664 Dr. iNGENHouszfs Improvements 
center paffed through the middle of it. This ring was 
ftuck to the plates with fealing wax or fome other non- 
conducting cement; and the fpace between the center and 
the ring was carefully filled with the fame non-conduCt- 
ing fubftance. The conductor had two branches, each 
of which was placed between the two glaffes, reaching 
very near to the glafs ring. By this method all, or almoft 
all, the electricity excited by the eight cufhions, w'as 
forced to pafs upon the conductor, there being no way to 
reach the brafs center, between which and the conductor 
all communication was cut off by the above mentioned 
glafs ring being filled up with a non-conduCting cement. 
The power of fuch a machine, notwithftanding that the 
plates were not above fifteen inches diameter, was very 
aftonifhing. I faw one made in London with this im- 
provement (the glafs plates being eighteen inches dia- 
meter) by which a coated jar of two quarts w r as fully 
charged in lefs than five feconds. 
Mr., c. cuypers, an ingenious electrician at Delft, has 
not a little contributed to the improvement of thefe ma- 
chines, by making them lefs liable to be affeCted by damp 
weather. This gentleman, confidering that all glafies 
are not equally fit for electricity, and that j.*h. wartz, 
and after him Profeffor musschenbroek, were of opi- 
nion, that glafs, in the competition of which there enters 
7 a great 
