298 On the Theories of the 
electricities of the first and last plates of the 
series, a pile of 50 pairs will not be exaetly 
half so energetic as one of 100 pairs, but some- 
what less; because the differences in the terms 
of a geometrical series increase as the terms 
increase. But, in the present instance, there 
is great reason to apprehend that the ratio of 
1 to m is very nearly that of equality. If so, 
the geometrical series for a moderate number 
of terms, will scarcely differ from an arith- 
metical one. ‘This accords very nearly with 
experience ; for it has been determined by _ 
Volta, that if a combination of 20 pairs of 
plates produce a given effect on the electro- 
meter, a series of 40 will produce double the 
effect ; one of 60 triple, and so on. At the 
same time it is probable that the electric 
intensity of the plates, composing each pair, 
relatively to one another, continues unaltered, 
notwithstanding the change in their absolute 
quantities of electricity. 
When a connection is established between 
the two extremitics of a series like the above, 
for example between the third zinc plate, or its 
contiguous cell, and the first copper plate, the 
opposite electricities tend to an equilibrium. 
The third pair loses a share of its electricity, 
which is gained by the first; and the intermedi- 
ate pair, being placed between opposite forces 
