DALLAS, Circuit Judge.
This is a motion for a preliminary injunction in a patent cause. The only legitimate purpose of such an ' injunction is to preserve the existing state of things until the rights of the parties can be thoroughly investigated and disposed of upon final hearing, and any unnecessary expression of the views of the court should, in the meantime, be avoided. The complainant is, in my opinion, entitled to the order he asks, upon facts which the proqfs, as now presented, clearly establish; and therefore no others'will be discussed. The letters and the bill, of the defendants Hawthorne and Sheble to the Allen Phonograph Company show a sale by the former to the latter of a machine which cannot be used for any purpose except to make duplicates of sound records described and claimed in the patent in suit; and the validity of the patent, and that the unlicensed making of such sound records would violate it, being conceded, there is no room for question that this sale of a machine, which it is admitted by the affidavits of Hawthorne and of Sheble was a duplicator, constituted an infringement. Their letters plainly show *517ilial they perfectly well understood that the purchaser intended to use it for making sound records; and, this being so, the statement in. Hawthorne's affidavit that his iirm did not make it, and did not themselves make any records upon it, is wholly immaterial. Where a person sells a machine which is useful only for the purpose of making a patented article, of makes such sale with knowledge that the thing sold is to be used to produce an infringing article, the seller is himself liable as an infringer. Walk. Pat. (3d Ed.) § 407. Careful comidera!ion of the affidavils has also fully satisfied me that the defendants Knediker and Carr have made for their co-defendants Hawthorne and Hheble phonographs, or at least parts thereof, with knowledge; that they were to be used, or to be put together for use, as, duplicators to make sound records. Without the affidavit of James P. J»radt, tire proof of this fact would, I think, be complete, and that affidavit piares it beyond possibility of question. It is to the effect that Mr. Cnediker admitted that his Ann had made parts of such machines for Hawthorne and Slu-ble. and that he understood that they were parts of phonographs. This is a distinct statement of fact, which, if false, could, with equal distinctness, have readily been denied: but no denial of it has been made. In considering this motion I have regained with solicitude the familiar principle that a preliminary in junction should be awarded with extreme caution, and never where the right is doubtful or the wrong uncertain; but here the right is admitted, and of its invasion there can be no reasonable doubt. The complainant’s motion for a preliminary injunction is granted.