to it first. We have spoken of it as a fluid, but only for the sake of
illustration. As we have said, no one knows what it is, but the theory
which bids fair for acceptance is that it is a mode of motion of the
all-pervading ether. Very curious and instructive experiments are now
being carried out in Paris by Dr. Bjerkness, of Christiania, in the
Norwegian section of the electrical exhibition. This gentleman submerges
thin elastic diaphragms in water, and causes them to vibrate, or rather
pulsate, by compressed air. He finds that if they pulsate synchronously
they attract each other. If the pulsations are not simultaneous, the
disks repel each other. From this and other results he has obtained,
it may be argued that the ether plays the part of the water in Dr.
Bjerkness' tank, and that when special forms of vibration are set up
in bodies they become competent to attract or repel other bodies. This
being so, it will be seen that the power of attraction or repulsion of
an electrical body depends in the first instance on the motion set up
in the body attracted or repulsed, and this motion is, of course, some
function of the work originally done on the body. We need not pursue
this argument further. Among the most scientific investigators of the
day it is admitted that the efficiency of electricity as a doer of work,
or a producer of action at a distance, must depend for its value on the
performance of work in some one way or another on the electricity itself
in the first instance. It may be worth while here to dispel a popular
delusion. It is held very generally that electricity can be made, as,
for instance, by the galvanic battery. There is no reason to believe
anything of the kind; but whether it is or is not true that electricity
is actually made by the combustion of zinc in a galvanic trough, it is
quite certain that this electricity, unless it possesses potential, can
do no work, no matter how great its quantity. Of course, it is to be
understood that all electric currents possess potential. If they did
not, their presence would be unknown; but the potential of a current