X la I'be Art of Farriery 



verged in Opticks. I fhall now proceed to a Defcrip- 

 tion of the third Humour. 

 The jd The third is called the Vitreous or GlafTy Hu- 



Humeiir. ^^^^ j^ j^j^gg ^p ^j^^ greatefl Part of the Eye, 

 filling all the hind Parr of the Globe. It is Sphe- 

 rical behind and in its Middle ; before, it is concave 

 or hollow, and in the Cavity the Cryftalline Hu- 

 mour lies. 

 The Vitre- The Vitreous is a very tranfparent Subflance, not 

 ous Hu- fo hard as the Cryftalline, or fo fluid as the Aque- 

 itibed^" ous or Watery Humour ; and it feems to be nothing 

 elfe but a Number of delicate little Veficles or 

 Bladders full of Water ; for in touching, it is al- 

 ways molll: and waterifli, and when cut, the Mix- 

 ture flows out more abundantly j or by rubbing it 

 betwixt the Palms of one's Hands, the Water comes 

 out, and to fuch a Degree, that it will appear 

 nothing but a Membrane or thin Skin ; and by ob- 

 ferving with a Microfcope or Glafs commonly called 

 a Magnifying-Glafs, when it is cut, you will ob- 

 ferve many little Airy Bubbles to arife from it, but 

 being dried, it evaporates or flies away, and this de- 

 licate membranous Body feems almoft withered to 

 nothing. 

 The Ufe of The Ufe of the Vitreous or Glafl*y Humour, feems 

 ^^x H^l^^' ^^^^i^fly defigned to keep the Cryftalline at a proper 

 DTJOVir. Dillance from the Retina, as I fliall farther ex- 



plain in fpeaking of Vifion : For I hope the Rea- 

 der will pardon my Prolixity, with relation to a 

 Pifcourfe of that fo admirably contrived Organ the 

 Eye, feeing fo many People are cheated with Horfes 

 that have bad ones, nay fometimes with fuch as are 

 ftone Blind. Therefore, 1 fay, if the Reader will 

 only lludy over this Chapter a little, he may moft 

 certainly judge of the Soundnefs of a Horfe*s Eyes ; 

 and thereby Ihun the Lofs which accrues upon buy- 

 ing a Blind Horfe, as well as the Cenfure of ixie 

 Neighbours, for his Ignorance in that Particularo 

 Now to return,. 



The 



