The objection to the question to the witness Allen was not to its form, nor to its mode of bringing to his attention the facts upon which he was asked for an opinion, but that expert testimony could not be received upon the subject to which it related. The witness was admitted to be an expert of large experience in the construction of sewers and water*243works, and he must be presumed to' have known whether gates, flaps, or other appliances could be used to prevent the influx of water from a drain into a cellar, and if they could, whether they would work satisfactorily, and whether it would be easy or difficult to put them in. His study and experience may be presumed to have also taught him the probability or improbability that, from sewers constructed as those in that neighborhood were, water would set back into house drains during a flood.

We are of opinion that these are not matters of common knowledge, and that the opinion of an intelligent expert may have been valuable at the trial upon the question what precautions were reasonably necessary on the part of the plaintiff to prevent a flow of water from the drain into his cellar. Moulton v. McOwen, 103 Mass. 587. Commonwealth v. Choate, 105 Mass. 451. Kershaw v. Wright, 115 Mass. 361. Hand v. Brookline, 126 Mass. 324. Exceptions overruled.