Mr. Chief Justice Bean,
after stating the facts, delivered the opinion of the court.
1. It is conceded that a court of equity has jurisdiction to enforce the specific performance of a parol contract for the conveyance of an interest in letters patent, when issued, for an invention or device patentable under the laws of the United States : Searle v. Hill, 73 Iowa, 367" court="Iowa" date_filed="1887-12-10" href="https://app.midpage.ai/document/searle-v-hill-7103108?utm_source=webapp" opinion_id="7103108">73 Iowa, 367 (5 Am. St. Rep. 688, 35 N.W. 490" court="Iowa" date_filed="1887-12-10" href="https://app.midpage.ai/document/searle-v-hill-7103108?utm_source=webapp" opinion_id="7103108">35 N. W. 490); Somerby v. Buntin, 118 Mass. 279" court="Mass." date_filed="1875-09-06" href="https://app.midpage.ai/document/somerby-v-buntin-6418185?utm_source=webapp" opinion_id="6418185">118 Mass. 279 (19 Am. Rep. 459); Burr v. De La Vergne, 102 N.Y. 415" court="NY" date_filed="1886-06-01" href="https://app.midpage.ai/document/burr-v--de-la-vergne-3580266?utm_source=webapp" opinion_id="3580266">102 N. Y. 415 (7 N. E. 366); Fuller Mfg. Co. v. Bartlett, 68 Wis. 73 (31 N. W. 747, 60 Am. Rep. 838).
2. And, as a matter of fact, there is but little conflict in the testimony. Some time prior to March 1, 1900, the defendant conceived the idea of an invention and device for easily and quickly attaching and detaching a plowshare and point to and from the moldboard of a plow, but had not put it into practical form. While working in the shop of the plaintiff, who is a blacksmith in Union, he explained this idea to him ; and the plaintiff, after thinking it over, concluded that it could be developed and the invention patented. Both parties thereupon set out to perfect the invention and obtain a patent. At plaintiff’s suggestion, defendant made a wooden model, using the plaintiff’s shop, tools, and materials, while he made an iron one. After the models were completed, defendant forwarded the wooden one to a fiivm of patent lawyers in Washington, to whom he *417wrote in the name of himself and the plaintiff, asking them to examine the records of the patent office to ascertain whether the invention was new and patentable. In due time he received an answer from the attorneys, saying the examination had been made, and that they thought a patent could be obtained, and inclosing a circular, in which it is stated that an application for a patent must be made in the name of the inventor alone. The defendant thereupon,' without the plaintiff’s knowledge, advised the attorneys that plaintiff had no interest in the invention, but that he himself was the sole inventor, and directed the application for the patent to be made in his name, which was accordingly done. As soon as the plaintiff learned of this, he objected to the change in the application, and insisted on his right to share equally with the defendant in the invention and patent. The defendant thereupon called upon one Cameron, and told him that he had made a mistake in letting plaintiff in on the matter, but now desired to settle the dispute as best he could. Cameron advised that it be settled by dividing the territory to be covered by the patent; defendant taking a part thereof, and plaintiff the remainder. The defendant assented to this, and authorized Cameron to submit the proposition to the plaintiff and arrange for a meeting between them, to which plaintiff agreed; and in pursuance thereof he and defendant met at the office of Mr. Lomax on March 28 for the purpose of thus adjusting their differences. At that time the plaintiff paid to the defendant, and he received, one half the fees and expenses advanced by him on the application for the patent. The parties were unable to agree, however, concerning the division of the territory, although no question seems to have been made as to their respective interests.
*418The principal contention for the defendant is that the evidence is so indefinite and uncertain as to the contract between the parties — especially as to the interest the plaintiff was to have in the invention — that a court of equity can not decree an enforcement thereof. The argument is that, before a court can decree the specific performance of a contract, the terms thereof must be distinctly shown, so as to leave none of the essential details in doubt or uncertainty. And such is the general rule of law. But here there is no question as to the contract. The plaintiff testifies that they were to make and own the invention and patent “in partnership” or “as partners,” while the defendant says that the plaintiff was to have an interest therein sufficient to recompense him for the use of his tools, but that there was no agreement that he should have a half or any other definite interest. It is therefore admitted that plaintiff was to be jointly interested with defendant in the invention and the proposed letters patent, and the only question is as to the nature and extent of such interest. Upon this point the agreement was, perhaps, indefinite. But we think the testimony and attendant circumstances show that they were jointly interested in the patent. The plaintiff says they were to own it as partners or in partnership, and immediately after the wooden model was made, and before it was sent to Washington, the defendant, in talking to the witness Cameron about the matter in the presence of one Reeves, said : “Mr. Gius is with me on it. Mr. Gius is a partner on the plowshare.” And he made substantially the same statement to two or three other persons. Again, after the controversy between them had arisen, the plaintiff paid to the defendant one half the amount advanced by him for fees and expenses in making the. application; and, so far as the record shows, it was not until after the *419failure to agree upon a division of the territory covered by tlie patent that the defendant ascertained that plaintiff was not an equal owner with him.
8. Where two or more persons enter into a joint venture of this kind, the prima facie inference of law is that they are equally interested, and entitled to an equal share therein ; and, where the contrary is alleged, the burden of proof is on him alleging it: Robinson v. Anderson, 7 De Gex, M & G. *239 ; Webster v. Bray, 7 Hare, 158. In view of this rule, we are of the opinion that, under the testimony, the plaintiff is entitled to an undivided half interest in the invention referred to in the record, and in the letters patent issued or to be issued therefor, and that the decree of the court below should be reversed, and one entered here in accordance with this opinion.
Reversed.