4. The cy-près doctrine.

The doctrine of cy-près1, as applied to limitations void under the rule in Whitby v Mitchell, was a rule of construction of wills2, by which, in a proper case, effect could be given to a testator's intention by substituting an effective entailed interest for a devise which went beyond the limits allowed by law. The doctrine operated in the following manner. Where, in a will, there was a limitation of real estate for life to a person unborn, with remainders in tail to his children, or with successive remainders for life to his children indefinitely, and the testator's intention