Power, an authority given by one person to another to act for him, or to do certain acts, such as granting leases, raising portions, or the like, also to modify the use of an estate which he has at his disposal; in short, it may be aptly defined as "an authority enabling one person to deal with an interest which is invested in another." Power, in engineering, is the rate at which work is done by any motor. If an engine is capable of doing 33,000 foot-pounds of work per minute, it is said to develop one horse-power. which unit was originally intended to represent the rate of working of a horse. In the C.G.S. system the unit of power is the watt, which is ten mega-ergs per second; this is equivalent to a current of one ampere working through a resistance of one ohm, and is equal to T ff horse-power.