The competency of the witness was a matter of fact, to be determined by the court at the trial. Jones v. Tucker, 41 N.E. 546; Dole v. Johnson,50 N.H. 452; Ellingwood v. Bragg, 52 N.H. 488. But the ruling, that, as a matter of law, opinion is not competent evidence on the subject of inquiry in this case, was erroneous. Some or all of the members of the jury may not need the opinion of a witness in relation to the quality of a load of hay which they have seen and thoroughly examined; — but the law does not exclude the opinions of witnesses on that subject. Hardy v. Merrill,56 N.H. 227, 247; Brown v. Marr, 55 N.H. 448, 449.

If the jury in this case did not take a view of the plaintiff's dam, a description without opinion might convey a very imperfect idea of the fact which the defendant was entitled to prove. If they took a view in *Page 197 February, when the case was tried, it could not be held, as matter of law, that they were all so skilled in the construction of a proper sluice for running logs, at any time, there or elsewhere, that they could not be informed by the opinion of a witness capable of forming a sound judgment on the subject.

Verdict set aside.

BINGHAM and ALLEN, JJ., did not sit.