OF GLASSES FOR OPTICAL PURPOSES 43 



concave or hollowe inwardes and well polysshed 

 as I will hereafter furder declare. 



CHAPTER VII. 



The seconde quality of this glass made in the 

 forme before declared. 



The quality of this Glass ys, if that the sunne 

 beames do pearce throughe yt, at a certayne 

 quantity of distance, and that yt will burne any 

 thinge, that ys apte for to take fyer : And this 

 burnynge beame, ys somewhat furder from the 

 glasse, then the perspective beame. 



CHAPTER VIII. 



The tkyrde quality of this kynde of Glass, that ys 

 grounde, and made in that forme before declared, 

 ys to reverse, and turne that thyng that yow do 

 beholde, thorowe ye glass, to stande the contrary 

 way. 



And yf that yow doo beholde any thinge 

 thorowe this Glasse, and sett the glasse furder 

 from yowe then the burninge beame, and so 

 extendinge after that what distance that yow list, 

 all suche thinges, that yow doo see or beholde, 

 thoroughe the glasse, the toppes ys turned 

 downwardes. Whether that yt bee trees, hilles, 

 shippes on the water, or any other thinge what- 



