670 Dr. ingenhousz’s Improvements 
I faw, two years ago, at the Duke of chaulnes at 
Paris, an apparatus which had a plate glafs five feet dia- 
meter. This alone coft him eight hundred French 
livres. 
As I had not adapted the tin condudlor to receive the 
electricity from the three disks, but only from the front 
disk, I cannot tell whether the force of eleClricity would 
have been proportionably ftronger if I had made fome 
metallic communication between each of the disks. 
I found, that the apparatus, as it was conftructed, could 
not eafily have admitted more than three fuch large 
disks ; for the twelve furfaces expofed to friCtion being 
each a foot and an half long,, and above three inches 
broad, made fo much refiftance to the working of the 
machine, that it required a ftrong arm to work it. 
Being fatisfied with having found that by this, or a 
contrivance of the fame kind, a much greater power 
could be excited than by the common glafs apparatufes; 
I did not chufe to put myfelf to more trouble or expence 
to increafe the ftrength of its frame, or the number of 
disks. 
I muft obferve, that fuch a machine may be kept in 
good order in a heated room ; but that it will foon lofe 
its force in countries where it is not the cuftom to heat 
rooms as the Germans do. My pafte-board disks kept 
2 very 
