case swift on the demise of neal and FRANCESSOPHIA his wife against roberts  Trinity g may jointtenant devise his moiety and afterward the jointure be  sever nothing pass by the will see in Jackson v Parker Ambl S c burr ejectment  and case make for the opinion of the court Richard Gilbert and FrancesSophia  his sister be jointtenants in fee of the premise in question Richard Gilbert  make his will that January by which he devise all his part right title and  interest which he have in the Temises joint with his sister FrancesSophia  Gilbert to his wife jane Gilbert and appoint his wife executrix afterward in  October Richard Gilbert and FrancesSophia agree to make partition of the  estate and for that purpose by lease and release that and that October they  convey the premise to Resiah hill and Thomas stag and their heir to and for  the use state intent and purpose therein mention concern the same that be to  say as to certain message part of the premise to the use of Richard Gilbert  his heir and assign and as to the other premise describe they be eleven  message to the use of FrancesSophia Gilbert her heir and assign and it be  ambler er p also declare by the dead that for equality ambler of partition  FrancesSophia Gilbert have pay pound to Richard Gilbert Richard Gilbert die in  without issue leave plaintiff FrancesSophia his sister and heir at law jane  the devisee of Richard Gilbert devise the premise to the defendant Q whether  the will of Richard Gilbert shall have effect as to the premise in question  Lord Mansfield chief justice Richard Gilbert have devise what he have in  jointure devise of land be not proper a will or like the Roman testament it be  not a institution of a heir if it be it will go to afterpurchasers but it be a  new limitation of the estate by a revocable act not take effect till after his  death by construction of law on customary devise a man can not devise what he  have not if will of jointtenant before the statute of devise be to operate at  all it must have operate as a severance by refer back to the will but the law  say jointtenancy can be sever in that manner Perkins as far as any stress can  belaid on such lose say be to be understand that a devise be not ineffectual  as have nothing on which it can operate but on account of jointtenants right  of survivorship as to what follow it be not warrant by the place to which it  relate I think on the statute of h be can not have devise to the prejudice of  his companion the stat h make it clear to many purpose both the time of make  and the death be to be consider to make a true construction here he have not  the power at the time of make his will as to the partition it be so far from  malt this devise good suppose it not to be so in its commencement that I  apprehend even if it half be give in its commencement the partition will have  be a revocation for the estate must continue the same it be at the time of  make the will any thing that make a alteration in it amount to a revocation  even though do with a intention to substantiate the will Ro Abr if one devise  land and after make a feoff to the use of his will it be a revocation so if  one covenant to levy a fine to the use of such person as he shall name by his  will he then make his will and devise his land and ambler afterward levy a  fine in performance of his covenant it be a revocation if one consider the  nature of partition even in case of tenancy in common it work a alteration of  estate while the estate stand in common each be seize of the whole in common  with his companion the instant of the partition each have a sole estate in a  moiety in case of jointtenancy partition defeat the right of survivor and give  each a separate estate attend with different quality as to the action and  remedy to which they be entitle the act of partition be inconsistent with the  will by the will he give the estate to his wife by the partition to himself  and his heir note vide p W n tenant in common devise and then a partition and  fine and hold nor evocation Luther v Kirby a mere partition whether by  compulsion or agreement be not a revocation but the slight addition as a power  of appointment prior to the limitation of use be sufficient knoll v Alcock Ves  ware v more mad Rawlins v burgess v b see Harmood v Oglander Ves Goodtitlev  Otway Bos pull maundrell v maundrell Ves Wilmot justice it be a clear case  stat h operate as give a power to dispose by this mode must be taken strict  all the determination go upon the testator have land at the time of the will  here the testator clear have not a devisable estate at the time of the will  subsequent event will have effect upon the operation of will as where a estate  for life remainder in fee and the tenant for life die before the testator the  remainder passes in possession but as to the power the party must have it at  the time of the will the case do not warrant the observation in Perkins sir  Joseph Yates justice case clear jointtenant can devise a man can devise what  he have not at the time it must have the land plain from the manner of plead  videlicet that he be seize and be seize devise judgement ambler er p