( f40 ) 
Drops of Fair Wafer being let fall on a piece of Plain 
Glafi, form ihemfelves into PUfic Convexes^ having a 
Convexity proportionable to the heights, from which 
they <iefcend, from a greater height, a lefs, from a left, 
a greater degree of Convexity. I applied feme of thefe 
as Reading GlafTes, for fingle Words of fmall Letters, as 
on the Globes and Maps, and found no other Incon- 
veniency, then that the Fluidity of the Water obliges 
one to keep the Glafs Horizontal, which I after deviled 
a way to Remedy. 
I took a fufEcient quantity oflzing-Glafs and diffolved 
it in Water over the Fire, and whilft 'twas warm I dipt 
a ftick into the Solution, and let fome Drops of it fall 
on the Glafs as before, and in a Quarter of an Hour 
they acquire a Confiftency, that permits them to be 
held in any Pofition, and tho' they are not altogether 
fb tranfparent, yet this is little or no impediment to 
their ufe. The drops of this Solution are more exadly 
defined then thofe of Common Water, having their 
edges exadly Circular, and one may make them of a 
much longer Focus then thofe. I applied fome of thele 
lenres to a hole in a darkned Room, and found they 
rendred the Images of Objefts with but an indifferent 
diftindnefs. 
A thin flat Ring of Brafs, hot exceeding 4 Tenths 
of an Inch Diameter in its interior Circle being cemen- 
ted to a plain Piece of Glafs, and filled with Water or 
the Solution now mentioned, then by preffing the Fin- 
ger into it, till what isfuperfluous be taken off; there 
will be formed a piano Concave which may ferve as an 
Eye Glafs to a Profpedive, or to any other optical 
ufe Concave GlafiTes are applicable. 
I have tried what would be the fuccefs of Combining 
Portions of Water by the help of Brafs Rings, and plain 
pieces of Glafs, to give them their true Figure and 
requifite 
