A TREATISE 



looke at die paper through 'his priffne fituatcd in fuch fcrc as we 

 haveabovedetermined,andhe will perceive a whitim or light- 

 fome {hadovv proceed from the lively picture that he feeth of 

 white, and moote out neerer towards him then that lively 

 picture is, and he will difcerne that it commeth into the glaflc 

 through a part of it neerer to his eye or face, and further from 

 the object then the ttrong image of the white doth. And fur. 

 ther^if he cauCeth the neerer part of the paper to be covered with 

 ibine thin body of a ladder colour , this dim white vamfheth : 

 which it doth not if the further part of the paper be covered. 

 Whereby it is evident, that it is a fecondary image. proceeding 

 from the hit her part of t/ie paper. 

 4* Nowti.tn > nriakculeofwhat we havcfaidro the finding out 



J of the reafon why the red and blew and other colours app^are 

 ot the various , , , J t . , , 



colours that when one lookerh tf rom, < a orilme : let us proceed upon our 



appeare in former example, in w ! ic. j a w ire paper lyeth upon a black car- 

 looking pet(ibr,the diamerrall oppotition o 'tuoiL co.ours maJceth them 

 through a mo ^ remarkable) ii. fuch iort tt at there be a rarcell of black rn 

 jprifmc. , the hither fide of the paper : and rhtreln, let us examine accord* 

 ing to our grounds , what colours muit appcare at both tnds 

 of the paper looking upon them through the triangular 

 glafle. 



To begin with the furthelt end , where the black lyeth be- 

 yond the white : we may confider , how there mutt come from 

 the black, a fecondary darke miflyfhadow (be/ides the tfrong 

 black that appeareth beyond the paper ) wliich muft /hoore to- 

 wards you(in fuch (brt as we (aid of the whinth light fome ilia- 

 dovy) andconfequently, rnu(Uyover the hrong picture of the 

 white paper : now in this cafe, a third middling colour mutt re- 

 fult out of the mixture of thefe two extremes of black and white; 

 fince they come to the eye, almoft in the fame line, at the leaft 

 in lines that make fo little a difference in their anglesas it is net 

 difcernable. 



The like whereof happeneth in Clothes, or Stuft,or Stock- 

 ings, that arc woven of divers coloured but very fmall thredsi 

 for you ftand fo far olffrom /uch a piece of S ruffe, that the little 

 threds of different colours which lye immediate to one ano* 

 ther may ccme together as in one line to your eye ; it will 

 appearcofa middling colour, duferent from both thole that it 



refulrcth 



