104 Hare on Blectrietty. 
made to touch the leaf, or retire from it to the distance of 
and inch, by means of a screw which supports it. (See 
be true, although a second leaf were, as usual, suspended 
beside the first. ; 
In a common electrometer, it is usual to have pieces of 
tin foil pasted on the glass case opposite the gold leaves. 
If attraction be exercised between. the leaves and coatings, 
when moveable, it must also be exercised by the fixed coat- 
ings thus pasted on the glass. It is therefore established, 
that when coatings, whether moveable or fixed, are em- 
obstacle to this conclusion. When equally acted. upon in all 
irections, as it must be in the case in point, air resists like 
an arch, or an elastic solid. The electric attraction may 
» 
y means of an instrument with a single leaf, since constructed, I am 
enabled to detect the electricity produced, by one contact, between ® 
enpper and zine disk, each six inches in diameter. 
