187. Agency terminated by effluxion of time.

Termination by operation of law may take place by effluxion of the time which may be fixed for the continuance of the agency by the parties or by custom or usage of the particular trade or business1. It is not necessary that the time for the continuance of the agency should be expressly stated. It may be presumed from the nature of the authority; for example, when a power of attorney recited the fact that the donor was about to go abroad, it was held to be impliedly revoked on his return home