Chap. 4. P H J L OS O P H Y. . 377

tion a ; and therefore not inconfiftent with what has been faidabove, that, the planets move in fpaces free from refiftance b .

; . .i . , ‘ l:'' '

19. In order for the more full difeovery of this adtion between

light and bodies, our author began another fet of experi-ments, wherein he found the light to be adfed on as it paffesnear the edges of folkf bodies ; in particular all fmall bo-dies, fuch as the hairs of a mams head or the like, .held in avery fmall beam of the, fun’s light, A call extremely broad fha-dows. And in one of tfyefe experiments the fhadow wa s5 y times, the breadth,of the; body c . Thefe lhadows are alfoobferved to be bordered with colours d . This our author callsthe inflexion of light; but as he informs us, that he was interrupt-ed from profecuting thefe experiments to any length, I neednot detaip my readers with a mpre particular account of .them.

- ' V -••d.'.- ^ Cm A p. IV. ' - ! .<n.-

;;;; ; .pf optic glasses.

O IR Isaac Newton having deduced from his dodtrine^ of light and colours a furpriling improvement of ,tele-fcopes, of which I intend here to give an account, I fhallfir ft premife fomething in general concerning thofe inftru-

ments. r ' . ..: r u

. ^ *. , - 1 { • ■ .* • > * • »

“> l ‘g See Coocl. S, 1 ; I ' « Opt. B. III. Obf. 1 .

» B. II. Ch. 1 . 1 t Ibid. Obf. 2 .

■A

. >: ’... - iC c c 2. It