Of the same value. Sometimes a condition must be literally accomplished in forma specifica; but some may be fulfilled by an equivalent, per oequi polens, when such appears to be the intention of the parties; as, I promise to pay you one hundred dollars, and then die, my executor may fulfill my engagement; for it is equivalent to you whether the money be paid to you by me or by him. In patent law. Any act or substance which is known in the arts as a proper substitute for some other act or substance employed as an element in the invention, whose substitution for that other act or substance does not in any manner vary the idea of means. It possesses three characteristics: It must be capable of performing the same office in the invention as the act or substance whose place it supplies; it must relate to the form or embodiment alone and not affect in any degree the idea of means; and it must have been known to the arts at the date of the patent as endowed with this capability.