1. We understand the rule of practice to be well settled, that if a party who has had notice to produce a paper at the trial refuses to do so, and the other party introduces secondary evidence of its contents, the party so refusing cannot *99afterwards produce the paper in evidence, either to contradict such secondary evidence, or in support of his own case. Doe v. Cockell, 6 C. & P. 525, 527. Doe v. Hodgson, 12 Ad. & El. 135. 1 Greenl. Ev. (10th ed.) § 560, n. 3. And the rule seems to be a just and reasonable one. It should not be permitted to a party to compel his adversary to avail himself of imperfect means of establishing a fact, the best evidence of which he chooses to prevent him from using; and then to avail himself of the proof which makes all other evidence useless. Any other rule would make it for the interest of a party in all cases to withhold important documents, with the certain reliance that he could in no event be prejudiced, and with a chance of obtaining an unfair advantage. For if the secondary evidence should prove the contents of the paper with complete exactness, the case would stand as well as if it had been produced. If it tended to show something more unfavorable to the other party than the exact truth would have done, the subsequent production of the paper itself would control and do away with the effect of it. And if the evidence fell short of establishing all which the paper contained adverse to the interests of the party who had it in his possession, he could allow the jury to be misled, and gain an advantage from evidence which he knew to be untrue.

But though the admission of the note in evidence for the defendant, after he had been notified by the plaintiffs to produce it, and had refused to do so, was irregular, it gives the plaintiffs no just ground of exception, unless it appears that they were prejudiced by it. Burghardt v. Van Deusen, 4 Allen, 374. Hackett v. King, 8 Allen, 144. The purpose of granting a new trial is not to obtain mere theoretical accuracy, but to secure substantial justice. And on examining the case carefully, we do not find that the plaintiffs were injured by the production of the note. They complain that they were obliged to call an adverse witness; but that was because the note was withheld, not because it was afterward shown to the jury. The plaintiffs wished to prove that payments were made upon the note within six months of the insolvency of the promisor; and to do this, *100they wished to use the indorsements upon the note. The defendant had previously given a copy of the note, and set forth the indorsements upon it truly, in his answer. The note, when produced, tended to establish the fact which the plaintiffs sought to establish. It was better evidence for them than the evidence of their witness, and its production was a benefit rather than an injury.

2. That the defendant was not precluded from showing that the indorsements upon the note were not correct, because he had used it in evidence, is too plain to require the citation of authorities. The indorsement upon a note of payments of money is merely a receipt, and open to explanation or contradiction by paroi.

3. The exception taken to the instructions given to the jury cannot be sustained. The failure of Poole to pay the debt due to the defendant would not necessarily, as a matter of law, constitute insolvency, or be notice to the defendant of insolvency; although it would be evidence tending to 'show it. And the instruction that the plaintiffs, in order to avoid the payments made upon the note, and recover them from the defendant, must not only show that they were made when the debtor was insolvent or in contemplation of insolvency, and when the defendant had reasonable cause to believe it, but also that the defendant had reasonable cause to believe that the debtor intended a preference, although not true as an abstract statement of the law, was correct as applied to the evidence in the case. The statute provides that, to avoid such payments, the defendant must have had reasonable cause to believe that they were made in fraud of the insolvent law, or in violation of its provisions. Gen. Sts. c. 118, §§ 89, 91. But the only violation of the provisions of the insolvent law which the plaintiffs charged or attempted to prove, or of which there was any evidence, was an intention to prefer the defendant. There was, therefore, no substantial error in directing the attention of the jury exclusively to that.

Exceptions overruled.