nized and known to
all scientists by the term Electric Density, the electric density being
always proportionate to the charge of electricity on a given area.

We learned also in Art. 79 that aetherial density and electrical density
were identical in relation to solar and planetary space; so that,
wherever there was the denser Aether, there was also the denser
electricity, the density of the one increasing or decreasing exactly in
the same ratio as the other increased or decreased. From aetherial and
electrical density, therefore, we have another proof of the close
identity that exists between Aether and electricity.

Again, we learned (Art. 48) that Aether possessed inertia. Here at
least, it may be thought, we shall find the first point of difference
between the two entities. Surely such an intangible, aetherial
manifestation as electricity cannot possess inertia. Let us see what
Professor Lodge has to say on the subject. In the chapter on electrical
inertia he writes (p. 89, par. 365 of _Modern Views of Electricity_): "A
current does not start instantaneously: it takes a certain time, often
very short, to rise to its full strength; and when started it tends to
persist, so that if its circuit be suddenly broken, it refuses to stop
quite suddenly, and bursts through the introduced insulating partition
with violence and heat. It is this ram or impetus of the electric
current which causes the spark seen on breaking a circuit; and the more
sudden the breakage, the more violent is the spark apt to be. We shall
understand them better directly; meanwhile they appear to be direct
consequences of the inertia of electricity; and certainly if electricity
were a fluid possessing inertia it would behave to a superficial
observer just in this way."

From these statements we learn then that electricity does possess
inertia, although there are other phenomena of electricity that would
destroy the hypothesis. But undoubtedly an electric current possesses
momentum, and it is philosophically impossible to associate momentum
with any body that does not possess inertia, as one of the factors of
momentum implies mass, even though it be a mass of an infinitesimal
form, and mass is the very essence of the property of inertia (Art. 40).

Dr. Larmor, in the work already referred to, dealing with the subject
of electric inertia, explains that it is concentrated at the nucleus of
the electron (p. 230), while on p. 202 he states: "Each electron