It was decided when this case was formerly before this court, 1 Gray, 618, that though in the agreement of the plaintiff, authorizing the defendants to erect a dam on his land, there was no express provision as to the height to which the *381same might be raised, and as to the length of time within which it should be built, and therefore it was at the election of the defendants to build the dam as high, and at such time, as they should think fit, within reasonable limits; yet if, in pursuance of that grant, in the year ensuing its date, they built a dam capable of raising and flowing back the water of Mashapog Pond to any given height, and then left the work several years, it was a full exercise of that election, a full satisfaction of the right granted, and exhausted the defendants’ power under that grant.
One consideration in support of that view of the defendants’ rights under the grant, is this : The agreement itself fixed the price which the. plaintiff should receive for the land to build the dam upon, and the stone and earth for its construction, which perhaps would not vary much, whether the height should be more or less; but the parties contemplated a further damage by flowing the plaintiff’s other land, not taken for the dam. If the parties could not agree on this, it was to be left to Amos Hawes to decide. The amount of such damage would depend wholly upon the height of the dam and the quantity of the plaintiff’s land flowed. They could not ascertain, or begin to compute this damage until the height of the dam, and the consequent height of flowage, should be fixed by the election of the defendants. The agreement looked but to one fixing of this height, and of course one election only; and if the defendants had in 1847 built a dam calculated to raise the water four feet, and by which it had been so raised, they had made their election and exhausted their grant.
The case was ordered to a new trial, to enable the plaintiffs to prove, if they could, that such a dam had been erected, and remained as a four foot dam for several years, before the defendants did the acts now complained of. Such a trial was had, and the evidence given therein appears at great length in the report before us. Several exceptions were taken on both sides; but a verdict for the plaintiff for nominal damages having been returned by the jury, the case comes before us on the defendants’ exceptions.
The defendants’ counsel asked a witness employed to perform *382work on the flume, and to construct it, in 1847, so far as it was constructed at that time, “for what purposes the defendants said, in the same conversation,” (that is, the conversations in which the defendants had given directions to the workmen and persons employed in 1847, by way of orders and directions.) “ for what purpose they were going to have this done.” This being objected to by the plaintiff, “ the court ruled that all the orders and directions given to the workmen, and everything connected with those orders, tending to qualify or explain them, might be proved ; and the defendants’ declarations of purposes or intents were admitted to that extent; but for any purpose of introducing what the defendants said beyond that, the defendants could not put the question, to elicit a mere narrative, or naked declarations of the motives and purposes of the defendants.”
It appears to us that this ruling was sufficiently favorable to the defendants. The question was, as to what the defendants did in 1847; did they then in fact erect a four foot dam, or begin the erection of a ten foot dam, if that was within their right ? The matter to be proved was, the acts done in the erection of a dam. Admitting that orders under which the workmen did the work were part of the acts, and gave character to them, and so were admissible, the unexecuted purposes and intentions of the defendants were not material to any question before the jury.
2. The instructions to the jury were not excepted to at the time, and in general seem satisfactory. But the defendants contended that the right of election involved the question of intention ; that the question submitted to the jury should have been as to the intentions and designs of the defendants in erecting the structure of 1847 ; and that the court erred in excluding the designs and intentions of the defendants, in the directions to the jury, and in ruling that if the structure of 1847 was a dam, or could be considered as á dam, without regard to purpose, the defendants’ right was exhausted.
We can perceive no error in this. The right of election originally, no doubt, involved the question of intention; but the *383actual question before the jury was, whether that right of election had been exercised by erecting the structure of 1847; though they might, under a mistaken view of their rights, and under a grant indefinite as to time, have intended, at some future lime, as they might increase their own works, or assign their rights in part to other parties, to increase and enlarge their first structure.
3. One other exception is thus stated: “ The defendants offered to prove the conversations between them and the plaintiff at the time the contract of March 9th 1846 was signed, as to the height of the dam which the defendants were to construct, and at the same interview after the contract was signed, for the purpose of showing that it was expressly agreed that the dam should be raised ten feet; and also to show that it was the understanding of the plaintiff that the dam was eventually to be raised ten feet, and thereby to that extent to affect the construction of the contract.” This was objected to by the plaintiff, and rejected by the court as incompetent.
This evidence, in the opinion of the court, was rightly rejected. Its admission would be a violation of that plain principle which prohibits the use of paroi evidence to enlarge, diminish, alter or vary the terms of a written contract—a rule of the utmost importance to the rights of contracting parties.
The authorities cited by the defendants in support of a contrary position—Richardson v. Hooper, 13 Pick. 446 ; Munroe v. Perkins, 9 Pick. 298 ; and White v. Parkin, 12 East, 578—are all cases where, after a written agreement concluded and finished, a party has been permitted to prove a new subsequent agreement, upon a new and distinct consideration, binding as a contract, by which, assuming the former contract to be in force, the parties agree upon terms which, in their operation, may add to or change the operation of the original contract. But this is a very different thing from offering paroi evidence to prove that the original contract was different from that which the written evidence imports.
4. The only other exception worthy of notice is to the refusal of the court to allow the defendants to ask Hawes, who was an expert, “ whether, in his opinion, to raise water on Mashapog *384Pond to a height of two to three feet, thereby flowing sixty or seventy acres of land, that depth or less would be beneficial as a reservoir of water for practical mill purposes ? ” But we are of opinion that the question proposed to be put would have led to an inquiry into facts not material to any issue in this case, and that the court were right in disallowing it.
C. Allen Sf N. Wood, for the defendants,to the point of the admissibility of the defendants’ conversations with their workmen, when erecting the structure of 1847, cited Boyden v. Moore, 11 Pick. 362; Allen v. Duncan, 11 Pick. 308; Milford v. Bellingham, 16 Mass. 108 ; Thorndike v. Boston, 1 Met. 242; Kilburn v. Bennett, 3 Met. 199 ; Haynes v. Rutter, 24 Pick. 242; Walton v Green, 1 Car. & P. 621; Reed v. Dick, 8 Watts, 479 ; 1 Greenl. Ev. § 110; 1 Stark. Ev. (4th Amer. ed.) 47-49; of the conversation at the time of signing the contract, to explain the meaning of the terms used, Waterman v. Johnson, 13 Pick. 261; Dryden v. Jepherson, 18 Pick. 385; Leland v. Stone, 10 Mass. 459; Pierce v. Woodward, 6 Pick. 206; Storer v. Freeman, 6 Mass. 435; Paige v. Stone, 10 Met. 160 ; Johns v. Church, 12 Pick. 557; Hall v. Tafts, 18 Pick. 455 ; Barry v. Bennett, 7 Met. 354; The King v. Laindon, 8 T. R. 379 ; 1 Greenl. Ev. §§ 286-288; 2 Stark. Ev. 1034, note ; Gray v. Harper, 1 Story R. 574; Brady v. Cubitt, 1 Doug. 31; Davenport v. Mason, 15 Mass. 85; of what was said after the contract was signed, Richardson v. Hooper, 13 Pick. 446 ; Munroe v. Perkins, 9 Pick. 298 ; White v. Parkin, 12 East, 578 ; and of the question to Hawes, Wiggles-worth v. Dallison, 1 Dong. 201; Crafts v. Hibbard, 4 Met. 438; Knight v. New England Worsted Co. 2 Cush. 271; 1 Greenl. Ev. § 294.
F. H. Dewey G. F. Hoar, for the plaintiff.Exceptions overruled.