Messrs. Editors—I noticed some weeks since an announcement in the Scientific American that Charles Goodyear had applied for an extension of his india-rubber patent, and that the time for hearing had been fixed for some day during this month. I am interested in the result of this case, and have been anxiously watching f or an expression of your opinion in reference to it, but not one word have you uttered for or against it up to this time. It was in your power to have defeated Goodyear's case if you had taken hold of it in earnest. I now fear it is too late. Why have you permitted this single important case of extension to progress without opposition ? I cannot understand your silence. H. New York, June 9, 1858. [Our correspondent refers to the patent of Goodyear, issued on June IStb-, 1844, for the principle feature in vulcanizing india-rubber. It embraces the "curing process," which consists in submitting prepared rubber to a high degree-of heat, which preserves it from being affected afterwards by atmospheric and other influences, and yet sustains its elastic character. It is a very valuable patent; the process is essential to all the varied manufactures oi this material. From the tone and language of our correspondent's letter, it is evident that he does not understand our position in regard to the extension of patents. In commenting upon his communication, we wish him (and all others who may hold similar views and opinions) to note particularly that there is a radical distinction in nature and in charactei between the extension of patents by the Commissioner, according to an established general law, and the extension of patents by special acts of Congress ; this case of Goodyear comes under the former classification. Our opinions in regard to all such questions are guided by general principles,* and have no reference whatever to persons (Jr parties whose interests are likely to be affected by them. By a general law of twenty-two years standing—section 18, Patent Act 1836—t patentee may have his patent extended foi seven years from the expiration of his first term, provided his invention is a useful one. and he has not been sufficiently remunerated for its use. To obtain an extension, he is required to show proof of the value of his invention, and the amount of remuneration he has received for its use ; and all those opposec to the extension are notified to appear, anc show cause why it should not be granted. Ii such cases a fair hearing of both sides—those for, and those against the petition—is obtain-ed, and the Commissioner of Patents, upoi the testimony before him, adjudicates in the matter. As good citizens and just journalists we could not, therefore, consistently oppDS the extension of Goodyear's patent, or an^ other person's patent, so long as the application is confined to a general law enacted t( meet all such cases. To do so would be t( act the part of obstructionists to the fulfilmen of the law ; and it would also be passing judgment without a requisite knowledge of all th facts of the case. We consider that th( Commissioner of Patents is the most competent person to pronounce judgment in sucl cases. He is sacredly obligated to dispense justice and maintain the law ; and as he hai all the evidence of both sides before him he ii certainly the best judge as to the right an( wrong of granting or refusing such exten sions. These brief remarks are smfficientlj explanatory, and will, no doubt, be satisfac^ tory to all who read them, in regard to ou: position of silence in cases coming up befor the Commissioner of Patents for extension, ac cording to an established law. We have opposed the extension of patent by Congress upon general principles; and a we entered very freely into the reasons for s doing in the article on page 277, we will noT add but a few words pertinent to this question Most of those patents sought to be extende( by Congress have already had the benefit o a seven years' extension, or their owners have been well remunerated, and have been refused an extension upon a fair hearing before the Commissioner of Patents. Every bill enacted by Congress for the extension of a patent, is a new law, in every sense of the term, because it is a special act provided for a private person, and cannot be advocated on general^rln-ciples. To extend patents by acts of Congress to favored individuals is contrary to the spirit of our government; it involves class legislation, and creates invidious distinctions. All patentees,are entitled to stand upon the same level in th& eye of the law the rights of one are as sacred as those of another. Our course of conduct in regard to these questions is governed by motives which appear to us to be just, fair, and honorable. We have no personal feelings to gratify, and no private interests tQ subserve, in opposing the extension^ of patents by Congress on the one hand, or in remaining silent in regard to those that come before the Commissioner, on the other.