case talbot v may December where the owner of a ancient mill under the same  roof think proper to erect two new wheel they be to be consider as two mill  and to a bill bring for the tithe he can cover they with the same modus see  Grimley v Faulkingham Mod the bill be bring for tithe of a mill and a plea of  a modus of S d for the mill when it be part a cornmill and part a fullingmill  atkins in the full wheel be take away and a pair of millstone put in the room  and have be ever since a cornmill Mr attorney general for the plaintiff it be  ancient a fullingmill and the cornmill and the fullingmill be now under the  same roof and the modus can extend to cover a new erect mill for as it be  alter to a cornmill it must pay tithe in kind Mr hamet of the same side cite  roll Abr Bulstr Brownl cro James and the case of nut v chamberlain hear first  in the exchequer and afterward in the house of lord where it be determine that  every water cornmill must pay corn as a personal tithe Mr Talbot of the same  side cite bowl Abr the counsel for the defendant insist that the modus cover  the mill let the engine of the inside consist of wheel or of stone and  therefore change the work part make no variation but the modus will still  cover it as a mill though of a different kind they cite I bowl Abr and Inst  that add new stone to ancient mill will not alter the modus nor destroy it  where the stone be under the same roof they cite Carth Lord chancellor the  plea in this case must be consider both in respect to the form and substance  and upon either it can stand for as it be not ad idem it be impossible to know  to what it be applicable here be three mill charge by the bill to be work mill  the defendant plead a modus to one only call Birdlep mill all of they at  present be use as corn mill and therefore the plea be quite uncertain if this  point can be lie aside which I can do consider it next upon the substance I  will consider they as two new corn mill but under the same roof suppose first  a ancient mill under a building work with one wheel and the owner under the  same roof think proper to erect two now wheel and two new stone I be of  opinion this be to all intent and purpose two mill and he can cover they with  the same modus you may as well say he may erect another mill upon the same  stream and call it one mill atkins suppose two ancient mill in the same parish  which pay tithe in kind and another miller who have a full mill cover with a  modus shall turn it into a corn mill it will prejudice the parson in the other  mill as the new erect one will diminish the trade of those mill and the parson  suffer by those mean ought to be recompense by the payment of tithe for the  mill so convert the reason the case go upon why a modus be destroy where two  stone be erect instead of one be because the miller can grind a double  quantity consider it in another light former there be two fullingmill and a  corn mill atkins er p under the same roof and the fullingmill now turn into  two new corn mill this be just the same thing as if he have erect two new mill  the full mill can only pay a personal tithe because it be only in the nature  of a trade but where there be corn mill each be to pay a ten dish in this case  thus much must be show that there be a custom in this parish for fullingmill  to pay tithe or otherwise they do not proper pay they the only colourable  thing be it be a ancient modus for the land and that the mill be but a  accidental quality but it be not plead for the land only but as a conjunct  modus both for land and mill too and therefore let the plea be overrule