“The plaintiffs filed their bill on the equity side of the court setting forth that the plaintiff Ogle is the original inventor of a new and useful improvement in the plough, for which he obtained a patent in the year 1818. That in the year 1824, he, by deed, and for a valuable consideration, assigned and conveyed to the other plaintiff all his exclusive right to the said invention, with the liberty of making, constructing, using, and vending the same toothers to be used, in and throughout the state of Pennsylvania, with a power of attorney for those purposes.