¶1We think that it appears, from the testimony of the plaintiff himself, that the danger of getting caught in the gearing was obvious, and that he well understood what this danger was and how it was to be avoided, and that it was from his own want of care that he was injured. See Sullivan v. India Manuf. Co. 113 Mass. 396; Rock v. Indian Orchard Mills, 142 Mass. 522; Gilbert v. Guild, 144 Mass. 601; Ciriack v. Merchants' Woolen Co. 146 Mass. 182.
¶2It is unnecessary to decide whether the presiding justice could or could not properly have permitted the plaintiff to work the machine in the presence of the jury for the purpose of showing that he had not sufficient strength to work it. It does not *262appear that any request had been made that this might be done, or that the presiding justice or the defendants understood that the plaintiff was working the machine in the presence of the jury for any such purpose. Apparently the" machine had been set up and was shown to the jury for the purpose of enabling them to understand better how the accident happened. If the exhibition had been intended to show anything else, a request should first have been made to the presiding justice, and the defendants should have had an opportunity to object to it, as well as an opportunity to test the evidence thus produced if the request had been granted, and the expei'iment should have been tried under the supervision of the presiding justice;
¶3Exceptions overruled.