delivered the opinion of the Court:

Thus it will be observed that the product of appellant is within the same general class as that of appellee. “The intent of the statute is to protect the rightful owners of trademarks in their valuable property rights; and it seems to tax the courts to the utmost to protect those rights against the ingenuity of counsel and the designs of sharp competitors. A mark should be denied not only when used upon goods of the same descriptive properties as a similar registered mark, but when used on goods belonging to the same general class.33 Walter Baker & *31Co. v. Harrison, 32 App. D. C. 272. It is no answer that appellant has not manufactured a steam car heating system upon which thermostatic steam traps are used, or even that its trademark has not been applied directly to the thermostatic devices in use. They are a part of its system to which the mark is applied, and it is at any time within their power to apply it to any appliance of that kind they may manufacture; and this is true should they extend their manufacture to electrically heated steam car heaters. Indeed, it appears that such heating-apparatus may be manufactured by appellant. It, therefore, has the right to extend the use of its mark accordingly. Appellee should not, in justice, be permitted, by the adoption and use of this mark, to invade the present field of appellant, or the domain to which it may legitimately extend the use of its mark. In Florence Mfg. Co. v. Dowd, 101 C. C. A. 565, 178 Ted. 73, the court, considering the right of the owner of a mark to extend its use, said: “But it is urged that as the complainant did not manufacture tooth brushes at the time the defendants entered the field, it cannot be injured by the sale of tooth brushes by others. We do not think the conclusion follows. The complainant had acquired a reputation as the manufacturer of high-grade toilet brushes; it certainly had a right to include tooth brushes at any time, and when it did so, purchasers who were acquainted with the high character of its goods would quite likely purchase its tooth brushes, deeming its previous reputation a guaranty of excellence. In other words, the complainant did not abandon the right to make ffveepclean’ tooth brushes because it did not at the outset make such brushes, as well as other varieties of toilet brushes.” To the same effect are Collins Co. v. Oliver Ames & Sons, 20 Blatchf. 542, 18 Ted. 569; American Tobacco Co. v. Polacsek, 170 Ted. 117.

It is no excuse that appellee’s officers testified that they were not aware that appellant applied the mark to steam heaters. They conceded they knew of the existence of appellant company. In fact, they were competitors to the extent of both having-furnished car-heating systems for the New Haven .Railroad Company. Appellee knew of the general use of the mark by *32appellant,, and it should have advised itself fully before appropriating the mark. It is hard, even in the absence of evidence to the contrary, to attribute good faith to one who knowingly appropriates the mark of another, to be used upon the same general class of goods. As Mr. Justice Robb said in Phœnix Paint & Varnish Co. v. John T. Lewis & Bros. Co. 32 App. D. C. 285 : “The purpose of the act being to prevent, and not to promote, fraud and mistake, we do not feel inclined, even in a doubtful case, to grant registration to a claimant where it appeared, as here, that when he adopted the mark he knew of its prior adoption and use by another firm in connection with goods of the same general character and properties. The opportunity for selection being as limitless as the hpman imagination, we have reason to question the motive prompting "the. adoption, by one dealer, of a mark previously applied by another dealer to like good.”

The case here presents no great difficulty. Appellee is using the mark in question upon an appliance which belongs to a class in use by -appellant. The general system of appellee, to which the appliance belongs, possesses the same descriptive properties of the system which bears the mark of appellant. That such a condition would in all probability lead to confusion in trade is evident. A situation therefore exists which is forbidden by the statute.

Inasmuch as the objection to the use of the distinguishing part of appellant’s corporate name was .not set out in the notice of opposition, it must be deemed to have been waived. See opinion of this court in Rookwood Pottery Co. v. A. Wilhelm Co. ante, 1, filed this date.

The decision of the Commissioner of Patents is reversed, and the clerk is directed to certify these proceedings as by law required. Reversed.