

( 61 ) 



with a proportionable quantity of the gkttinous or gummy matter 

 before-mentioned. In fliort, there is no doubt that the fame perfec- 

 tions exifl in a newly-hatched Silk-worm, as can be difcovered in one 

 full grown. 



I have frequently examined the flying infecfl, moth or butterfly 

 produced from the aurelia or chryfalis of the Silk-worm ; and, hav- 

 ing before particularly defcribed the eyes of this creature while a 

 worm, 1 now employed myfelf to difcover the nataire of its eyes, 

 when changed into a moth ; and for this purpofe I placed before the 

 microfcope one of thofe organs of fight, which in this animal is com- 

 monly deemed one eye. This is protuberant or rifing above the 

 head, rather more than an hemifphere, and is compofed of a number 

 of fmaller optical organs : Thefe I counted with the greateft exa6l- 

 nefs I was able, beginning at the bottom of the hemifphere, and pro- 

 ceeding to the fummit or uppermoft part of it, which diftance made 

 the fourth part of a fpliere ; and in this fpace I counted thirty-fix op- 

 tical organs or eyes. But, not fatisfied with my own computation, 

 I delivered the microfcope to the limner, defiring him to count them, 

 and in the fame fpace he reckoned thirty-five. This latter number I 

 will fuppofe to be right, and from it I proceed to compute as follows : 

 — If tlie fourth part of the circumference or great circle furroundinga 

 fphere contains thirty-five, the entire circumference will contain 140. 

 Now Metius informs us, that having the length of the great circle in 

 a fphere, the calculation of the whole fuperficies of fuch fphere is befi: 

 andeafiefi: computed, thus: As 22 is to 7, fo is the quadrature of the 

 great circle to the fuperfices of the fphere, therefore in the prefent 

 cafe the computation is as follows ; — 



As 22 7 19600 140 the circumference or length of the great 



7 140 [circle. 



I m . I 



22)137,200(6236 5600 



• 140 



19600 the quadrature of the great circle. . 



