OF GLASSES FOR OPTICAL PURPOSES 35 



But onely the quality of the eye ys to see, and 

 begynneth at a poynte, withoute any quantity or 

 bignes. As for example you may knowe yt by 

 this : Pricke a hoale in any thinge, with the poynte 

 of a fine needle, and then holde that vnto your 

 Eye, and beholde any thinge thorowe the hole, 

 and you may see a greater thinge, if that yt bee 

 any distance from yow : yow may beholde a 

 whole towne, beeynge a greate distance from 

 you, &c. And for that perspective ys the dis- 

 cerning of any thinge either substancyall or acci- 

 dentall, accordinge to the bignes, and distance, and 

 hath his boundes, betweene too righte lynes, from 

 a poynte : And so extending infinitely from the 

 sight of the Eye, yt showeth yt self according to 

 the quantity or bignes, correspondent vnto the 

 distance. And for that perspective ys muche 

 amplifyed and furdered by the vertue and meanes 

 of Glasses, I do thinke yt good to shewe the pro- 

 perty of glasses : And suche, as touchinge the 

 nature and quality of glasses, commonly called 

 Lookinge Glasses. Whiche are those sortes of 

 Glasses, that have a ffoyle, layde on the backe syde 

 thereof, that causeth the same glasse to cast from 

 yt a beame or shadowe, accordinge vnto the 

 forme of that thinge that standeth ageanst yt 

 shewynge yt vnto the sighte of the eye. Whereof 

 there ys three severall sortes, accordinge vnto 

 the sundry makinge and polisshinge of these 

 glasses : I do not meane sondry sortes of stuffe, 

 ffor that theare ys some sortes of lookinge glasses 



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