602 PHILOSOPHICAL TRANSACTIONS. [aNNO 1701,, 



stance, that when some of the former water was gently evaporated, many salt 

 crystals remained behind ; but the well-boiled-water, so evaporated, left no 

 crystals. As to the razors, he found none, but when viewed with the micro- 

 scope, showed nianv notches on the edges ; an appearance common enough. 



Part of a Letter from Mr. Antony Van Leiiivenhoech, F. R. S. concerning 

 several Microscopical Observations. Delft in Holland, June 21, 1701. 

 N° 273, p. 903. 



About 3 years ago I was shewn a magnifying glass, whose chief excellence 

 was, that one could see an object a great distance from it. As soon as I had 

 put the glass to my eye, I concluded there was a hole or cavity in it, by which 

 the remote object came to be seen ; and viewing it by one of my own, I not 

 only discovered one deep pit or cavity in it, but several other lesser, which had 

 not been ground out. Last winter a glass-grinder came to me with a magni- 

 fying glass, by which he said he could see into metals and minerals. I answered 

 that the pores of metals were so close and impervious, that it was impossible 

 ever to see through them ; and that leaf gold, though ever so thinly beaten, 

 could not be seen through. 



Upon which he put the glass into my hands, adding, that I should see the 

 light of the candle through a copper circle, which stood before the magnifying- 

 glass, and accordingly I saw a very imperfect light through the copper circle. 

 But this was only occasioned by a small part of the glass, which was not ground, 

 as I discovered by applying an extraordinary magnifying-glass. 



It has often happened that in the bursting of glass, or of sparks flying out of 

 wood-coals, small particles of the glass or fire came into my eye, and caused it 

 to smart ; upon which I used to arm my eyes with spectacles, against the like 

 accidents for the future. Now I observe, when I look through one of my 

 glasses by candle light, that near the upper part of my eye in the tunica cornea, 

 there appears a fine small flame of a candle inversed, no larger than the com- 

 mon letters we use in writing, and opposite to it appear two round clear lights, 

 so very small, that the flame of the candle is not to be perceived in it. From 

 hence I conclude, that the tunica cornea of the eye, by the wound it received 

 from those particles of glass, has lost somewhat of its roundness, which occa- 

 sioned those appearances, and that when the wounded part stood just before 

 the sight, it obstructed it, &c. I observed also, that in several places of the 

 tunica cornea, there lay veins no longer than the breadth of 2 or 3 hairs 

 put together, wherein I could perceive the globules of blood very distinctly ; 

 these vessels were so small, that they could contain but one globule in their 

 diameter, and the blood had no motion. The vessels seem to be broken off 



