A species of estate in expectancy, created by opera^ tlon of law, being the residue of an estate left in the grantor, to commence in possession after the determination of some particular estate granted out by him. 2 Rl. Comm. 175; 2 Crabb, Real Prop. p. 978, 8 2345. The residue of an estate left in the grantor or his heirs, or in the heirs of a testator, commenc-lng in possession on the determination of a particular estate granted or devised. 1 Rev. St N. Y. p. 71S, (723.) $ 12. An estate in reversion is where any estate is derived, by