OF BODIES.Chap.XXX. 323 



To begin then., wee may obferve,that light patting through 

 2 pjifme, and being caft upon a reflecting objects not alwayes 

 colour ; but in fbme circumtfances it Itill continued! light, 

 and in others it becommetk colour. Withall wee may ob/crvc 

 that thofe beames which continue light, and endure very little 

 mutation by their paflage , making as many refractions, do 

 make much greater deflexions from the ftraight lines by which 

 they came into the glafle, then thofe rayes doe which turne to 

 colour ; as you may experience, it you oppofe one fiurface of 

 thegJaffe perpendicularly to a Candle, and let a paper (not ir- 

 radiated by the candle; cppofite to one of the other fides of the 

 glafle : for upon the paper , you fliall fee faire light fnine with- 

 out any colour : and you may perceive., that the line by which 

 the light commeth to the paper, is almoft perpendicular to that 

 line by which the light commeth to the Prifme.^But when li^ht 

 becommetli colour , it ftriketh very obliquely upon one fide 

 of the glafle ; and commeth likewife, very obliquely out of the 

 other, that fendeth it in colour upoh a refle&ent body > fb that 

 in conclusion, there is nothing left us whereupon to ground the 

 generation of fuch colours , befides the litdenefle of the angle 

 and thefloapingnefleof the line, by which theilluminant Itriketh 

 one fide of the glafle and commeth out at the other, when co- 

 lours proceed from fuch a percullion. 



To this then we muil wholly apply our felves : and knowing 

 that generally , when light falleth upon a body with fo great a 

 floaping or inclination, fo much of it as getteth through , muf i: 

 needs be wcake and much diffufed ; it folio weth that the reafbn 

 of fuch colours , muft neceflarily confift inthisdflFufion and 

 weakene/Te of light ; whichthemoreitisdiffuied, the weaker 

 itroweth;and the more lines of darkncffe are between thelines 

 onight^and do mingle themlelves with them. 



To confirme this, you may obierve, how juft at the egrefle 

 from the prifme of that light which going on a little further be- 

 commeth colours, no colour at all appeareth upon a paper op- 

 pofed clole to the fide of the glaflejuntill removing it further off, 

 the colours begin to fliew themfelves upon the edges : thereby 

 convincing manifeftly, that it was the excefTe of light which 

 hindered them from appearing at the firft . And in like manner, 

 if you put a burning glafle betwcene the light and thcprifme, 



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