In conversation with one of our oldest and most distinguished American inventors, a few days since, he, by a few brief remarks, forcibly directed our attention to the great difference between the present and past times, in relation to the value of patents. About forty years ago, he obtained a patent for a very useful and valuable invention ; but this, instead of advancing his interests and establishing his reputation, seemed to produce quite the opposite results. On account of his having secured the invention by a "patent," he was regarded with suspicion, there existing, at that time, a strong prejudice in the community against all" patentees. This he found to operate so injuriously against him, that when he was—from the force of circumstances —compelled to offer his patent for sale, (which he thinks would easily have brought $300,000 at the present day,) he found it difficult to obtain a purchaser for $3,000. The person that finally bought it was a very shrewd man, who esteemed its value, and afterwards reaped great advantages from it, as a manufacturer. Prior to the reign of James the First, in England, it was quite customary to grant monopolies for the manufacture and sale of certain articles, without the least reference to invention. These patents were exclusive grants, which oftentimes stopped old manufacturers from pursuing their established callings ; and they were frequently bestowed upon court favorites, or other individuals who had sufficient means, or other equally attractive peculiarities, to bribe the monarch or his ministers. For instance, one person or company got a patent for the manufacture of beer, another for hats, &c, thus monopolizing the trade in their lines of business. Such exclusive privileges were violations of the peoples' rights, and were, of course, generally detested. The practice of granting such privileges was abolished in the reign of the king referred to; and the law of patents, which recognized only inventors and introducers of new manufactures, was enacted. Prejudices, however, are not easily rooted out; and no doubt they reigned in the minds of many of our early settlers, long after the English practice of grantingunjust monopolies had been abolished. Some of our colonies, also, did many things to create and foster such prejudices. Under the mistaken but laudable desire to introduce new manufactures, various monopoly patent grants were made to persons who did nothing to deserve them; but this practice was swept away at the establishment of the Federal Union. The central government early enacted a patent law, on the basis of the English code, under which no one could secure a patent but for some new and useful invention. This law possessed none of the features of a monopoly, because no established right was taken away, or destroyed by it ; but it did not immediately eradicate the prejudices which had existed against patents, and those to whom they were granted. This is the reason why patents— many of them for most useful inventions— were, at one time, of so little value in our country. We mean to be understood that these patents, even in the limited extent of our manufacturing operations then, were depreciated below their real value, owing to the public prejudice which existed against them. These prejudices, we are happy to say, are nearly all abraded from the minds of the people ; and the respected old inventor to whom we have referred, in alluding to this, warmly remarked " inventors do, indeed, live in better times now." There is no property which is more valuable or respected than patents at the present time, or more justly deserving protection and favor. A new patent destroys no old right belonging [to a single individual; it is a certificate from the government, signed by officers appointed for that purpose, that the person to whom it is granted has discovered something useful which is not known to have been in existence previously. This is the principle upon which patents are granted under the existing laws. The inventor to whom we have referred, has, to use a common but 'trite expression, become "well to do in the world," and he deserves this, because he has enriched it by the treasure of his genius. As every new improvement adds something to the solid wealth of the community, it is a good thing for us that the rights of inventors are more respected, by the public, and their inventions better protected by our courts than formerly. The prejudices to which we have referred once found a place even in the United States Patent Office. At one time its policy seems to have been strenuously exerted to find arguments on which to refuse patents, when evidence, as well as duty, should have counseled a different course of conduct. Instead of assisting inventors by candidly examining their claims, and deciding upon them with a liberal spirit, as the law contemplates, their claims were examined with prejudice, and oftentimes rejected upon the most frivolous pretexts, comparisons and references. A different spirit now reigns in the national counsels, and more ample and equable provisions have been made for securing the rights of inventors. Although patentees live in better times now than then, we are confident that still better times are yet in store for them.