4 
662 Dr. ingenhousz’s Improvements 
or cylinder. I alfo thought another material advantage 
might be derived from a plate of glafs, as the form of it 
admits of placing culhions or rubbers upon different 
parts of it, and taking the electricity, excited by thefe 
rubbers, from the interfaces between them, which can- 
not conveniently be done when a globe or cylinder is 
xifecl. The only inconvenience which I at firft conceived 
would enfue from it was, that the center upon which the 
plate was to be fixed and whirled round, would always 
be too near the rubbers (unlefs thefe were very fhort, or 
the plate of a confiderable fize) and that thefe would 
throw the electricity, collected on the furface of the 
glafs, upon that very center. In order to obviate this 
difficulty, I propofed to make the center likewife of glafs, 
or fome other non-conduCting fubftance, as, for inftance, 
baked wood. 
I began firft: by making ufe of one of thofe glafs ftands, 
which they call a waiter, and which has a glafs fupport 
fixed at right angles to its center. I whirled the waiter 
round as well as I could, rubbing it fometimes on one 
fide, fometimes on both. In this imperfeCt ftate I ffiewed 
it to Dr. franklin, who approved much of the fcheme, 
•and advifed me to purfue it. Soon after, I ffiewed it to fe— 
veral of my acquaintance, and in a fhort time I found 
fuch machines ready made at Mr. ramsden’s and fome 
2 other. 
