London, 18th. July, 1804.
Being confidently persuaded that you will not treat with indifference any thing which tends to the improvement of that branch of science on which depends the safety of Mariners and the facilities of Navigation, I have taken the liberty, although a stranger, and on the Eastern side of the Atlantic, of transmitting to you a few copies of the inclosed little pamphlet, descriptive of some material alterations in the construction of the nautical Sextant and of the Mariners Compass.
By means of the new alterations of, or rather additions to, the Sextant, it is presumed that this valuable Instrument will be found more particularly adapted than heretofore to the purposes both of Land and of Maritime Surveying, as well as to the practice of making celestial observations at Sea, in which it particularly facilitates, in a great degree, the true determination of the longitude; and it will, I presume, be found especially useful in such ships as may happen to have but one or two persons on board capable of making the requisite observations.—You will perceive, also, that the pamphlet contains an Explanation of several improvements in the construction of the Azimath Compass, which render that Instrument considerably more accurate than any other heretofore constructed, and of which, it is trusted, that your Excellency will approve.
I trust, Sir, that you will excuse the liberty which I have taken in transmitting these pamphlets to you.—But, from the local circumstances of the extensive Country over which you so happily preside,—from its increasing commerce and prosperity under your auspices,—I cannot but suppose that these Instruments would be equally acceptable in the United States as in Europe. I beg leave to state that they have already been honoured with the approbation of the Naval Boards here, and of the Corporation of Trinity House, together with the flattering testimony in their favour of some of our most distinguished Naval Characters, as Sir Sidney Smith, Sir Home Popham, Mendoza de Rios Esqr. F.R.S. of the Royal Navy of Spain, and many other gentlemen particularly eminent for their nautical and Scientific knowledge; and should I, Sir, in addition to these, have the high honour of the approbation and sanction of your Excellency, I shall deem myself amply compensated for the attention and expense which has been bestowed on the subject.
With the highest respect, I have the honour to be, Sir, Your Excellency’s most obedt. Servt.
DLC: Papers of Thomas Jefferson.