OF BODIES, Chap-XXXi. 325 



they arc to be perpendiculars unto that fupcrficie:, fo much the 

 thicker they are : it fblloweth, that this dilatation of light at its 

 comming out of the glaffe, imirt be made and muft encreafc 

 from that fide where the angle was leaf i at the going in, and 

 jreatcftat the comming out : fothat,theneerer to the contrary 

 fide you take a part of light, the thinner the light muft be there: 

 and contrari\vile,the thicker it irmffbe, the ncercr it is unto the 

 fide where the angle at the rayes comming out is the greater. 

 WhercfbrCjthc ftroageft light, (that is,the place where the light 

 is leaf I mixed with darknefTe)mufi: be neercr that fide then the o- 

 ther. Confequently hereunto,if by an opacous body you make a 

 iliadow comprehended within this light, that fliadow muft alib 

 have its ftrongefl part , neerer unto one of the lights betwixt 

 which it is comprifed, then unto the other : for , fliadow being 

 nothing elfe , but the want of light , hindred by fbme opacous 

 body; it muft of nccefTity lie averfed from the illuminant , jutt 

 as the light would have laine if it had not been hindred. Where- 

 fore, feeing that the Stronger fideof light , doth more impeach 

 the darknefle,thca the feebler fide dotfi ; the deepeft darke muft 

 incline to that fide, where the light is weake/t j that is,towards 

 that fide on which the fhadow appeareth , in refpe& of the opa- 

 cous body or of the illuminant , and fo be a caufe of deepnefTe 

 of colour on that fideof it happen to be fringed with colour . 



THE ONE AND THIRTIETH CHAPTER. 



T'kt C4nftJ if cert Mine nfpetntncti in lttm*9Vtt ctUurs ; with 4 

 concltt^ntflkt Mfcsttrfe touching the fertfes tndtht 



I 



Ut of thele grounds we are to fecke the reiblution of ail The rcafon of 

 luchfymptoms as appear unto us in this kind ofcoloun. cach feverall 

 Firrt therefore calling to mind, how VYC have already SSSJfol 

 declared, that the red colour is made by a greater proportion of ^ y \ { ^ pa ffi n g 

 light mingtedv^ithdarkneffe, and the blew with a leflc proper- through a 

 tion : it mult follow, that when light pafleth through a glaic in prifmc. 

 fuchfbrtas to make colours 5 the mixture of tiac light and -dark- 

 cflc on that fide where the light is ftrongeft will cnciinc to a 



red: 



