"From what?"
"From the copper?"
"Is that better than iron?"
"Copper should be used for several reasons; first, because electricity travels through a copper wire more easily than through iron, and second, for the reason that copper is more ductile than iron, and can be drawn into a wire with greater facility."
"Doesn't electricity flow through different substances at the same rate of speed?"
"Yes; but it retards the amount or the force."
"You say, 'Amount' or 'Force.' I can understand that if applied to water, that there might be a large or small quantity of water, or a greater or less pressure, but I do not see how this applies to electricity."
"In measuring the pressure of water, calculation is made by taking the height of the water in the tank. For every 28 inches in height a column one inch square weighs one pound. This represents the force of the water when it issues from the orifice below. Now the orifice may be large or it may be small. The amount or quantity which flows out is dependent on the size of the opening. Electricity is measured in a somewhat similar manner. What is called 'Volts' is the same as the force in the tank—that is, voltage means the pressure. Amperage, on the other hand, refers to the amount of current which is passing, and a greater quantity will pass over a large wire just the same as a greater amount of water will flow through a large than a small pipe. Is this perfectly clear to you?"
"Yes; I understand the difference, now."
The drawing of wire is not a difficult task where facilities are at hand, but it must be remembered that all their tools were of the crudest kind. Harry had prepared a number of bars of copper, each having been beaten out to form pieces about ten inches long and a half inch thick. A steel plate about three-eighths of an inch thick, two inches wide, and six inches long, had a number of holes bored through it, the largest hole being a half inch in diameter, and gradually increasing in size, the smallest being about a sixteenth of an inch in diameter.