231. Commencement of the term.

It is sufficient if the commencement of the term can be ascertained with certainty at the time when the lease is to take effect in possession1. Hence the term may be made to commence after the failure of specified lives2, or upon the occurrence of a future contingent event3. Where it is to take effect after the expiration of a previous term, and the previous term is surrendered or forfeited, the lease takes effect on the surrender or the forfeiture, as the case may be4; and, if the previous lease has already come to an end, or if it