Of Light and Colours.

Since a Lens does in the manner ,of 3Prism, more or less separate the Rays of

Ligh £

of Matter, and consequently in Bulk; and since th®Quantity of Motion is in the Ratio of the Bulk an®Velocity, (in this Cafe) ’tis plain, the greater the V®'locity is, the less will be the Bulk; and therefore thol®Rays of Light which suffer the greatest Refractionless in Bulk or Magnitude than others which are not >®much refracted, the greater Particles being not so mutysubject to the Povyer of the Glass ; as a large Needle )Snot so easily moved by a Loadstone, nor at so great aDistance.

3. This being the Cafe, ’tis easy to be understood’

that when a Beam of Light, as PI F, is let into a dayRoom, through a Hole in the Window-Shutter, and **made to fall on a Prism A C B at F, it will be attract®by the Surface of the Glass at F in a perpendicularrection, and cause the several Particles to deviate fr° .their right-lined Course to T, (which they before ha 'and decline towards the Perpendicular a b, that is,wards the Parts F a within the Glass ; which Deviat* 0 ^or Refraction will be greater in Proportion as the P astides of Light are smaller. j

4. Hence the several Particles of Light will P r0 ^ e£ ^from the Side A C to the Side D C in different D* r f^tions j where, when they arrive, and go out again 1to the Air, they will be again affected by the fame ®tracting Power of the Glass, which will here pro® ^the fame Effect as before, that is, it will cause e ®Sort of Ray to incline towards the Side of the G 1 ® ’and consequently to be refracted from the Directions tseverally had in the Glass, and from the Perpendis®

IT. est}

5. Thus those Rays, whose Particles arewill deviate least from the Perpendicular, and wiH ^fore go to R, and make the lowest Part of the c0 °rj'j 1 sSpectrum, and these will appear pf a Red Colour- o( cParticles next less in Magnitude will be somewhat tn^refracted, and will go to O, and be of an Oru»i e