees with the\cr
      & direction of the cosmic microwave background temperature dipole\cr
1987  & David Burstein, Roger Davies, Alan Dressler, Sandra Faber, Donald Lynden-Bell, R.J. Terlevich, and Gary Wegner claim that a\cr
      & large group of galaxies within about 200 million light years of the Milky Way are moving together towards ``The Great Attractor''\cr
1990  & Michael Rowan-Robinson and Tom Broadhurst discover that the IRAS galaxy F10214+4724 is the brightest known object in the universe\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf The Interstellar Medium and Intergalactic Medium}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1848  & Lord Rosse studies M1 and names it the Crab Nebula\cr
1864  & William Huggins studies the spectrum of the Orion Nebula and shows that it is a cloud of gas\cr
1927  & Ira Bowen explains unidentified spectral lines from space as forbidden transition lines\cr
1930  & Robert Trumpler discovers absorption by interstellar dust by comparing the angular sizes and brightnesses of globular clusters\cr
1944  & Hendrik van de Hulst predicts the 21 cm hyperfine line of neutral interstellar hydrogen\cr
1951  & H.I. Ewen and Edward Purcell observe the 21 cm hyperfine line of neutral interstellar hydrogen\cr
1956  & Lyman Spitzer predicts coronal gas around the Milky Way\cr
1965  & James Gunn and Bruce Peterson use observations of the relatively low absorption of the blue component of the Lyman-alpha line\cr
      & from 3C9 to strongly constrain the density and ionization state of the intergalactic medium\cr
1969  & Lewis Snyder, David Buhl, Ben Zuckerman, and Patrick Palmer find interstellar formaldehyde\cr
1970  & Arno Penzias and Robert Wilson find interstellar carbon monoxide\cr
1970  & George Carruthers observes molecular hydrogen in space\cr
1977  & Christopher McKee and Jeremiah Ostriker propose a three component theory of the interstellar medium\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf White Dwarfs, Neutron Stars, and Supernovae}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1054  & Chinese and American Indian astronomers observe the Crab supernova explosion\cr
1572  & Tycho Brahe discovers his supernova in Cassiopeia\cr
1604  & Johannes Kepler's supernova in Serpens is observed\cr
1862  & Alvan Clark observes Sirius B\cr
1866  & William Huggins studies the spectrum of a nova and discovers that it is surrounded by a cloud of hydrogen\cr
1914  & Walter Adams determines an incredibly high density for Sirius B\cr
1926  & Ralph Fowler uses Fermi-Dirac statistics to explain white dwarf stars\cr
1930  & Subrahmanyan Chandrasekhar discovers the white dwarf maximum mass limit\cr
1933  & Fritz Zwicky and Walter Baade propose the neutron star idea and suggest that supernovae might be created by the collapse of\cr
      & normal stars to neutron stars---they also point out that such events can explain the cosmic ray background\cr
1939  & Robert Oppenheimer and George Volkoff calculate the first neutron star models\cr
1942  & J.J.L. Duyvendak, Nicholas Mayall, and Jan Oort deduce that the Crab Nebula is a remnant of the 1054 supernova\cr
      & observed by Chinese astronomers\cr
1958  & Evry Schatzman, Kent Harrison, Masami Wakano, and John Wheeler show that white dwarfs are unstable to inverse beta decay\cr
1962  & Riccardo Giacconi, Herbert Gursky, Frank Paolini, and Bruno Rossi discover Sco X-1\cr
1967  & Jocelyn Bell and Anthony Hewish discover radio pulses from a pulsar\cr
1967  & J.R. Harries, Ken McCracken, R.J. Francey, and A.G. Fenton discover the first X-ray transient (Cen X-2)\cr
1968  & Thomas Gold proposes that pulsars are rotating neutron stars\cr
1969  & David Staelin, E.C. Reifenstein, William Cocke, Mike Disney, and Donald Taylor discover the Crab Nebula pulsar thus connecting\cr
      & supernovae, neutron stars, and pulsars\cr
1971  & Riccardo Giacconi, Herbert Gursky, Ed Kellogg, R. Levinson, E. Schreier, and H. Tananbaum discover 4.8 second X-ray pulsations\cr
      & from Cen X-3\cr
1974  & Russell Hulse and Joseph Taylor discover the binary pulsar PSR1913+16\cr
1977  & Kip Thorne and Anna \.Zytkow present a detailed analysis of Thorne-\.Zytkow objects\cr
1982  & D.C. Backer, Shrinivas Kulkarni, Carl Heiles, M.M. Davis, and Miller Goss discover the millisecond pulsar PSR1937+214\cr
1985  & Michiel van der Klis discovers 30 Hz quasi-periodic oscillations in GX 5-1\cr
1987  & Ian Shelton discovers supernova 1987A in the Large Magellanic Cloud\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Stellar Astronomy}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-134  & Hipparchus creates the magnitude scale of stellar apparent luminosities\cr
1596  & David Fabricus notices that Mira's brightness varies\cr
1672  & Geminiano Montanari notices that Algol's brightness varies\cr
1686  & Gottfried Kirch notices that Chi Cygni's brightness varies\cr
1718  & Edmund Halley discovers stellar proper motions by comparing his astrometric measurements with those of the Greeks\cr
1782  & John Goodricke notices that the brightness variations of Algol are periodic and proposes that it is partially eclipsed by a body\cr
      & moving around it\cr
1784  & Edward Piggot discovers the first Cepheid variable star\cr
1838  & Thomas Henderson, Friedrich Struve, and Friedrich Bessel measure stellar parallaxes\cr
1844  & Friedrich Bessel explains the wobbling motions of Sirius and Procyon by suggesting that these stars have dark companions\cr
1906  & Arthur Eddington begins his statistical study of stellar motions\cr
1908  & Henrietta Leavitt discovers the Cepheid period-luminosity relation\cr
1910  & Ejnar Hertzsprung and Henry Russell study the relation between magnitudes and spectral types of stars\cr
1924  & Arthur Eddington develops the main-sequence mass-luminosity relationship\cr
1929  & George Gamow proposes hydrogen fusion as the energy source for stars\cr
1938  & Hans Bethe and Carl von Weizs\"acker detail the proton-proton chain and CNO cycle in stars\cr
1939  & Rupert Wildt realizes the importance of the negative hydrogen ion for stellar opacity\cr
1952  & Walter Baade distinguishes between Cepheid I and Cepheid II variable stars\cr
1953  & Fred Hoyle predicts a carbon-12 resonance to allow stellar triple alpha reactions at reasonable stellar interior temperatures\cr
1961  & Chushiro Hayashi publishes his work on the Hayashi track of fully convective stars\cr
1963  & Fred Hoyle and William Fowler conceive the idea of supermassive stars\cr
1964  & Subrahmanyan Chandrasekhar and Richard Feynman develop a general relativistic theory of stellar pulsations and show that\cr
      & supermassive stars are subject to a general relativistic instability\cr
1967  & Gerry Neugebauer and Eric Becklin discover the Becklin-Neugebauer object at 10 microns\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Solar Astronomy}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1613  & Galileo Galilei uses sunspot observations to demonstrate the rotation of the Sun\cr
1619  & Johannes Kepler postulates a solar wind to explain the direction of comet tails\cr
1802  & William Wollaston observes dark lines in the solar spectrum\cr
1814  & Joseph Fraunhofer systematically studies the dark lines in the solar spectrum\cr
1834  & Hermann Helmholtz proposes gravitational contraction as the energy source for the Sun\cr
1843  & Heinrich Schwabe announces his discovery of the sunspot cycle and estimates its period to be about ten years\cr
1852  & Edward Sabine shows that sunspot number is correlated with geomagnetic field variations\cr
1859  & Richard Carrington discovers solar flares\cr
1860  & Gustav Kirchoff and Robert Bunsen discover that each element has its own distinct set of spectral lines and use this fact to explain\cr
      & the solar dark lines\cr
1861  & F.G.W. Sp\"orer discovers the variation of sunspot latitudes during a solar cycle\cr
1863  & Richard Carrington discovers the differential nature of solar rotation\cr
1868  & Pierre-Jules-C\'esar Janssen and Norman Lockyer discover an unidentified yellow line in solar prominence spectra and suggest it\cr
      & comes from a new element which they name ``helium''\cr
1893  & Edward Maunder discovers the 1645--1715 Maunder sunspot minimum\cr
1904  & Edward Maunder plots the first sunspot ``butterfly diagram''\cr
1906  & Karl Schwarzschild explains solar limb darkening\cr
1908  & George Hale discovers the Zeeman splitting of spectral lines from sunspots\cr
1942  & J.S. Hey detects solar radio waves\cr
1949  & Herbert Friedman detects solar X-rays\cr
1960  & Robert Leighton, Robert Noyes, and George Simon discover solar five-minute oscillations by observing the Doppler shifts of solar\cr
      & dark lines\cr
1961  & H. Babcock proposes the magnetic coiling sunspot theory\cr
1970  & Roger Ulrich, John Leibacher, and Robert Stein deduce from theoretical solar models that the interior of the Sun could act as a\cr
      & resonant acoustic cavity\cr
1975  & Franz-Ludwig Deubner makes the first accurate measurements of the period and horizontal wavelength of the five-minute solar oscillations\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Solar System Astronomy}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-2136 & Chinese astronomers record a solar eclipse\cr
-586  & Thales of Miletus predicts a solar eclipse\cr
-350  & Aristotle argues for a spherical Earth using lunar eclipses and other observations\cr
-280  & Aristarchus uses the size of the Earth's shadow on the Moon to estimate that the Moon's radius is one-third that of the Earth\cr
-200  & Eratosthenes uses shadows to determine that the radius of the Earth is roughly 6,400 km\cr
-150  & Hipparchus uses parallax to determine that the distance to the Moon is roughly 380,000 km\cr
-134  & Hipparchus discovers the precession of the equinoxes\cr
1512  & Nicholas Copernicus first states his heliocentric theory in {\sevenit Commentariolus}\cr
1543  & Nicholas Copernicus shows that his heliocentric theory simplifies planetary motion tables in {\sevenit De Revolutionibus de Orbium Coelestium}\cr
1577  & Tycho Brahe uses parallax to prove that comets are distant entities and not atmospheric phenomena\cr
1609  & Johannes Kepler states his first two empirical laws of planetary motion\cr
1610  & Galileo Galilei discovers Callisto, Europa, Ganymede, and Io\cr
1610  & Galileo Galilei sees Saturn's rings but does not recognize that they are rings\cr
1619  & Johannes Kepler states his third empirical law of planetary motion\cr
1655  & Giovanni Cassini discovers Jupiter's great red spot\cr
1656  & Christian Huygens identifies Saturn's rings as rings and discovers Titan and the Orion Nebula\cr
1665  & Giovanni Cassini determines the rotational speeds of Jupiter, Mars, and Venus\cr
1672  & Giovanni Cassini discovers Rhea\cr
1672  & Jean Richer and Giovanni Cassini measure the astronomical unit to be about 138,370,000 km\cr
1675  & Ole R\"omer uses the orbital mechanics of Jupiter's moons to estimate that the speed of light is about 227,000 km/s\cr
1705  & Edmund Halley publicly predicts the periodicity of Halley's comet and computes its expected path of return in 1758\cr
1715  & Edmund Halley calculates the shadow path of a solar eclipse\cr
1716  & Edmund Halley suggests a high-precision measurement of the Sun-Earth distance by timing the transit of Venus\cr
1758  & Johann Palitzsch observes the return of Halley's comet\cr
1766  & Johann Titius finds the Titius-Bode rule for planetary distances\cr
1772  & Johann Bode publicizes the Titius-Bode rule for planetary distances\cr
1781  & William Herschel discovers Uranus during a telescopic survey of the northern sky\cr
1796  & Pierre Laplace states his nebular hypothesis for the formation of the solar system from a spinning nebula of gas and dust\cr
1801  & Giuseppe Piazzi discovers the asteroid Ceres\cr
1802  & Heinrich Olbers discovers the asteroid Pallas\cr
1821  & Alexis Bouvard detects irregularities in the orbit of Uranus\cr
1825  & Pierre Laplace completes his study of gravitation, the stability of the solar system, tides, the precession of the equinoxes, the\cr
      & libration of the Moon, and Saturn's rings in {\sevenit M\'ecanique C\'eleste}\cr
1843  & John Adams predicts the existence and location of Neptune from irregularities in the orbit of Uranus\cr
1846  & Urbain Leverrier predicts the existence and location of Neptune from irregularities in the orbit of Uranus\cr
1846  & Johann Galle discovers Neptune\cr
1846  & William Lassell discovers Triton\cr
1849  & Edouard Roche finds the limiting radius of tidal destruction and tidal creation for a body held together only by its self gravity\cr
      & and uses it to explain why Saturn's rings do not condense into a satellite\cr
1856  & James Clerk Maxwell demonstrates that a solid ring around Saturn would be torn apart by gravitational forces and argues that\cr
      & Saturn's rings consist of a multitude of tiny satellites\cr
1866  & Giovanni Schiaparelli realizes that meteor streams occur when the Earth passes through the orbit of a comet that has left debris\cr
      & along its path\cr
1906  & Max Wolf discovers the Trojan asteroid Achilles\cr
1930  & Clyde Tombaugh discovers Pluto\cr
1930  & Seth Nicholson measures the surface temperature of the Moon\cr
1950  & Jan Oort suggests the presence of a cometary Oort cloud\cr
1951  & Gerard Kuiper argues for an annular reservoir of comets between 40--100 astronomical units from the Sun\cr
1977  & James Elliot discovers the rings of Uranus during a stellar occultation experiment on the Kuiper Airborne Observatory\cr
1978  & James Christy discovers Charon\cr
1978  & Peter Goldreich and Scott Tremaine present a Boltzmann equation model of planetary-ring dynamics for indestructible spherical ring\cr
      & particles that do not self-gravitate and find a stability requirement relation between ring optical depth and particle normal\cr
      & restitution coefficient\cr
1988  & Martin Duncan, Thomas Quinn, and Scott Tremaine demonstrate that short-period comets come primarily from the Kuiper Belt and not\cr
      & the Oort cloud\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Astronomical Maps, Catalogs, and Surveys}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-134  & Hipparchus makes a detailed star map\cr
1678  & Edmund Halley publishes a catalog of 341 southern stars---first systematic southern sky survey\cr
1771  & Charles Messier publishes his first list of nebulae\cr
1864  & John Herschel publishes the {\sevenit General Catalog} of nebulae and star clusters\cr
1890  & John Dreyer publishes the {\sevenit New General Catalog} of nebulae and star clusters\cr
1956  & Completion of the Palomar sky survey with the Palomar 48-inch Schmidt optical reflecting telescope\cr
1962  & A.S. Bennett publishes the {\sevenit Revised 3C Catalog} of 328 radio sources\cr
1965  & Gerry Neugebauer and Robert Leighton begin a 2.2 micron sky survey with a 1.6-meter telescope on Mount Wilson\cr
1993  & Start of the 20 cm VLA FIRST survey\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Telescopes, Observatories, and Observing Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1608  & Hans Lippershey tries to patent an optical refracting telescope\cr
1609  & Galileo Galilei builds his first optical refracting telescope\cr
1641  & William Gascoigne invents telescope cross hairs\cr
1661  & James Gregory proposes an optical reflecting telescope\cr
1668  & Isaac Newton constructs the first optical reflecting telescope\cr
1733  & Chester Moor Hall invents the achromatic lens refracting telescope\cr
1758  & John Dolland reinvents the achromatic lens\cr
1789  & William Herschel finishes a 49-inch optical reflecting telescope---located in Slough, England\cr
1840  & J.W. Draper invents astronomical photography and photographs the Moon\cr
1845  & Lord Rosse finishes the Birr Castle 72-inch optical reflecting telescope---located in Parsonstown, Ireland\cr
1872  & Henry Draper invents astronomical spectral photography and photographs the spectrum of Vega\cr
1890  & Albert Michelson proposes the stellar interferometer\cr
1892  & George Hale finishes a spectroheliograph---allows the Sun to be photographed in the light of one element only\cr
1897  & Alvan Clark finishes the Yerkes 40-inch optical refracting telescope---located in Williams Bay, Wisconsin\cr
1917  & Mount Wilson 100-inch optical reflecting telescope begins operation---located in Mount Wilson, California\cr
1930  & Bernard-Ferdinand Lyot invents the coronagraph\cr
1930  & Karl Jansky builds a 30-meter long rotating aerial radio telescope\cr
1933  & Bernard-Ferdinand Lyot invents the Lyot filter\cr
1934  & Bernhard Schmidt finishes the first 14-inch Schmidt optical reflecting telescope\cr
1936  & Palomar 18-inch Schmidt optical reflecting telescope begins operation---located in Palomar, California\cr
1937  & Grote Reber builds a 31-foot radio telescope\cr
1947  & Bernard Lovell and his group complete the Jodrell Bank 218-foot non-steerable radio telescope\cr
1949  & Palomar 48-inch Schmidt optical reflecting telescope begins operation---located in Palomar, California\cr
1949  & Palomar 200-inch optical reflecting telescope begins regular operation---located in Palomar, California\cr
1957  & Bernard Lovell and his group complete the Jodrell Bank 250-foot steerable radio telescope\cr
1957  & Peter Scheuer publishes his {\sevenit P(D)} method for obtaining source counts of spatially unresolved sources\cr
1960  & Martin Ryle tests Earth rotation aperature synthesis\cr
1960  & Owens Valley 27-meter radio telescopes begin operation---located in Big Pine, California\cr
1963  & Arecibo 300-meter radio telescope begins operation---located in Arecibo, Puerto Rico\cr
1964  & Ryle 1-mile radio interferometer begins operation---located in Cambridge, England\cr
1965  & Owens Valley 40-meter radio telescope begins operation---located in Big Pine, California\cr
1967  & First VLBI images---183 km baseline\cr
1969  & Observations start at Big Bear Solar Observatory---located in Big Bear, California\cr
1970  & Cerro Tololo 158-inch optical reflecting telescope begins operation---located in Cerro Tololo, Chile\cr
1970  & Kitt Peak National Observatory 158-inch optical reflecting telescope begins operation---located near Tucson, Arizona\cr
1974  & Anglo-Australian 153-inch optical reflecting telescope begins operation---located in Siding Springs, Australia\cr
1975  & Gerald Smith, Frederick Landauer, and James Janesick use a CCD to observe Uranus---first astronomical CCD observation\cr
1978  & Multiple Mirror 176-inch equivalent optical/infrared reflecting telescope begins operation---located in Amado, Arizona\cr
1979  & UKIRT 150-inch infrared reflecting telescope begins operation---located at Mauna Kea, Hawaii\cr
1979  & Canada-France-Hawaii 140-inch optical reflecting telescope begins operation---located at Mauna Kea, Hawaii\cr
1980  & Completion of construction of the VLA---located in Socorro, New Mexico\cr
1993  & Keck 10-meter optical/infrared reflecting telescope begins operation---located at Mauna Kea, Hawaii\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Artificial Satellites and Space Probes}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1957  & {\sevenit Sputnik I} is launched---first orbiting satellite\cr
1962  & {\sevenit Mariner 2} is the first mission to Venus\cr
1965  & {\sevenit Mariner 4} sends the first clear pictures of Mars\cr
1966  & {\sevenit Luna 10} becomes the first spacecraft to orbit the Moon\cr
1967  & {\sevenit Venera 4} sends the first data from below the clouds of Venus\cr
1967  & The OSO-3 gamma-ray satellite discovers gamma-ray emission from the plane of the Milky Way\cr
1970  & Launch of {\sevenit Uhuru}---first dedicated X-ray satellite\cr
1972  & Launch of the {\sevenit Copernicus} ultraviolet satellite\cr
1974  & {\sevenit Mariner 10} passes by and photographs Mercury\cr
1974  & Launch of the {\sevenit Ariel V} X-ray satellite\cr
1975  & {\sevenit Venera 9} returns the first pictures of the surface of Venus\cr
1976  & {\sevenit Viking I} and {\sevenit Viking II} land on Mars\cr
1976  & The {\sevenit Vela} and ANS X-ray satellites discover X-ray bursts\cr
1976  & The OSO-8 X-ray satellite shows that X-ray bursts have blackbody spectra\cr
1977  & Launch of the HEAO-1 X-ray satellite\cr
1978  & Launch of the {\sevenit International Ultraviolet Explorer} satellite\cr
1978  & Launch of the {\sevenit Einstein} X-ray satellite (HEAO-2)---first X-ray photographs of astronomical objects\cr
1979  & Launch of the {\sevenit Hakucho} X-ray satellite (ASTRO-A)\cr
1979  & Launch of the {\sevenit Ariel VI} cosmic-ray and X-ray satellite\cr
1979  & {\sevenit Voyager 1} and {\sevenit Voyager 2} send back images of Jupiter and its system\cr
1980  & {\sevenit Voyager 1} sends back images of Saturn and its system\cr
1980  & Launch of the {\sevenit Solar Maximum Mission} satellite\cr
1981  & {\sevenit Voyager 2} sends back images of Saturn and its system\cr
1983  & Launch of the EXOSAT X-ray satellite\cr
1983  & Launch of the {\sevenit Tenma} X-ray satellite (ASTRO-B)\cr
1983  & Launch of the IRAS satellite\cr
1986  & {\sevenit Voyager 2} sends back images of Uranus and its system\cr
1987  & Launch of the {\sevenit Ginga} X-ray satellite (ASTRO-C)\cr
1989  & {\sevenit Voyager 2} sends back images of Neptune and its system\cr
1989  & Launch of the {\sevenit Granat} gamma-ray and X-ray satellite\cr
1989  & Launch of the {\sevenit Hipparcos} satellite\cr
1989  & Launch of the COBE satellite\cr
1990  & Launch of the {\sevenit Hubble Space Telescope}\cr
1990  & Launch of the ROSAT X-ray satellite---first imaging X-ray sky survey\cr
1990  & First observations made with {\sevenit Astro-1} (BBXRT, HUT, UIT, WUPPE)\cr
1991  & Launch of the {\sevenit Compton Gamma-Ray Observatory} satellite\cr
1993  & Launch of the {\sevenit Asca} X-ray satellite (ASTRO-D)\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Biology and Organic Chemistry}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-320  & Theophrastus begins the systematic study of botany\cr
1658  & Jan Swammerdam observes red blood cells under a microscope\cr
1663  & Robert Hooke sees cells in cork using a microscope\cr
1668  & Francesco Redi disproves theories of the spontaneous generation of maggots in putrefying matter\cr
1676  & Anton van Leeuwenhoek observes protozoa and calls them ``animalcules''\cr
1677  & Anton van Leeuwenhoek observes spermatazoa\cr
1683  & Anton van Leeuwenhoek observes bacteria\cr
1765  & Lazzaro Spallanzani disproves many theories of the spontaneous generation of cellular life\cr
1771  & Joseph Priestly discovers that plants convert carbon dioxide into oxygen\cr
1798  & Thomas Malthus discusses human population growth and food production in {\sevenit An Essay on the Principle of Population}\cr
1801  & Jean Lamarck begins the detailed study of invertebrate taxonomy\cr
1809  & Jean Lamarck proposes an inheritance of acquired characteristics theory of evolution\cr
1817  & Pierre-Joseph Pelletier and Joseph-Bienaim\'e Caventou isolate chlorophyll\cr
1828  & Karl von Baer discovers the eggs of mammals\cr
1828  & Friedrich W\"ohler synthesizes urea---first synthesis of an organic compound\cr
1836  & Theodor Schwann discovers pepsin in extracts from the stomach lining---first isolation of an animal enzyme\cr
1837  & Theodor Schwann shows that heating air will prevent it from causing putrefaction\cr
1838  & Matthias Schleiden discovers that all living plant tissue is composed of cells\cr
1839  & Theodor Schwann discovers that all living animal tissue is composed of cells\cr
1856  & Louis Pasteur states that microorganisms produce fermentation\cr
1858  & Charles R. Darwin and Alfred Wallace independently propose natural selection theories of evolution\cr
1858  & Rudolf Virchow proposes that cells can only arise from pre-existing cells\cr
1862  & Louis Pasteur convincingly disproves the spontaneous generation of cellular life\cr
1865  & Gregor Mendel presents his experiments on the crossbreeding of pea plants and postulates dominant and recessive factors\cr
1865  & August Kekul\'e realizes that benzene is composed of carbon and hydrogen atoms in a hexagonal ring\cr
1869  & Friedrich Miescher discovers nucleic acids in the nuclei of cells\cr
1874  & Jacobus van't Hoff and Joseph-Achille Le Bel advance a three-dimensional stereochemical representation of organic molecules and\cr
      & propose a tetrahedral carbon atom\cr
1876  & Oskar Hertwig and Hermann Fol show that fertilized eggs possess both male and female nuclei\cr
1884  & Emil Fischer begins his detailed analysis of the compositions and structures of sugars\cr
1898  & Martinus Beijerinck uses filtering experiments to show that tobacco mosaic disease is caused by something smaller than a bacteria\cr
      & which he names a virus\cr
1906  & Mikhail Tsvett discovers the chromatography technique for organic compound separation\cr
1907  & Ivan Pavlov demonstrates conditioned responses with salivating dogs\cr
1907  & Emil Fischer artificially synthesizes peptide amino acid chains and thereby shows that amino acids in proteins are connected by\cr
      & amino group-acid group bonds\cr
1911  & Thomas Morgan proposes that Mendelian factors are arranged in a line on chromosomes\cr
1926  & James Sumner shows that the urease enzyme is a protein\cr
1928  & Otto Diels and Kurt Alder discover the Diels-Alder cycloaddition reaction for forming ring molecules\cr
1929  & Phoebus Levene discovers the sugar deoxyribose in nucleic acids\cr
1929  & Edward Doisy and Adolf Butenandt independently discover estrone\cr
1930  & John Northrop shows that the pepsin enzyme is a protein\cr
1931  & Adolf Butenandt discovers androsterone\cr
1932  & Hans Krebs discovers the urea cycle\cr
1933  & Tadeus Reichstein artificially synthesizes vitamin C---first vitamin synthesis\cr
1935  & Rudolf Schoenheimer uses hydrogen-2 as a tracer to examine the fat storage system of rats\cr
1935  & Wendell Stanley crystallizes the tobacco mosaic virus\cr
1935  & Konrad Lorenz describes the imprinting behavior of young birds\cr
1937  & Theodosius Dobzhansky links evolution and genetic mutation in {\sevenit Genetics and the Origin of Species}\cr
1938  & A living coelacanth is found off the coast of southern Africa\cr
1940  & Donald Griffin and Robert Galambos announce their discovery of sonar echolocation by bats\cr
1942  & Max Delbr\"uck and Salvador Luria demonstrate that bacterial resistance to virus infection is caused by random mutation and not\cr
      & adaptive change\cr
1944  & Oswald Avery shows that DNA carries the genetic code in pneumococci bacteria\cr
1944  & Robert Woodward and William von Eggers Doering synthesize quinine\cr
1948  & Erwin Chargaff shows that in DNA the number of guanine units equals the number of cytosine units and the number of adenine units\cr
      & equals the number of thymine units\cr
1951  & Robert Woodward synthesizes cholesterol and cortisone\cr
1952  & Alfred Hershey and Martha Chase use radioactive tracers to show that DNA is the genetic material in bacteriophage viruses\cr
1952  & Fred Sanger, Hans Tuppy, and Ted Thompson complete their chromatographic analysis of the insulin amino acid sequence\cr
1952  & Rosalind Franklin uses X-ray diffraction to study the structure of DNA and suggests that its sugar-phosphate backbone is on\cr
      & its outside\cr
1953  & James Watson and Francis Crick propose a double helix structure for DNA\cr
1953  & Max Perutz and John Kendrew determine the structure of hemoglobin using X-ray diffraction studies\cr
1953  & Stanley Miller shows that amino acids can be formed when simulated lightning is passed through vessels containing water, methane,\cr
      & ammonia, and hydrogen\cr
1955  & Severo Ochoa discovers RNA polymerase enzymes\cr
1955  & Arthur Kornberg discovers DNA polymerase enzymes\cr
1960  & Juan Or\'o finds that concentrated solutions of ammonium cyanide in water can produce the nucleotide organic base adenine\cr
1960  & Robert Woodward synthesizes chlorophyll\cr
1967  & John Gurden uses nuclear transplantation to clone a clawed frog---first cloning of a vertebrate\cr
1968  & Fred Sanger uses radioactive phosphorous as a tracer to chromatographically decipher a 120 base long RNA sequence\cr
1970  & Hamilton Smith and Daniel Nathans discover DNA restriction enzymes\cr
1970  & Howard Temin and David Baltimore independently discover reverse transcriptase enzymes\cr
1972  & Robert Woodward synthesizes vitamin B-12\cr
1972  & Stephen Jay Gould and Niles Eldredge propose punctuated equilibrium effects in evolution\cr
1974  & Manfred Eigen and Manfred Sumper show that mixtures of nucleotide monomers and RNA-replicase will give rise to RNA molecules which\cr
      & replicate, mutate, and evolve\cr
1974  & Leslie Orgel shows that RNA can replicate without RNA-replicase and that zinc aids this replication\cr
1977  & John Corliss, Jack Dymond, Louis Gordon, John Edmond, Richard von Herzen, Robert Ballard, Kenneth Green, David Williams, Arnold\cr
      & Bainbridge, Kathy Crane, and Tjeerd van Andel discover chemosynthetically based animal communities located around submarine\cr
      & thermal springs on the Gal\'apagos Rift\cr
1977  & Walter Gilbert and Allan Maxam present a rapid gene sequencing technique which uses cloning, base destroying chemicals, and\cr
      & gel electrophoresis\cr
1977  & Fred Sanger and Alan Coulson present a rapid gene sequencing technique which uses dideoxynucleotides and gel electrophoresis\cr
1978  & Fred Sanger presents the 5,386 base sequence for the virus $\phi$X174 --- first sequencing of an entire genome\cr
1983  & Kary Mullis invents the polymerase chain reaction\cr
1984  & Alec Jeffreys devises a DNA fingerprinting method\cr
1985  & Harry Kroto, J.R. Heath, S.C. O'Brien, R.F. Curl, and Richard Smalley discover the unusual stability of the carbon-60\cr
      & Buckminsterfullerine molecule and deduce its structure\cr
1990  & Wolfgang Kr\"atschmer, Lowell Lamb, Konstantinos Fostiropoulos, and Donald Huffman discover that Buckminsterfullerine can be\cr
      & separated from soot because it is soluble in benzene\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Medicine and Medical Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-420  & Hippocrates begins the scientific study of medicine by maintaining that diseases have natural causes\cr
-280  & Herophilus studies the nervous system and distinguishes between sensory nerves and motor nerves\cr
-250  & Erasistratus studies the brain and distinguishes between the cerebrum and cerebellum\cr
50    & Pedanius Dioscorides describes the medical applications of plants in {\sevenit De Materia Medica}\cr
180   & Galen studies the connection between paralysis and severance of the spinal cord\cr
1242  & Ibn an-Naf\=\i s suggests that the right and left ventricles of the heart are separate and describes the lesser circulation of blood\cr
1249  & Roger Bacon writes about convex lens eyeglasses for treating farsightedness\cr
1403  & Venice implements a quarantine against the Black Death\cr
1451  & Nicholas of Cusa invents concave lens spectacles to treat nearsightedness\cr
1543  & Andreas Vesalius publishes {\sevenit De Fabrica Corporis Humani} which corrects Greek medical errors and revolutionizes medicine\cr
1546  & Gerolamo Fracastoro proposes that epidemic diseases are caused by transferable seedlike entities\cr
1553  & Miguel Serveto describes the lesser circulation of blood through the lungs\cr
1559  & Realdo Colombo describes the lesser circulation of blood through the lungs in detail\cr
1603  & Girolamo Fabrici studies leg veins and notices that they have valves which only allow blood to flow toward the heart\cr
1628  & William Harvey explains the vein-artery system and structure of the heart in {\sevenit De Motu Cordis et Sanguinis}\cr
1701  & Giacomo Pylarini gives the first smallpox inoculations\cr
1747  & James Lind discovers that citrus fruits prevent scurvy\cr
1763  & Claudius Aymand performs the first successful appendectomy\cr
1796  & Edward Jenner develops a smallpox vaccination method\cr
1800  & Humphry Davy announces the anaesthetic properties of nitrous oxide\cr
1816  & Rene Laennec invents the stethoscope\cr
1842  & Crawford Long performs the first surgical operation using anasthesia\cr
1847  & Ignaz Semmelweis studies and prevents the transmission of puerperal fever\cr
1870  & Louis Pasteur and Robert Koch establish the germ theory of disease\cr
1881  & Louis Pasteur develops an anthrax vaccine\cr
1882  & Louis Pasteur develops a rabies vaccine\cr
1890  & Emil von Behring discovers antitoxins and uses them to develop tetanus and diptheria vaccines\cr
1906  & Frederick Hopkins suggests the existence of vitamins and suggests that a lack of vitamins causes scurvy and rickets\cr
1907  & Paul Ehrlich develops a chemotheraputic cure for sleeping sickness\cr
1921  & Edward Mellanby discovers vitamin D and shows that its absence causes rickets\cr
1928  & Alexander Fleming discovers penicillin\cr
1932  & Gerhard Domagk develops a chemotheraputic cure for streptococcus\cr
1952  & Jonas Salk develops the first polio vaccine\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Pure and Applied Mathematics}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-1700 & Egyptian mathematicians employ primitive fractions\cr
-530  & Pythagoras studies propositional geometry and vibrating lyre strings\cr
-370  & Eudoxus states the method of exhaustion for area determination\cr
-350  & Aristotle discusses logical reasoning in {\sevenit Organon}\cr
-300  & Euclid studies geometry as an axiomatic system in {\sevenit Elements} and states the law of reflection in {\sevenit Catoptrics}\cr
-260  & Archimedes computes $\pi$ to two decimal places using inscribed and cirumscribed polygons and computes the area under a parabolic segment\cr
-200  & Apollonius writes {\sevenit On Conic Sections} and names the ellipse, parabola, and hyperbola\cr
250   & Diophantus writes {\sevenit Arithmetica}, the first systematic treatise on algebra\cr
450   & Tsu Ch'ung-Chih and Tsu K\^eng-Chih compute $\pi$ to six decimal places\cr
550   & Hindu mathematicians give zero a numeral representation in a positional notation system\cr
1202  & Leonardo Fibonacci demonstrates the utility of Arabic numerals in his {\sevenit Book of the Abacus}\cr
1424  & Ghiy\=ath al-K\=ash\=\i\ computes $\pi$ to sixteen decimal places using inscribed and cirumscribed polygons\cr
1520  & Scipione Ferro develops a method for solving cubic equations\cr
1535  & Niccol\`o Tartaglia develops a method for solving cubic equations\cr
1540  & Lodovico Ferrari solves the quartic equation\cr
1596  & Ludolf van Ceulen computes $\pi$ to twenty decimal places using inscribed and cirumscribed polygons\cr
1614  & John Napier discusses Napierian logarithms in {\sevenit Mirifici Logarithmorum Canonis Descriptio}\cr
1617  & Henry Briggs discusses decimal logarithms in {\sevenit Logarithmorum Chilias Prima}\cr
1619  & Ren\'e Descartes discovers analytical geometry\cr
1629  & Pierre de Fermat develops a rudimentary differential calculus\cr
1634  & G.P. de Roberval shows that the area under a cycloid is three times the area of its generating circle\cr
1637  & Pierre de Fermat claims to have proven Fermat's Last Theorem in his copy of Diophantus' {\sevenit Arithmetica}\cr
1654  & Blaise Pascal and Pierre de Fermat create the theory of probability\cr
1655  & John Wallis writes {\sevenit Arithmetica Infinitorum}\cr
1658  & Christopher Wren shows that the length of a cycloid is four times the diameter of its generating circle\cr
1665  & Isaac Newton invents his calculus\cr
1668  & Nicholas Mercator and William Brouncker discover an infinite series for the logarithm while attempting to calculate the area under a\cr
      & hyperbolic segment\cr
1671  & James Gregory discovers the series expansion for the inverse-tangent function\cr
1673  & Gottfried Leibniz invents his calculus\cr
1675  & Isaac Newton invents an algorithm for the computation of functional roots\cr
1691  & Gottfried Leibniz discovers the technique of separation of variables for ordinary differential equations\cr
1693  & Edmund Halley prepares the first mortality tables statistically relating death rate to age\cr
1696  & Guillaume de L'H\^opital states his rule for the examination of indeterminate forms\cr
1706  & John Machin develops a quickly converging inverse-tangent series for $\pi$ and computes $\pi$ to 100 decimal places\cr
1712  & Brook Taylor develops Taylor series'\cr
1722  & Abraham De Moivre states De Moivre's theorem\cr
1724  & Abraham De Moivre studies mortality statistics and the foundation of the theory of annuities in {\sevenit Annuities on Lives}\cr
1730  & James Stirling publishes {\sevenit The Differential Method}\cr
1733  & Geralamo Saccheri studies what geometry would be like if Euclid's fifth postulate were false\cr
1734  & Leonhard Euler introduces the integrating factor technique for solving first order ordinary differential equations\cr
1736  & Leonhard Euler solves the Koenigsberg bridge problem\cr
1739  & Leonhard Euler solves the general homogeneous linear ordinary differential equation with constant coefficients\cr
1742  & Christian Goldbach conjectures that every even number greater than two can be expressed as the sum of two primes\cr
1744  & Leonhard Euler shows the existence of transcendental numbers\cr
1748  & Maria Agnesi discusses analysis in {\sevenit Instituzioni Analitiche ad Uso della Gioventu Italiana}\cr
1761  & Thomas Bayes proves Bayes' theorem\cr
1796  & Karl Gauss presents a method for constructing a heptadecagon using only a compass and straightedge and also shows that only\cr
      & polygons with certain numbers of sides can be constructed\cr
1797  & Caspar Wessel associates vectors with complex numbers and studies complex number operations in geometrical terms\cr
1799  & Karl Gauss proves that every polynomial equation has a solution among the complex numbers\cr
1806  & Jean-Robert Argand associates vectors with complex numbers and studies complex number operations in geometrical terms\cr
1807  & Joseph Fourier first announces his discoveries about the trigonometric decomposition of functions\cr
1811  & Karl Gauss discusses the meaning of integrals with complex limits and briefly examines the dependence of such integrals on\cr
      & the chosen path of integration\cr
1815  & Sim\'eon Poisson carries out integrations along paths in the complex plane\cr
1817  & Bernard Bolzano presents Bolzano's theorem---a continuous function which is negative at one point and positive at another\cr
      & point must be zero for at least one point in between\cr
1824  & Niels Abel partially proves that the general quintic or higher equations do not have algebraic solutions\cr
1822  & Augustin-Louis Cauchy presents the Cauchy integral theorem for integration around the boundary of a rectangle\cr
1825  & Augustin-Louis Cauchy presents the Cauchy integral theorem for general integration paths---he assumes the function being\cr
      & integrated has a continuous derivative\cr
1825  & Augustin-Louis Cauchy introduces the theory of residues\cr
1825  & Peter Dirichlet and Adrien Legendre prove Fermat's Last Theorem for n=5\cr
1828  & George Green proves Green's theorem\cr
1829  & Nikolai Lobachevski publishes his work on hyperbolic non-Euclidean geometry\cr
1832  & \'Evariste Galois presents a general condition for the solvability of algebraic equations\cr
1832  & Peter Dirichlet proves Fermat's Last Theorem for n=14\cr
1837  & Pierre Wantsel proves that doubling the cube and trisecting the angle are impossible with only a compass and straightedge\cr
1841  & Karl Weierstrass discovers but does not publish the Laurent expansion theorem\cr
1843  & Pierre-Alphonse Laurent discovers and presents the Laurent expansion theorem\cr
1843  & William Hamilton discovers the calculus of quaternions and deduces that they are non-commutative\cr
1847  & George Boole formalizes symbolic logic in {\sevenit The Mathematical Analysis of Logic}\cr
1849  & George Stokes shows that solitary waves can arise from a combination of periodic waves\cr
1850  & Alexandre Puiseux distinguishes between poles and branch points and introduces the concept of essential singular points\cr
1850  & George Stokes proves Stokes' theorem\cr
1854  & Bernhard Riemann introduces Riemannian geometry\cr
1854  & Arthur Cayley shows that quaternions can be used to represent rotations in four-dimensional space\cr
1858  & August M\"obius invents the M\"obius strip\cr
1870  & Felix Klein constructs an analytic geometry for Lobachevski's geometry thereby establishing its self-consistency and the logical\cr
      & independence of Euclid's fifth postulate\cr
1873  & Charles Hermite proves that {\sevenit e} is transcendental\cr
1878  & Charles Hermite solves the general quintic equation by means of elliptic and modular functions\cr
1873  & Georg Frobenius presents his method for finding series solutions to linear differential equations with regular singular points\cr
1882  & Ferdinand Lindeman proves that $\pi$ is transcendental and that the circle cannot be squared with a compass and straightedge\cr
1882  & Felix Klein invents the Klein bottle\cr
1895  & Diederik Korteweg and Gustav de Vries derive the KdV equation to describe the development of long solitary water waves in a\cr
      & canal of rectangular cross section\cr
1896  & Jacques Hadamard and Charles de La Vall\'ee-Poussin independently prove the prime number theorem\cr
1899  & David Hilbert presents a set of self-consistent geometric axioms in {\sevenit Foundations of Geometry}\cr
1900  & David Hilbert states his list of 23 problems which show where further mathematical work is needed\cr
1901  & \'Elie Cartan develops the exterior derivative\cr
1903  & C. Runge presents a fast Fourier transform algorithm\cr
1908  & Ernst Zermelo axiomatizes set theory\cr
1912  & L.E.J. Brouwer presents the Brouwer fixed-point theorem\cr
1914  & Srinivasa Ramanujan publishes {\sevenit Modular Equations and Approximations to $\pi$}\cr
1928  & John von Neumann begins devising the principles of game theory and proves the minimax theorem\cr
1930  & Casimir Kuratowski shows that the three cottage problem has no solution\cr
1931  & Kurt G\"odel shows that mathematical systems are not fully self-contained\cr
1933  & Karol Borsuk and Stanislaw Ulam present the Borsuk-Ulam antipodal-point theorem\cr
1942  & G.C. Danielson and Cornelius Lanczos develop a fast Fourier transform algorithm\cr
1943  & Kenneth Levenberg proposes a method for nonlinear least squares fitting\cr
1948  & John von Neumann mathematically studies self-reproducing machines\cr
1949  & John von Neumann computes $\pi$ to 2,037 decimal places using ENIAC\cr
1950  & Stanislaw Ulam and John von Neumann present cellular automata dynamical systems\cr
1953  & Nicholas Metropolis introduces the idea of thermodynamic simulated annealing algorithms\cr
1955  & Enrico Fermi, John Pasta, and Stanislaw Ulam numerically study a nonlinear spring model of heat conduction and discover solitary wave\cr
      & type behavior\cr
1960  & C.A.R. Hoare invents the quicksort algorithm\cr
1960  & Irving Reed and Gustave Solomon present the Reed-Solomon error-correcting code\cr
1961  & Daniel Shanks and John Wrench compute $\pi$ to 100,000 decimal places using an inverse-tangent identity and an IBM-7090 computer\cr
1962  & Donald Marquardt proposes the Levenberg-Marquardt nonlinear least squares fitting algorithm\cr
1963  & Martin Kruskal and Norman Zabusky analytically study the Fermi-Pasta-Ulam heat conduction problem in the continuum limit and find\cr
      & that the KdV equation governs this system\cr
1965  & Martin Kruskal and Norman Zabusky numerically study colliding solitary waves in plasmas and find that they do not disperse after collisions\cr
1965  & James Cooley and John Tukey present an influential fast Fourier transform algorithm\cr
1966  & E.J. Putzer presents two methods for computing the exponential of a matrix in terms of a polynomial in that matrix\cr
1976  & Kenneth Appel and Wolfgang Haken use a computer to solve the four-color problem\cr
1983  & Gerd Faltings proves the Mordell Conjecture and thereby shows that there are only finitely many whole number solutions for each\cr
      & exponent of Fermat's Last Theorem\cr
1985  & Louis de Branges proves the Bieberbach Conjecture\cr
1987  & Yasumasa Kanada, David Bailey, Jonathan Borwein, and Peter Borwein use iterative modular equation approximations to elliptic\cr
      & integrals and a NEC SX-2 supercomputer to compute $\pi$ to 134 million decimal places\cr
1993  & Andrew Wiles proves part of the Taniyama-Shimura Conjecture and thereby proves Fermat's Last Theorem\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Geology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1620  & Francis Bacon notices the jigsaw fit of the opposite shores of the Atlantic Ocean\cr
1701  & Edmund Halley suggests using the salinity and evaporation of the Mediterranean to determine the age of the Earth\cr
1837  & Louis Agassiz begins his glaciation studies which eventually demonstrate that the Earth has had at least one Ice Age\cr
1862  & Lord Kelvin attempts to find the age of the Earth by examining its cooling time and estimates that the Earth is\cr
      & between 20--400 million years old\cr
1903  & George Darwin and John Joly claim that radioactivity is partially responsible for the Earth's heat\cr
1907  & Bertram Boltwood proposes that the amount of lead in uranium and thorium ores might be used to determine the Earth's\cr
      & age and crudely dates some rocks to have ages between 410--2200 million years\cr
1912  & Alfred Wegener proposes that all the continents once formed a single landmass called Pangaea that broke apart via\cr
      & continental drift\cr
1913  & Albert Michelson measures tides in the solid body of the Earth\cr
1935  & Charles Richter invents a logarithmic scale to measure the intensity of earthquakes\cr
1953  & Maurice Ewing and Bruce Heezen discover the Great Global Rift running along the Mid-Oceanic Ridge\cr
1960  & Harry Hess proposes that new sea floor might be created at mid-ocean rifts and destroyed at deep sea trenches\cr
1963  & F.J. Vine and D.H. Matthews explain the stripes of magnetized rocks with alternating magnetic polarities running\cr
      & parallel to mid-ocean ridges as due to sea floor spreading and the periodic geomagnetic field reversals\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Geography, Meteorology, Paleontology, Science Philosophy, and Science Publishing}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

25    & Pomponius Mela formalizes the climatic zone system\cr
1569  & Gerardus Mercator issues the first Mercator projection map\cr
1620  & Francis Bacon analyzes the scientific method in his {\sevenit Great Instauration of Learning}\cr
1686  & Edmund Halley presents a systematic study of the trade winds and monsoons and identifies solar heating as the cause of\cr
      & atmospheric motions\cr
1686  & Edmund Halley establishes the relationship between barometric pressure and height above sea level\cr
1716  & Edmund Halley suggests that aurorae are caused by ``magnetic effluvia'' moving along the Earth's magnetic field lines\cr
1822  & Gideon Mantell discovers the fossilized skeleton of an iguanodon dinosaur\cr
1869  & Joseph Lockyer starts the scientific journal {\sevenit Nature}\cr
1909  & Discovery of the Burgess Shale Cambrian fossil site\cr
1920  & Andrew Douglass proposes dendrochronology dating\cr
1920  & Milutin Milankovich proposes that long term climatic cycles may be due to changes in the eccentricity of the Earth's orbit and\cr
      & changes in the Earth's obliquity\cr
1947  & Willard Libby introduces carbon-14 dating\cr
1949  & Edward Murphy states his law\cr
1974  & Donald Johanson and Tom Gray discover a 3.5 million-year-old female hominid fossil that is 40\% complete and name it ``Lucy''\cr
1980  & Luis Alvarez, Walter Alvarez, Frank Asaro, and Helen Michel propose that a giant comet or asteroid may have struck the Earth\cr
      & approximately 65 million years ago thereby causing massive extinctions and enriching the iridium in the K-T layer\cr
1984  & Hou Xianguang discovers the Chengjiang Cambrian fossil site\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Agriculture and Food Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-1800 & Fermentation of dough, grain, and fruit juices is discovered\cr
600   & The moldboard plow is invented in eastern Europe\cr
850   & Coffee is invented in Arabia\cr
1300  & Arnau de Villanova develops alcohol distillation\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Clothing and Textiles Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1733  & John Kay patents the flying shuttle loom\cr
1764  & James Hargreaves invents the spinning jenny\cr
1794  & Eli Whitney patents the cotton gin\cr
1801  & Joseph-Marie Jacquard invents the Jacquard punched card loom\cr
1856  & William Perkin invents the first synthetic dye\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Motor and Engine Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1698  & Thomas Savery builds a steam-powered water pump for pumping water out of mines\cr
1712  & Thomas Newcomen builds a piston-and-cylinder steam-powered water pump for pumping water out of mines\cr
1769  & James Watt patents his first improved steam engine\cr
1821  & Michael Faraday builds an electricity-powered motor\cr
1876  & Nikolaus Otto designs a four-stroke internal-combustion engine\cr
1888  & Nikola Tesla patents the induction motor\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Transportation Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-3500 & Wheeled carts are invented\cr
-3500 & River boats are invented\cr
-2000 & Horses are tamed and used for transport\cr
770   & Iron horseshoes come into common use\cr
1492  & Leonardo da Vinci describes a flying machine\cr
1662  & Blaise Pascal invents a horse-drawn public bus which has a regular route, schedule, and fare system\cr
1740  & Jacques de Vaucanson demonstrates his clockwork powered carriage\cr
1783  & Joseph Montgolfier and \'Etienne Montgolfier launch the first hot air balloons\cr
1801  & Richard Trevithick builds a prototype steam powered railroad locomotive\cr
1807  & Isaac de Rivas makes a hydrogen gas powered vehicle\cr
1814  & George Stephenson builds the first practical steam powered railroad locomotive\cr
1862  & Jean Lenoir makes a gasoline-engine automobile\cr
1868  & George Westinghouse invents the compressed air locomotive brake\cr
1900  & Ferdinand von Zeppelin builds the first successful dirigible\cr
1903  & Orville Wright and Wilbur Wright fly the first motor-driven airplane\cr
1908  & Henry Ford develops the assembly line method of automobile manufacturing\cr
1947  & First supersonic flight\cr
1969  & First manned mission to the Moon\cr
1981  & First flight of the space shuttle\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Underwater Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1716  & Edmund Halley builds a diving bell\cr
1801  & Robert Fulton builds the first submarine\cr
1819  & Augustus Siebe invents a diving suit which receives air pumped down from the surface\cr
1934  & Charles Beebe dives to 3,028 feet using a bathysphere\cr
1943  & Jacques-Yves Cousteau makes the first dive with a compressed-air aqualung\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Communication Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-3500 & The Sumerians develop cuneiform writing and the Egyptians develop hieroglyphic writing\cr
-1500 & The Phoenicians develop an alphabet\cr
-170  & Parchment is discovered in Pergamum\cr
105   & Tsai Lun invents paper\cr
350   & The Chinese develop a method for printing pages using symbols carved on a wooden block\cr
1450  & The Chinese develop wooden block movable type printing\cr
1454  & Johannes Gutenberg finishes a printing press with metal movable type\cr
1793  & Claude Chappe establishes the first long-distance semaphore telegraph line\cr
1831  & Joseph Henry proposes and builds an electric telegraph\cr
1835  & Samuel Morse develops the Morse code\cr
1843  & Samuel Morse builds the first long distance electric telegraph line\cr
1876  & Alexander Graham Bell and Thomas Watson exhibit an electric telephone\cr
1877  & Thomas Edison patents the phonograph\cr
1889  & Almon Strowger patents the direct dial telephone\cr
1901  & Guglielmo Marconi transmits radio signals from Cornwall to Newfoundland\cr
1925  & John Baird transmits the first television signal\cr
1958  & Chester Carlson presents the first photocopier suitable for office use\cr
1966  & Charles Kao realizes that silica-based waveguides offer a practical way to transmit light via total internal reflection\cr
1973  & Akira Hasegawa and Fred Tappert propose the use of solitary waves to carry information in optical fibers\cr
1977  & Donald Knuth begins work on \TeX \cr
1980  & Linn Mollenauer, Rogers Stollen, and James Gordon demonstrate that solitary waves can be propagated through optical fibers\cr
1991  & Anders Olsson transmits solitary waves through an optical fiber with a data rate of 32 billion bits per second\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Photography Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1826  & Joseph Ni\'epce takes the first permanent photograph\cr
1891  & Thomas Edison patents the ``kinetoscopic camera''\cr
1973  & Fairchild Semiconductor releases the first large image forming CCD chip---100 rows and 100 columns\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Calculator and Computer Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1617  & John Napier discusses the Napier's bones calculating method in {\sevenit Rabdologia}\cr
1622  & William Oughtred invents the slide rule\cr
1623  & Wilhelm Schickard builds his 6-digit ``Calculating Clock'' that can add and subtract\cr
1645  & Blaise Pascal completes his 5-digit ``Pascaline'' that can add\cr
1930  & Vannevar Bush builds a partly electronic computer capable of solving differential equations\cr
1946  & Presper Eckert and John Mauchly announce ENIAC, the first practical entirely electronic computer\cr
1948  & William Shockley, Walter Brattain, and John Bardeen invent the transistor\cr
1950  & Alan Turing proposes the ``Turing test'' criterion for an intelligent machine\cr
1951  & Presper Eckert and John Mauchly finish UNIVAC I, the first mass-produced electronic computer\cr
1971  & Texas Instruments releases the first easily portable electronic calculator\cr
1977  & Apple Computer releases the Apple II personal computer\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Time Measurement Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-270  & Ctesibius builds a popular water clock\cr
-46   & Julius Caesar and Sosigenes develop a solar calendar with leap years\cr
1502  & Peter Henlein builds the first pocketwatch\cr
1582  & Pope Gregory XIII, Aloysius Lilius, and Christopher Clavius introduce a Gregorian calendar with an improved leap year system\cr
1656  & Christian Huygens builds the first accurate pendulum clock\cr
1737  & John Harrison presents the first stable nautical chronometer, thereby allowing for precise longitude determination while at sea\cr
1928  & Joseph Horton and Warren Morrison build the first quartz crystal oscillator clock\cr
1946  & Felix Bloch and Edward Purcell develop nuclear magnetic resonance\cr
1949  & Harold Lyons develops an atomic clock based on the quantum mechanical vibrations of the ammonia molecule\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Temperature and Pressure Measurement Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1592  & Galileo Galilei builds a crude thermometer using the contraction of air to draw water up a tube\cr
1643  & Evangelista Torricelli invents the mercury barometer\cr
1714  & Gabriel Fahrenheit invents the mercury in glass thermometer\cr
1864  & Antoine Becquerel suggests an optical pyrometer\cr
1892  & Henri-Louis Le Ch\^atelier builds the first optical pyrometer\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Microscope Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1590  & Zacharias Janssen invents the microscope\cr
1674  & Anton van Leeuwenhoek invents the compound microscope\cr
1932  & Ernst Ruska builds the first electron microscope\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Low Temperature Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1891  & Z.F. Wroblewski condenses experimentally useful quantities of liquid air\cr
1892  & James Dewar invents the vacuum-insulated, silver-plated glass Dewar\cr
1908  & Heike Kammerlingh Onnes liquifies helium\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Rocket and Missile Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

1926  & Robert Goddard launches the first liquid fuel rocket\cr
1944  & Wernher von Braun and Walter Dornberger launch the first V2 rocket\cr
1958  & Launch of the first ICBM\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Materials Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-4000 & Copper metallurgy is invented and copper is used for ornamentation\cr
-3000 & Bronze is used for weapons and armor\cr
-1500 & The Hittites develop crude iron metallurgy\cr
-1200 & Invention of steel when iron and charcoal are combined properly\cr
700   & Porcelain is invented in China\cr
1839  & Charles Goodyear invents vulcanized rubber\cr
1909  & Leo Baekeland presents the Bakelite hard thermosetting plastic\cr
1931  & Julius Nieuwland develops the synthetic rubber neoprene\cr
1931  & Wallace Carothers develops nylon\cr
1953  & Karl Ziegler discovers metallic catalysts which greatly improve the strength of polyethylene polymers\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf Lighting Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-3000 & Candles are invented\cr
1815  & Humphry Davy invents the miner's safety lamp\cr
1879  & Thomas Edison patents the carbon-thread incandescent lamp\cr
}

%---------------------------------------------------------------------

\vskip 0.1 in
\noindent {\sevenbf General Technology}
\vskip 0.05 in

\halign{

# & \hskip 0.040in \hbox{#}\cr

-7000 & Pottery is invented\cr
-700  & Invention of aqueducts\cr
-640  & Invention of coins\cr
-400  & Catapults are invented in Syracuse\cr
-150  & Hipparchus invents the astrolabe\cr
-100  & Glass-blowing is discovered in Syria\cr
700   & Windmills are invented in Persia\cr
1050  & Crossbows are invented in France\cr
1249  & Roger Bacon states formulas for gunpowder\cr
1346  & Cannon come into wide use\cr
1480  & Martin Behaim introduces the nautical astrolabe\cr
1480  & Leonardo da Vinci describes a workable parachute\cr
1645  & Otto von Guericke builds the first vacuum pump\cr
1731  & John Hadley invents the sextant\cr
1800  & Alessandro Volta announces his invention of the electric battery\cr
1823  & William Sturgeon invents the electromagnet\cr
1840  & Justus von Liebig invents artificial fertilizer\cr
1867  & Alfred Nobel patents dynamite\cr
1880  & John Milne invents the seismograph\cr
1885  & William Stanley invents the alternating current transformer\cr
1903  & Konstantin Tsiolkovsky begins a series of papers discussing the use of rocketry to reach outer space, space suits, and\cr
      & colonization of the solar system\cr
1917  & Paul Langevin develops a sonar echolocation system\cr
1925  & Theodor Svedberg develops the ultra-centrifuge, thereby revolutionizing the determination of molecular weights\cr
1935  & Robert Watson-Watt devises a microwave radar\cr
1945  & First nuclear fission bomb exploded at the Trinity test site, about sixty miles northwest of Alamogordo, New Mexico\cr
1952  & First thermonuclear fusion bomb exploded\cr
1952  & Wernher von Braun discusses the technical details of a manned exploration of Mars in {\sevenit The Mars Project}\cr
1953  & Charles Townes makes the first maser\cr
1954  & Construction of the first nuclear power reactor\cr
1960  & Theodore Maiman makes the first laser\cr
}

%---------------------------------------------------------------------

\end