the current flowed from the positive terminal of a circuit, back
to the negative terminal. These two theories are, therefore, in
contradiction to one another, but due to the fact that the whole
foundation and operating principles in the development of elec-
trical engineering were founded on the old theory, this custom
cannot well be changed in all cases, so we must still speak of
the current as flowing from the positive terminal to the negative
in some cases, covering the action of motors, generators, trans-
formers, batteries, etc., but it is well to bear in mind that the
thing that really flows in the wire or circuit as we know it
today is a stream of electrons from the negative to the positive
terminal.
The cause of this flow or movement of electrons is the
chemical action within the battery which maintains a push or
constant pressure (voltage) at the ends of the copper rod. This
action would be the same if the pressure was provided by other
means such as a generator because the battery or generator is
acting as we might say like a pump for pumping electrons
through the complete circuit.
We can demonstrate this action very nicely by comparing
it with water in a pipe. The length of the pipe will not matter.
For our demonstration the pipe will have to be full of water
just as a wire is full of electrons. Returning to our pipe full
of water--we force a quart of water into one end by the pump.
What happens at the other end? Naturally a quart of water
will be forced out. But the water forced out is by no means
the same water that we put in. This is, of course, a very
crude illustration, but we want to get very clearly in your
mind that electrons from a battery do not travel very rapidly
and yet the effect is almost instantaneous throughout the cir-
cuit. The electron itself does not go through 186,000 miles of
wire in a second. But it causes a disturbance of the electrons
and the disturbance is felt instantaneously throughout the
entire circuit.
For instance, when you push an electric light button, an
electric circuit is closed and a current starts to flow through the
circuit immediately. Remember that this flow of electricity is
nothing but a continued disturbance and movement of the elec-
trons in the circuit.
Now we are going to leave the electron and our study of the
nature of electricity for a while in order to take up in this first
lesson other fundamental principles of Radio. Our purpose is
