21st Congress.] 

No. 417. 

[1st Session.



March 27, 1830.

To the House of Representatives:

Gentlemen: I transmit, for the consideration of Congress, a letter of the Secretary of the Navy, accompanying the report of Lieutenants Tattnall and Gedney, who were detailed to make a survey of the Dry Tortugas, and beg leave to call your attention to the importance of this position to the United States, as a naval station. I also respectfully recommend that the appropriations necessary to make a scientific examination of its capacities for its defence may be granted.


Navy Department, March 25, 1830.

Sir: I have the honor to transmit herewith the report of Lieutenants Tattnall and Gedney, who were selected to make a survey of the Dry Tortugas, with a view to ascertain its fitness for a naval rendezvous and depot, for the use of the navy of the United States.

The result of their survey fully confirms the favorable anticipations formed from the general examination made by Commodore Rodgers, during the early part of the summer of 1829.

To the report itself, you are referred for many of the advantages which it combines and offers for such a station.

It is still, however, to be determined, whether this harbor is susceptible of such perfect defence as would justify its being selected as a site for the important purposes to which it has been proposed to be applied. As yet, no regular examination has been made by engineers, competent to decide the question of its defensibility. The officers who have made the survey, have expressed the opinion that a portion of it is entirely defensible. It is very important that this point be subjected to such investigation as will leave no doubt of the fact; and it is respectfully proposed that an appropriation be asked for, to enable the Executive to have the necessary scientific examination made, under the superintendence of the proper department.

It would be difficult to estimate the value of such a position for a naval rendezvous and depot, supposing it can be rendered entirely secure against the attacks of a superior maritime foe; perhaps no situation on all our southern coasts promises to afford the same important advantages.

It might be expected to give safe protection to the great and growing commercial interests of the States in the valley of the Mississippi, and contiguous thereto.

In time of war it would afford a place of security to the merchantmen of all the States to retire to, from the pursuit of an enemy, and at all times a place of refuge and relief to vessels in distress, and until they could be refitted for sea.

The cruising on the West India station would cease to have the terrors attached to it, which have heretofore been presented to the officers and seamen of the navy. Instead of encountering the pestilential atmosphere of the usual places of resort in those seas, after the usual short tours of service, they would find a healthy and refreshing retreat in the tranquil basins of these harbors, and the invalid might hope for a speedy restoration from the diseases incident to that climate.

Lying, as these islands do, directly in the track of vessels passing and repassing to so many points in the Gulf of Mexico, in doing which, they must be placed within the reach of the naval power of the United States, stationed at this rendezvous, it would give an influence which must be felt by all nations trading in those seas, and add to the inducements to preserve towards the United States the most amicable and peaceful relations.

The position of the Tortugas, from their proximity to the harbors from whence have issued the swarms of unprincipled depredators on the commerce of the United States, and which has resulted in such a loss of property and life, is peculiarly advantageous and commanding. Such are the facilities of egress from these harbors, that ships-of-war anchored there, could at any moment, and with any wind, immediately slip from their moorings, and sail in pursuit of vessels suspected of being engaged in unlawful enterprises.

The presumption is, that its occupation by the United States would completely suppress piracy from those ports in the Island of Cuba which have been heretofore so favorable for these purposes. I have the honor to be, very respectfully, sir, your obedient servant,


The President of the United States.

United States Sloop Florida , February 28, 1830. Sir: The duties assigned Lieutenant Gedney and myself, in your orders of the 24th of August last, having been completed, we have the honor to lay before you a correct survey of the keys and harbors of the Dry Tortugas, accompanied by the following remarks on the most important points to which our attention was directed by your instructions.

The harbors.

The large or outer harbor is in the centre of the whole group of keys and reefs. Its extent is a mile and three-quarters by a mile and a half, and its depth generally eight fathoms. The anchorage is clear


of rock, and the holding ground of the first quality. It has three entrances from sea, with water sufficient for the largest ships from the S. E., S. W., and north. The two former are safe and easy of access. That from the north is difficult, being much intersected by shoals, and should never be attempted by large ships but in cases of emergency. It would, however, be of great importance in time of war. We experienced, whilst at the Tortugas, several very heavy gales from various quarters, and never found sea enough in the harbor to render it an unsafe anchorage. Our own opinion is confirmed by that of the fishermen who have frequented it for many years. We have no hesitation, therefore, in recommending it as a safe and commodious man-of-war harbor. The small harbor consists of two basins, the longest of which is twelve hundred yards by seven hundred and seventy, and the smallest six hundred yards by four hundred. The depth of the former is from twenty-eight to forty feet, and of the latter from sixteen to twenty-four. The bottom is clear of rock, and the holding ground excellent. The entrances are from the outer harbor, by channels of thirty-five feet into the large, and twenty-three feet into the small basin. The two basins are connected by a channel of twenty-three feet, so that vessels may haul from one into the other without passing into the outer harbor. This harbor is so completely walled in by the keys and flats, that the water, in the heaviest gales, is perfectly smooth, vessels having nothing to contend with but the mere force of the wind. In the last hurricane which was experienced at the Tortugas, two fishing smacks were at anchor in the small basin, one of which rode out, the other drove on shore, and when the gale abated was got off without injury. This information was received from a fisherman who was on board the smack which rode out the gale, and who states that, although it was of almost unprecedented violence, there was not sea enough to cause the vessel to pitch. This harbor is in fact a natural dock; as easy of access, and as safe when in, as can be desired. It is small; but if vessels should moor, as is usual in docks, so as to occupy as little space as possible, it would accommodate the greater part of our navy.

The health of the keys.

We arrived at the Tortugas on the third of October, previous to which our men had been considerably exposed, and several were invalids. We were immediately occupied at work on the flats, standing in the water during the heat of the sun, and in cutting extensive paths through the keys. An officer and several men were in consequence attacked with the intermittent fever, but so slightly that they were readily cured, without the aid of a physician. On recovering they had not, in a single instance, the sallow appearance generally following southern bilious fevers, but almost immediately recovered their usual appearance and strength. A second exposure invariably brought on a relapse, but even then the disease was so mild as to be checked without difficulty. We have not, during the whole cruise, lost a man, nor is there a person sick on board the vessel. The family of the keeper of the light house, consisting of five, (all northern constitutions,) have enjoyed uninterrupted health, and we were assured by the fishermen that they had never known or heard that the keys were otherwise than healthy; and, to use their own words, "that they never consider it necessary, when there, to be particularly careful of their health."

There is, indeed, nothing to cause disease; no ponds, no deposit of sea muds, as at Key West. They are as healthy as the deck of a ship in the same latitude. The health of this year may be considered as a fair criterion by which to judge it generally, for the neighboring parts of the Florida reef have been more unhealthy than usual. At Key West the mortality has been so great that sixty-five of the inhabitants died out of one hundred and fifty, and of the whole population very few escaped sickness entirely.

Susceptibility of defence.

On this point we can merely venture an opinion, as our profession does not lead us to any accurate knowledge of the subject. As a mere matter of opinion, however, we would say that the outer harbor could not be so defended as to prevent the entrance of an enemy, although the forts for the protection of the basin would prevent its occupation. There can be no difficulty, we think, in fortifying the basins, so as to render them perfectly secure. Should the keys not furnish sufficient space, the flats would afford as much as could be required. They are dry in some places, and have generally from two to three feet water on them. They are well located for this purpose, do not shift, and appear to be suitable foundations for the heaviest works. We refer you, sir, to the journal of the survey accompanying the report, for our further views in relation to this subject.

The opinion that some have entertained, that the keys are overflown in heavy gales, is certainly erroneous. This did not occur in the hurricane alluded to. Their location is very different from that of Sullivan's Island, and other islands on our coast, which have been subjected to this inconvenience. They have no main land near them to back the water, which, meeting with no obstacles, flows freely through them. The highest of the keys which would be fortified is from three feet nine inches to four feet one inch above the level of the highest tides which we experienced in four months.

The facility of supplying the place in the event of war.

By a reference to the chart, it will be seen that the keys and reefs occupy a circumference of thirty miles; that the three channel ways from the sea for large ships, are all in opposite directions, and that there are numerous passages through the reefs by which vessels of a light draught of water might enter the harbor. To these advantages may be added the excellent navigation for small vessels throughout the whole Florida reef; that they could be protected by convoys to within seventy miles of the Tortugas, and the vicinity of the gulf stream to the latter, which would subject blockading vessels to be frequently drifted from their stations. It would appear, therefore, that, if the station could be effectually blockaded at all, it would require a much larger force than any power could devote to that single object.

The importance of the position.

We can furnish but little information on this subject, which the Department does not already possess. Its importance as the doubling point of our commerce, to and from the Gulf of Mexico, is shown by the fact that, in a little more than three months, one hundred and thirty-one vessels, principally square rigged, passed in sight during the day, and it is presumable that an equal number may have passed at night. In


this number, the smacks and other vessels frequenting the Tortugas are not included; we would, however, suggest one point of view, in which its occupation may prove of great importance. The vicinity of St. Domingo to Cuba, and the nature of the population of the two islands, render it by no means improbable that, at a future day, their political condition may be the same. In this event, the proximity of Cuba to Florida, which must always be the weakest portion of the southern country, may be attended with imminent danger, particularly should we be engaged in a war with a naval power disposed to encourage a descent on the coast. A fortress at the Tortugas, looking directly into the port of Havana, in conjunction with a naval force, would be a strong, if not an effectual check on such a disposition, and give us, at all times, the control of the island. The principal disadvantage under which the position would labor, is the want of fuel; that of water could be remedied by tanks, and, in this respect, it would be in no worse condition than Gibraltar and some other important fortresses. The flats would afford, for this purpose, as much surface as could be required. Fuel might be supplied from the continent or neighboring keys on the reef. The want of fuel, however, does not appear to be a sufficient ground for not occupying the position, for if it can be supplied at all, it can as easily be supplied with one article as another. Owing to the mildness of the climate, the expenditure of fuel would be less than on the continent; it would be required only for cooking.

On all minor points, sir, connected with the subject, we beg leave to refer you to the journal. I am, sir, with great respect and consideration, your obedient servant, (Signed) JOSIAH TATTNALL.

The Hon. John Branch, Secretary of the Navy.