This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
7. The strength of an electric current can be described as a quantity of electricity flowing continuously every second ; or, in other words, it is the rate of flow of electricity just as the current expressed in gallons per minute is the rate of flow of liquids. When one unit quantity of electricity is flowing continuously every second, then the rate of flow, or the strength of current, is one ampere; if two unit quantities are flowing continuously every second, then the strength of current is two amperes, and so on. It makes no difference in the number of amperes whether the current flows for a long period or for only a fraction of a second; if the quantity of electricity that would flow in one second is the same in both cases, then the strength of the current in amperes is the same.