A discourse on the invention and improvements of the reflecting telescope. Delivered at the anniversary meeting of the Royal Society, November 30, 1777. / By Sir John Pringle, Baronet, President. Published at their request.

  • John Pringle
Date:
MDCCLXXVIII [1778]
Catalogue details

Licence: Public Domain Mark

Credit: A discourse on the invention and improvements of the reflecting telescope. Delivered at the anniversary meeting of the Royal Society, November 30, 1777. / By Sir John Pringle, Baronet, President. Published at their request. Source: Wellcome Collection.

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    cal figure of lenfes. This circumffance forced, as it were, Newton to fall into Gregory’s track, and to turn his thoughts to reflectors, flbe different ref Tangibility of the rays of light (fays he, in a letter to Mr. Oldenburg, fecretary to this Society, dated in February, 1672) made me take reflections into confederation, and finding them re¬ gular, fo that the angle of reflection of allforts of rays was equal to the angle of incidence, I underflood, that by their mediation optic inflruments might be brought to any degree of perfection imaginable, provided a reflecting fubflance could be found which would poliflo as flnely as glafs, and re¬ flect as much light as glafs tranfmits, and the art of com¬ municating to it a parabolic figure be alfo obtained. . . . Amidfl thefe thoughts I was forced from Cambridge by the •5 '' intervening plague, and it was more than two years before I proceeded furtherff>. It appears then, that if Newton was not the firft in¬ ventor of the reflecting telefcope, he was the main and effectual inventor. By the force of his admirable genius he fell upon this new property of light, and thereby found that all lenfes, of whatever figure, would be af¬ fected more or lefs with fuch prifmatic aberrations of the rays as would be an infuperable obftacle to the perfection (f) Phil. Tranf. n. 80. B of 4