The building inspector appeals from a final decree permitting the defendant to keep on his premises as he had “for several years” one pony for his own use which the judge found was not commercial. The premises are in a “single-family . . . district.” The judge found that the area “is still a rural area,” that there was no evidence of nuisance, that the keeping of one pony would not substantially derogate from the spirit and purpose of the by-law or be detrimental to the public good. The section of the by-law relied upon by the plaintiff affords no guide in the circumstances. The holding in Pratt v. Building Inspector of Gloucester, 330 Mass. 344, 346-347, is not applicable.

Decree affirmed.