RothrooK, J.
A question is raised as to the manner in which this cause is to be tried in this court; — whether upon 1. PRACTICE in supreme court: trial de novo where cause tried as equitable action below. errors, or de novo on the evidence, which has been reduced to writing.
It appears from the record that the whole of the evidence was reduced to writing on the hearing, which was had before the court, and, by an order entered in the case, the evidence was taken down by the official short-liand reporter, was made a part of the record, and on the evidence then introduced the case was taken under advisement to be argued in vacation, and judgment and decree entered in vacation. This order was made at the March term, 1885; both parties being present. At the September term of the same year the cause was continued by *502consent, for tbe reason, as stated in the order, that the record had not been submitted to the court. At the term held in February, 1886, the cause was resubmitted and taken under advisement, and judgment and decree to be entered in vacation. It is apparent from the record that the cause was tried below as an equitable action, and it must be so tried here. Van Orman v. Merrill, 27 Iowa, 476; Balch v. Ashton, 54 Id., 123; Richmond v. Dubuque & S. C. R. Co., 33 Id., 422; Blough v. Van Hoorebeke, 48 Id., 40. The evidence having been certified as required by law, we shall therefore proceed to consider the case as triable de novo in this court. .
The aj>pellant insists that the court erred in sustaining a motion to strike out a part of an amendment to the answer, but a-.careful examination of the pleading convinces us that the portion struck out might be regarded as redundant; and we think the motion vvas properly sustained.
The first branch of tho equitable defense, set up by the defendant is that the contract in question does not express 2. equity: of writing: evidence nee-essary. the true intent of the parties, but that the design was to put into the agreement “that defendant, , y . . , or Ins assignees, should have the right to prospect said land, and see if there was any coal thereunder, and, if it was proven there was not, there should be no royalty or money paid;” that this was the intention at the time the contract was made, but that it was “omitted from the written agreement by mistake or oversight. Defendant therefore asks that the written agreement or conveyance be reformed so as to express the real intent of the parties at the time, as indicated above.” It is an old and well-established rule that, before a court can disturb the provisions of a written agreement for the purpose of reforming it, there should be clear and convincing evidence (1) that the written instrument did not, at the time of its execution, set forth the true intent of the parties; (2) that the failure to make the instrument express such intent arose from oversight or mistake iu drafting the instrument.
*503It does not seem to us clear from tbe evidence that there was any intent, at the time of the execution of the writing, that any such provision as claimed by defendant was intended to be inserted. On the contrary, all the negotiations proceeded in the belief that' there was coal on the premises, and the writing was drawn in accordance with such negotiations. There was not sufficient evidence to warrant the court in disturbing the provisions of the contract.
It appears very clear, however,-from the evidence, that the lease or conveyance was executed, delivered and received mutual’mistake as to ex-considera-ti°n. under the belief that there was coal underlying the premises, and that the same could be mined, 1 ’ It is equally clear from the testimony that there D0 coa^ The lease was therefore entered into by the parties through a material honest mistake of fact, of vital importance to the validity of the contract. Both parties were dealing in regard to something they supposed to be in existence so far as either had any knowledge. Against such- a mistake equity will grant relief. 1 Story, Eq. Jur., 142-144; Allen v. Hammond, 11 Pet., 63 (70); 2 Kent, Comm. (10th Ed.,) 643. There being, therefore, a total failure of consideration arising out of mutual mistake, the plaintiff is not entitled to recover of the defendants.
KeVEESED.