Contingency With A Double Aspect

Contingency with a double aspect, is a kind of executory interest which maybe termed an alternative interest. This is an 'interest that is only to vest in case the next preceding interest should never vest in any way, through the failure of the contingency on which such preceding interest depends. As when a testator devises to A. for life; and if he have issue male, then to such issue male and his heirs for ever; and if he die without issue male, then to B. and his heirs for ever; or, where a testator bequeaths personal estate to the first son of A., and if A. should have no son, then to B.' These interests, considered in conjunction with those for which they are substitutionary, are sometimes termed 'contingencies with a double aspect.'-Smith's Compendium of Real and Personal Property, 6th Edn., p. 376.