VOL. II.] PHILOSOPHICAL TRANSACTIONS. 217 



What the cause may be of that fungous excrescence, or why liorses are ne - 

 culiarly obnoxious to it, or what kind of horses most, I have not considered. 

 But I cannot think it comes from straining in great draughts, in races, or from 

 hard travelling, because I have seen very large spunges (as I may call them) in 

 young horses' eyes of two and four years old before they were backed ; which 

 after they have been taken up from grass and kept witli dry meat, have very 

 much abated, and afterwards being turned again to grass in the spring, have in- 

 creased again to the wonted largeness. But whether it were from their moist 

 feeding, or holding down their heads to eat (whereby there might be a greater 

 deflux of humours to that part) I cannot determine. But as there are few 

 horses quite free from this evil, and many rendered very inconsiderable by it, I 

 will recount the most remarkable cases which make horses most useless and 

 suspected : 



1 . The more and greater those excrescences are, the more the pupil of the 

 eye or sight is in danger of being quite obstructed ; which you may farther ex- 

 amine by turning the horses' eye to the light, and observing how much of the 

 pupil they obstruct. 



2. Spunges on the upper edge of the uvea are apt to grow the largest, and 

 hinder the sight most. 



3. That which grows on the middle of the uvea hinders the sight more by 

 distracting the object, than that which grows in either comer or angle of it. 



As for the cure, I suppose there can be none expected, but from a drj ing 

 kind of diet ; though perhaps outwardly something may be devised to shadow 

 the eyes, and keep them from being nakedly exposed to the sun, whereby the 

 pupil will not be so closely contracted, and consequently the sight not so much 

 obstructed. 



Of Spots seen in Venus. By S. Cassixi. N° 52, p. 613. 



S. Cassini discovered, October 14, l666, at 5 h. 45 m. p. m. near the cen- 

 tre of Venus, on the north side, a part brighter than the rest ; and at the same 

 time westward two obscure spots, somewhat oblong. Which parts he could not 

 well perceive again till April 28, 1667 ; on which day, a quarter of an hour be- 

 fore sun rising, he saw again a bright part, situated near the section, and dis- 

 tant from the southern horn a little more than 4^ of its diameter ; also near the 

 eastern ring he saw a dark and somewhat oblong spot, which was nearer to the 

 northern than the southern horn. At sun rising he perceived that this bright 

 part was then not so near the southern horn, but distant from it J- of its diame- 

 ter, which gave him great satisfaction. But he was surprised at the same time 



VOL. I. E E 



