2 Bl. Rep. 1010. And it is also observable, that there was not one of these cases in which the ancestor took the legal estate of freehold. To sum up the distinctions between vested and contingent remainders, it maybe observed, that wherever the preceding estate is limited, so as to determine on an event which certainly must happen; and the remainder is so limited to a person in esse and ascertained, that the preceding estate may, by any means, determine before the expiration of the estate limited in remainder, such remainder is vested. Berr-ington v. Parkhurst, 3 Atk. 135. Willes, 327. 6 Bro. P. C. 352. On the contrary, wherever the preceding estate (except in the cases before-mentioned, as exceptions to the descriptions of a contingent remainder) is limited so as to determine only on an event which is uncertain, and may never happen; or wherever the remainder is limited to a person not in esse, or not ascertained; or wherever it is limited so as to require the concurrence of some dubious uncertain event, independent of the determination of the preceding estate and duration of the estate limited in remainder, to give it a capacity of taking effect, then the remainder is contingent. Fearn. Cont.Rem. 330, 331.

With respect to the effect of contingent remainders intervening between the particular estate and the remainders over, in making them contingent, it is observable, that wherever a contingent remainder is limited, which is followed by another limitation over, if the contingent limitation be not in fee, the subsequent limitation may be vested, if it be made to a person in esse. Fern. Cont. Rem. 338. As upon a feoffment to the use of the feoffees during the life of A., and after his death, to the use of his first and other sons successively in tail, with several remainders over; and A. having no sons at the time of the feoffment, it was resolved that all the uses limited to persons not in esse were contingent, but the uses to persons in esse were vested immediately; and that the contingent uses when they should come in esse, would vest by interposition, if the estate for life, which ought to support them, was not disturbed. Chudleigh's case, 1 Rep. 137. And where, in the same conveyance, an estate for life is limited to a person, and after that a contingent remainder to another, followed by a remainder to the heirs or heirs special of the first tenant for life, this last limitation shall be esteemed executed only sub modo; that is, in such manner as to open and separate itself from the first estate for life, when the contingency happens. Lewis Bowles' case, 11 Rep. 80. The preceding cases are instances, where the contingency of the intervening remainders arose from their being limited to persons not in esse. But if there be a remainder limited to a person in esse, so as to depend on a could pass to the tenant of the particular estate and at the expiration of his estate could pass from him to the remainder-man. Again, in the case of an estate less than freehold followed by a vested remainder, the contingent event, if the same contingency be not considered as extending to the subsequent limitations, such of those limitations as are to persons in esse may be vested; as in the case of Napper v. Sanders, Hutt. 119; where, upon a feoffment made by A. to the use of himself for life, and after to the use of the feoffees for eighty years, if B. and C. his wife should so long live; and if C. survived B. her husband, then to the use of her for life; and after her decease to the use of D. in tail, remainder over; though it was agreed, that C.'s estate for life was contingent, on the event of her surviving husband, yet it was held, that the subsequent remainders were vested. Et vid. Tracey v. Le-thulier, 3 Atk. 774. Ambl. 204. Whitfield v. Bewit, 2 P. Wms. 240. So a subsequent contingent remainder may become vested in interest before a preceding one, which will be no obstruction to its so vesting. Uvedale v. Uvedale, 2 Roll. Abr. 111. But where there is a contingent limitation in fee absolute, no estate limited afterwards can be vested. Lod-dington v. Kime, 1 Salk. 224. Ld. Raym. 208. Doe v. Holmes, 3 Wils.237, 241. 2 Bla. 777. Goodright v. Dunham, Dougl. 251. Doe v. Perryn, 3 T. R. 484. It seems, however, that a contingent interminable fee, devised in trust for some special purposes only, will not prevent a subsequent limitation to one in esse from being vested. See Tracey v. Lethulier, supra. Fearn. Cont. Rem. 342. Sed vid. n. (a), 6th edit. p. 226. And where estates are subject to a power of appointment in the first taker, with remainders over in default of such appointment, such a power does not suspend the effect of the subsequent limitations, and keep them in contingency. Fearn. Cont. Rem. 343, 344. Et vid. acc. Maundrell v. Maundrell, 7Ves. 567. 10Ves.246. Sugd. Pow. 141. It is further to be observed, that although a fee cannot, in conveyance at common law, be mounted on a fee, yet two or more several contingent fees may be limited, merely as substitutes or alternatives, one for the other, and not to interfere; but so that one only can take effect, and every subsequent limitation be a disposition substituted in the room of the former, if the former should fail of effect, Loddington v. Kyme, 1 Ld. Raym. 203. Bar-nardiston v. Carter, 3 Bro. P.C. 64. Doe v. Holme, 2 Bla. 777. Fearn. Cont. Rem. 547, 550; as where a will was made in these words: "I give my messuage, etc. to my son J. S. for his life, and after his death unto all and every his children equally, and to their heirs; and in case he dies without issue, I give the said premises unto my two daughters and their heirs, equally to be divided between them; it was determined, that both the devisees were contingent remainders in fee. Good-right v. Dunham, Dougl. 265. Et vid. Doe v. Perryn, 3 T. R. 484. Ives v. Legge, cited 3 T. R. 488. Crump, d. Woolley v. Norwood, 2 Marsh. 161. Such limitations are sometimes called limitations on a contingency with a double aspect; sometimes limitations on a double contingency; and sometimes concurrent or contemporary limitations; as to which denominations see Mr. Douglas's remainder-man could take the seisin. In the case, however, of an estate less than freehold followed by a contingent remainder, neither the tenant of the particular estate nor the contingent remainder-man would be note (2) Doe v. Fonnereau, Dougl. 504. But in all cases where the first contingent remainder is in fee, or where there are concurrent remainders, if the first remainder becomes vested, all the subsequent remainders are void: for then they become remainders expectant on the determination of an estate in fee-simple. 2 Cru. Dig. 286. Keene v. Dickson, 3 T. R. 495. As to the cases wherein a contingency annexed to a preceding estate is, or is not, considered as a condition precedent to give effect to the ulterior limitations, such cases may be distinguished into three classes. 1st. Limitations, after a preceding estate, which is made to depend on a contingency that never takes effect. 2dly. Limitations over upon a conditional contingent determination of a preceding estate, where such preceding estate never takes effect at all. 3dly. Limitations over upon the determination of a preceding estate by a contingency, which, though such preceding estate takes effect, never happens. Fearn. Cont. Rem. 355. 1st. The cases of Napper v. Sanders, and Tracey v. Lethu-lier, above mentioned, appear to fall under the first class; in which cases, we have seen, the contingency affected only that estate, to which it was first annexed, without extending to the ulterior limitations. Et vid. Bradford v. Foley, Dougl. 63. Horton v. Whitaker, 1 T. R. 346. The construction in these cases, as to the restriction of the contingency, to the estate first hinged upon it, appears to depend on the testator's apparent intention, not to extend it further. For, wherever there is no apparent distinction in view in this respect, between such estate, and those which follow it, the contingency, it seems, will equally affect the whole ulterior train of limitations. Davis v. Norton, 2 P. Wms. 390. Doe v. Sheppard, Dougl. 75. Fearn. Cont. Rem. 358. 2d. As an instance of that class, where subsequent estates were limited, on a conditional determination of a preceding estate, and such preceding estate never took effect at all; we may refer to the case of a devise to trustees for eleven years, remainder to the first and other sons of B. successively in tail-male, provided they should take the testator's sirname; and, in case they or their heirs should refuse to take the testator's sirname, or die without issue, remainder to the first son of C, remainder over. B. died without having had any son, C. had a son at the time of the devise. The court did not agree as to the validity of the devise to the first son of B., being after a term of years, without any preceding freehold to support it; but resolved that the subsequent limitation to the first son of C, who was then in esse, and capable, took effect; and that the preceding limitation to the first son of B., or the condition thereto annexed, did not operate as a precedent condition which must happen, to give effect to the subsequent limitation to the son of C, but was only a precedent estate attended with such limitation. Scat-terwood v. Edge, 1 Salk. 229. Of the same opinion was Lord Hardwicke, in the case of Ave-lyn v. Ward, 1 Ves. 422; who said he knew of no case of a remainder or conditional limitaable to take seisin and therefore the contingent remainder would fail.