French Catalan mathematician, physicist, astronomer, and politician (1786-1853). Handwritten manuscript in French, unsigned, four pages on two adjoining sheets, 7 x 9.5, no date. Arago writes on the topic of "Refraction terrestre [Earth refraction]." In part (translated): "In the computation of geodesic observations, it is supposed that the curve, concave towards the earth, which a ray of light traverses from one station to another, is a great arc of a circle. It is easy to see that in this hypothesis the effect of terrestrial refraction must be proportional to the angle formed between them by the vertical of the two stations, or, what is the same thing, to the extent of the arc of the great circle which joins them. The observation then has only to determine, that the fractional number by which this arc must be multiplied and that it is agreed to call the coefficient of refraction…The important role played by this coefficient in all Trigonometric leveling imposes on me the duty to record here units of value which M. Coraboeuf assigns." In very good condition, with areas of ink erosion and writing heavily showing through from opposing sides.
This item is Pre-Certified by PSA/DNA
Buy a third-party letter of authenticity for
$75.00
*This item has been pre-certified by a trusted third-party authentication service, and by placing a bid on this item, you agree to accept the opinion of this authentication service. If you wish to have an opinion rendered by a different authenticator of your choosing, you must do so prior to your placing of any bid. RR Auction is not responsible for differing opinions submitted 30 days after the date of the sale.
We use cookies on this site to improve your experience. By using this site, you accept our use of cookies. To learn more, please see our Privacy Policy.
