case arethusa lady dowager Clifford versus earl of Burlington Lord Clifford  all eoden die Eq can ab pl S c tenant for life with power to make a jointure  of per and upon marriage covenant to make a jointure on his wife of pound per  and afterward give a particular of land mention to be pound per and which be  settle for the jointure but prove to be but pound per and decree the jointure  to be make up pound per and by the issue in tail tenant in tail covenant to  settle a jointure and die issue in tail not bind by the covenant the Lord  Clifford by marriagesettlement be make tenant for life of several manor and  land in Ireland with power to make a jointure not exceed pound per and upon  his marriage with the Lord berkelei daughter he covenant to settle a jointure  on her of pound per and and pursuant thereunto a settlement be make and a  particular of land mention and set out for the jointure and which in the  particular give he be compute at pound per and but in truth fall short and be  not above pound per and the bill be to have the jointure make up pound per and  it be insist for the defendant that he claim under the marriagesettlement as a  purchaser and the late Lord Clifford have only a power to have charge the  estate with pound per and if he have not do it at all and have die without  execute of his power a court of equity can not have do it for he and have  raise a jointure of pound per and upon the estate though it have be reasonable  and just for he to Vernon chancery case er p have do it in his lifetime so if  he have execute his power but in part that can be extend or carry further in  equity it be a clear doctrine that this court can supply the nonexecution of a  power although it will aid a defective execution arundel v Phillpot ante p et  vide on this subject Powell on power et seq if tenant in tail covenant to make  a jointure although Vernon chancery case he may have do it by a fine or common  recovery a court of equity can relieve or decree a jointure but the court in  this case decree the jointure to be make up pound per and against the issue in  tail who be not privy to the marriagetreaty nor guilty of any fraud vide  wharton v wharton ante p fox v crane ante p