case Perkins against Titus a custom of a manor that every tenant who shall be  admit to any copyhold estate shall pay so much as the land or tenement shall  be worth a year at the time of such admission and not more be a good custom  for though it be uncertain what the value may be yet it may be ascertain by a  jury SC Mod SC lev SC comb SC Carth SC skin SC lily Ent error on a judgement  in the common plea where they hold it a good custom to pay for a fine upon  admittance of such size denarior top quant terrae well tenement that to be  strong per and tempore ankle admission et non greater number Mr pollexfen  argue thus I know not what it mean it be altogether uncertain whether the year  before that in which the admission be or the year after or that very year in  which or common feature year or what it shall be worth to be let at for  twentyone year seven year or one year these may all be different here be a  absolute uncertainty and therefore the custom can be good it may be they be  sow with corn or be copse c a custom ought to begin itself certain davis Rep  suppose a man shall prescribe to have for toll the value of a pint of wheat it  will be uncertain no man will tell what to make of it see page case a and the  bishop of Haths case b shower KB second it be admission foret which can refer  to time pass but only to what be to come three here be a custom allege that  they who shall be admit ought to pay the fine but it be not show that any who  have be admit at any time ever pay it whereas a custom be upon time and act  pass as Edward quod bene to be for sale and not say use fuer hold ill levinz  sergeant e contra if it may be reduce to a certainty it be well enough and  that may be so here if it be at the will of the lord they have no measure to  compute it but by the value for the book say two year for a death and a year  and a half for a alienation as the land improve the fine improve and the  reason of this be find on that care which the law have of preserve the lord  interest c more be say which I can not hear and afterward on another argument  the judgement be affirm and hold that the custom be reasonable and certain  enough