The word dynamo, meaning power, is one transferred from the Greek to
the English language, hence the primary meaning of the term signifying
the electric generator is, the electric power machine.
The word generator is derived from a word meaning birth giving,
hence also the dynamo is the machine generating or giving birth to
electricity.
[Illustration: FIG. 217.—See page 251.]
Again, the dynamo is a machine driven by power, generally steam or
water power, and _converting the mechanical energy expended in driving
it, into electrical energy of the current form_.
To summarize, the dynamo-electric generator or the dynamo-electric
machine, proper, consists of five principal parts, viz: