"Whenever the owner of a musical copyright has used or permitted the use of the copyrighted work upon the parts of musical instruments serving to reproduce mechanically the musical work, then in case of infringement of such copyright by the unauthorized manufacture, use, or sale of interchangeable parts, such as disks, rolls, bands, or cylinders for use in mechanical music-producing machines adapted to reproduce the copyrighted music, no criminal action shall be brought, but in a civil action an injunction may be granted upon such terms as the court may impose, and the plaintiff shall be entitled to recover in lieu of profits and damages a royalty as provided in section one, subsection (e), of this Act: _Provided also_, That whenever any person, in the absence of a license agreement, intends to use a copyrighted musical composition upon the parts of instruments serving to reproduce mechanically the musical work, relying upon the compulsory license provision of this Act, he shall serve notice of such intention, by registered mail, upon the copyright proprietor at his last address disclosed by the records of the copyright office, sending to the copyright office a duplicate of such notice; and in case of his failure so to do the court may, in its discretion, in addition to sums hereinabove mentioned, award the complainant a further sum, not to exceed three times the amount provided by section one, subsection (e), by way of damages, and not as a penalty, and also a temporary injunction until the full award is paid." {Sidenote: Copyright Office form and fees} The Copyright Office provides a special form (U) on a blue card for registration of "notice of use on mechanical instruments," in which the copyright owner of a musical composition gives notice that he "has used or has licensed the use of said composition for the manufacture of parts of instruments serving to reproduce mechanically such musical work." The recording fee for such notice, as fixed by the statute (sec. 61), is twenty-five cents for the first fifty words and twenty-five cents additional for each additional hundred words. For recording and certifying the license referred to (sec. 1, e) the statute provides (sec. 61) for a fee of one dollar for not over three hundred words, two dollars if not over one thousand words and one dollar for each additional one thousand words or fraction thereof over three hundred words. {Sidenote: The constitutional question}