James Madison Papers

To James Madison from David McClure, 7 March 1815

Philada. March 7th. 1815


I have long Since been under the impression that a Navy school would be of importancce to the United States. I am happy that at length one or more have been recommended, and now the subject is under consideration. I presume it is well known to you that I have been the Principal of a Nautical Institution in this city for some time, and that a large proportion of Navy Officers have been under my instructions. This would in a measure apologize for my presumption in offering myself a Candidate to serve the United States as Professor of one of their Navy Schools.

It is with a degree of independence though not altogether without modesty that I address you on this subject, for I have to state that my present encouragement both in the Mathematical and Nautical department is such as amply rewards me for my labours. My desire is to have my talents employed in a manner to produce that most general benefit, and it would be a point of ambition to serve the country that gave me birth.

As the boundary line between the United State & Great Britain is required (according to the late Treaty) to be accurately laid down, I deem it of consequence to communicate to you an important improvement which I have lately made to an Artificial Horizon, invented some years ago for the use of my students.

This Artificial Horizon consists of four Strips of well seasoned Mahogany or Walnut about ten feet in length and six or eight inches in breadth; one edge of each to be made perfectly straight.

Those Strips make the Artf. Hor. and when in use form a square each corner of which is supported by a Stand made for the purpose

To Adjust this Artif. Hor. there is in each Strip a gutter nearly filled with quicksilver and covered with glass so that it would be attended with no difficulty in ascertaining (by the bulb in the quicksilver and by mean of a screw in each Stand) where each ship is in the horizon. You will readily perceive that the Adjustment will correct itself; for in passing round the Ships in Succession if the end of the last coincides with the end of the first, the adjustment will be correct and each Strip in the Horizons.

The Merits of this Artificial Horizon I have abundantly proven by innumerable astronomical observations and particularly when ascertaining the Latitude & Longitude. I have in a very imperfect manner described this invention and have deemed the bulk of a letter insufficient to prove its superiority to all others now in use. I have conversed with a gentleman of eminent talents who was educated in Europe and is acquainted with the various improvements made there, and he states that he has not seen any Artif Hor. that satisfies his mind as well as the one described to you

Should you feel inclined to attend to this Artif Hor. I shall esteem it a pleasure to send you a model, with the instruction how it is to be used, and some evidence of its superiority

I should be happy to receive an answer on both subjects of this letter. I am your most obedient Servant

David McClure
Principal of
the Naul. & Mathl. Academy Phila⟨   ⟩

DLC: Papers of James Madison.

Index Entries