London, The Royal Society, 1771. Small 4to (23.1 x 17.5 cm). 24 pp. [numbered 417-440]; two text illustrations. Spine covered with marbled paper.

Interesting paper, based upon some questions raised by Benjamin Franklin, read before the Society on 20 December, 1770, by the Reverend Samuel Horsley (1733-1806), mathematician and – later – Bishop of Rochester (1793), and member of the Royal Society, which he left after quarrels with the famous chemist Joseph Priestley (on religious matters) and Sir Joseph Banks. These are among the earliest - if not the earliest - doubts expressed about Newton's corpuscular theory. Disbound from the Society's Philosophical Transactions. Wide-margined. A very good, clean copy.