[Washington correspondence of theNew York HeraUO The patent lobby is gradually coming in the field this session, though, so far, the india rubber interest has kept rather out of the way. Sam Colt, the pistol man, has rented a house here, and made application for a revival of his expired patent. His prospects in that connection are not brilliant; for whilst many members do not object to voting for the extension of an existing patent where a plausible cause can be shown, there are several of them who regard the revival of an expired patent as a different matter. They consider that when a patent has expired, the right to it becomes vested in the public, and that Congress has no constitutional right to deprive the public of this acquired right. But in Colt's case it is hard to understand what solid pretence he can set up for a revival of his monopoly. As he was a poor man when he commenced, is now wealthy, and has made all his money out of his patent, he cannot seriously pretend that he has not had that reasonable reward for his invention which is all the principle which the patent law contemplates. Tho shorter the time a pateut monopoly exists, consistent with a due reward for the inventor, the better for the public and the progress of inventions. To extend them for an unreasonable period, is to stop, during that time, all'improvements in the particular article, except what the original inventor chooses to adopt. Col. Colt has made good contracts with the English, French, Russian and American governments, and he is scarcely an object for the eleemosynary regard of Congress. McCormick, the reaper patentee, is also here, trying to get, not an extension of his present patent, but a revival of the first patent he took out, for a crude machine which he never made work. He improved on this crude principle, and has a patent for his improv-ment. But what he seeks is a revival of the patent on his first crudity, so as to prevent any other person from making improvements on it, as it might interfere with his present monopoly. He has plenty of money to prosecute his matter, but so far he has had but meager success, either at the Patent Office or in Congress. He has been trying to get a bill passed for several years, and is here again to resume his labors. The india rubber interest consists of the Chaffee patent, the Hayward patent, Horace F. Day's claims, and the Goodyear patent. The Chaffee and the Hayward patents have expired, and their renewal is sought. They are both for preliminary processes in the manufacture of the vulcanized rubber, and either of them, if revived, would control the Goodyear patent. The Goodyear patent expires next June, and the Commissioner of Patents will then decide whether he will extend it for six years or not. This interest is one of the wealthiest in the country ; and the profits, if either Hayward's patent or Goodyear's is extended, are computed as high as fifty million dollars. There was a large lobby here last year in the india rubber interest, and I see some of the managers again on the ground.