On the Generation of Statical Electricity. 103 
From the preceding, the following conclusions are drawn: Ist, 
the quantity of electricity generated by the rubber with the com- 
mon glass plates, has its amount nearly doubled by inductive ac- 
tion ; 2d, to maintain this increased effect, it is necessary that the 
induced electricity of the second surface be allowed to remain on 
that surface. The inductive action being a decreasing function 
of the distance, it follows, that the thinner the glass, the greater 
will be the effect; which indicates the value of the first conclu- 
sion. From the second, it appears, that if a cylinder have a damp 
interior surface, its effective action will be much diminished ; all 
eylinders should, therefore, have their interior surface perfectly 
dried, and then be sealed up air tight. If varnished with shellac, 
which has not been colored by the addition of any other sub- 
stance, the cylinder, after having been once dried, may remain 
open without material injury to its generating powers. 
The machine being in action with one rubber, it will be 
supposed that a similar one may be arranged to the second sur- 
face of the glass, and diametrically opposite to the first rubber. 
A certain quantity of positive electricity being generated by the 
second rubber, it will find itself in contact, and will unite with, 
the similar electricity induced on that surface of the glass, by 
the action of the first rubber. Hence the amount on this sur- 
face will be much increased ; and this additional quantity, acting 
inductively on the first surface, will likewise increase its excita- 
tion ; the final result being, that the electricity produced by the 
rubbers, on each surface of glass, is nearly doubled by inductive 
influence. 
It may at first appear, that by arranging points to each surface 
of the glass, nearly four times the quantity evolved by one rub- 
ber might be collected; on a closer examination, however, it will 
appear that but little more than one half of this amount can be 
rendered available ; for as soon as the free electricity of one sur- 
face is removed, that of the other, to a great extent, becomes ne- 
cessarily neutralized. ‘The plate acquiring a charge, similar to 
that produced in the experiment of the single rubber, although 
to a much less extent; andas the plate revolves, passing between 
the connected metallic faces of the rubbers, this small charge is 
neutralized. 
It has been so far assumed, that the rubbers were placed dia- 
metrically opposite ; allowing one to retain its situation, the oth- 
