The removal of tenants from the farm buildings insured and burned did not avoid the policy, unless the risk *281was thereby increased; R. S., c. 49, 20; and the increase of risk is a fact for the jury, and must be shown, in order to work a forfeiture of the policy. Lancy v. Home Ins. Co. 82 Maine, 492; Luce v. Dorchester Insurance Co. 105 Mass. 297.

That vacant buildings are more exposed to danger from fire than they would be if occupied is a fact of common knowledge, to prove which, therefore, the opinions of witnesses are incompetent and unnecessary. Mulry v. Mohawk Valley Ins. Co. 5 Gray, 541; Lyman v. State Ins. Co. 14 Allen, 329; Luce v. Dorchester Ins. Co. supra; Joyce v. Maine Ins. Co. 45 Maine, 168; Cannel v. Phoenix Ins. Co. 59 Maine, 582; Thayer v. Providence Ins. Co. 70 Maine, 531.

When the building insured is shown to be vacant, the risk of fire is presumed to bo increased; but this presumption is not conclusive, for the peculiar condition, construction and surroundings of the building may be such that the presumption will he completely destroyed and show that the risk is not increased, or even that it is decreased.

Under the statute, the burden is upon the defendant to show an increase of risk. When the vacancy is shown, it has the presumption of increase in its favor, and, unless rebutted, is sufficient to prove the fact; hut, when all the facts that picture the particular building appear, the jury must say, whether the presumption shall still prevail, or whether it is rebutted, and whether, on the whole evidence, the risk is shown to have been increased. This view is substantially illustrated by the judgment of this court in dealing with the facts in Lancy v. Home Ins. Co. 82 Maine, 492.

The evidence offered and excluded tended simply to prove that vacant buildings, as a rule, are more exposed to loss by fire than if occupied, inasmuch as the cost of their insurance is universally fixed at higher rates of premium. If the court failed to take judicial notice of the fact that the evidence tended to prove, its exclusion might have been error, for the reasons stated in Luce v. Dorchester Ins. Co. supra; hut, when the fact is known and recognized as within the common knowledge of all well-informed persons, it is useless to waste the time of a trial in proving it.

*282The buildings destroyed in this case had been left vacant for nearly a year. Upon the trial, the defendant should have been allowed either to count the presumption from vacancy in its favor, or to show facts tending to prove it. We fear the trial did not proceed upon that theory, and therefore are of opinion that a new trial should be ordered.

Motion sustained.