It is well known to our readers what ground we have taken in respect to the principles of patents, and how we have endeavored to set so many legal gentlemen right in respect to the nature of inventions. It has always appeared to us that many of our judges and men of legal fame have had very confused ideas of what a principle is. The decision made by Judge Kane, on which we freely commented on page 67, Vol. 7, Scientific American, and the letter of th Hon. A. Kendall, page 170, this volume, present examples of what we call "confused ideas and incorrect views respecting an art and a principle, as connected with patents and inventions." We have now before us a certified copy of a decision of the U. S. Supreme Court, made at the last December term, and which was referred to in Mr. Kendall's letter, which is in exact accordance with the doctrines we have taught, and the views set forth by us from time to time respecting the principles ol patents. The case is one of error—an appeal taken from the Court of the Southern District of New York, in the case of a patent for manufacturing lead pipe. In 1837, John and Charles Hanson, of England, obtained a patent for an alleged improvement in the manufacture of lead pipe, and in 1841 a patent for the same was taken out in the United States, which was assigned to Messrs. H. B. B. Tatham, and afterwards G. N. Tatham was admitted a partner. A re-issue of this patent was granted in 1846, and a suit was commenced in New York against Thomas Otis Le Roy and David Smith for infringement ol the same, and damages of $20,000 claimed. The defendants pleaded not guilty and asserted that the invention was not new, that the machinery had been described before and was not patentable. The Court in charging the jury in the Case said:—" There can be no doubt if the combination ot the machinery claimed is new, and produces a new and useful result, it is the proper subject of a patent, the result is a new manufacture. And even if the mere, combination of the machinery in the abstract) is not new, still if used and applied in connection with the practical development of a principle newly discovered producing a new and useful result, the subject is patentable." [We request the attention of Mr. Kendall to these sentiments] "In this view the improvement of the plaintiffs is the application of a combination of machinery to a new end, to the development and application of a new principle resulting in a new and useful manufacture. In the view taken by the court in the construction of the patent, it was not material whether the mere combination of machinery presented by the defendants as having been described before was similar to the combination of the Hansons, b ecause the originality did not consist in the novelty ot the machinery, but in bringing a newly discovered principle into practical application by which a useful article of manufacture is produced." To these charges of the court the defendants took exceptions, and carried the case to the U. S. Supreme Court. Judge McLean delivered the opinion of the Court, to which we request the attention of our readers interested in patents, so as to take particular notice of the opinion of the U. S. Supreme Court, and see how it accords with the views we have always expressed in respect to patent principles. The court said :— "The word Principle is used by elementary writers on patent subjects, and sometimes in adjudications of Courts with such a want of precision in its application as to mislead. It is admitted that a principle is not patentable. A principle in the abstract is a fundamental truth, an original cause, a motive; these cannot be patented, as no one can claim in either of them an exclusive right. Nor can an exclusive right exist to a new power should one be discovered in addition to those already known. Through the agency of machinery a new steam power may be said to have been generated, but no one can appropriate this power exclusively to himself under the patent laws. The same may be said of electricity, and of any other power in nature, which is alike open to all and may be applied to useful purposes by the use of machinery. In all such cases the processes used to extract, modify, and concentrate natural agencies constitute the in- . vention. The elements of the power exist, the invention's not in discovering them, but in applying them to the useful objects.— Whether the machinery used be novel or consist of a new combination of parts known, the right ,pf the inventor is secured against all who use the same mechanical power or one that shall be substantially the same. A patent is not good for an effect or the result of a certain process, as that would prohibit all other persons Irom making the same thing by any means whatever. This, by creating monopolies, would discourage arts and manufactures against the avowed policy of the patent laws. A new property discovered in matter, when practically applied in the construction of a useful article of commerce or manufacture is patentable, but the process through which the new property is developed and applied must be stated with such precision as to enable an ordinary mechanic to construct and apply the necessary process. This is required by the patent laws of England and of the United States, in order that when the patent shall run out the public may know how to profit by the invention." [Let our readers examine page 67, Vol. 7, Scientific American, and pages 170, and 214, present Vol. Scientific American, and compare the above with our views therein expressed.] " In the case before us the court instructed the jury that the invention did not consist in the novelty of the machinery but in bringing a newly discovered principle into practical application, by which a useful article of manufacture is produced, and wrought pipe made as distinguished from cast pipe." A patent for leaden pipes would not be good, as it would be for an effect, and would consequently prohibit all other persons from using the same article however manufactured." We request the attention of Mr. Kendall to the last paragraph, the decision is just such as that which his letter states the " court did not imake." The instructions of the New York Circuit Court were totally at variance also with the claims of the patent, for the claim is as follows:—"The combination of the core, bridge, or guide piece, the chamber and the die when used to form pipes of metal under heat and pressure in the manner set forth," and respecting this the U. S. Supreme Court decision says :—" The combination of the machinery is claimed through which the new property of lead was developed as the part of the process in the structure of the pipes. But the jury were instructed " that the originality of the invention did not consist in the novelty of the machinery, but in bringing a newly discovered principle into practical application. The patentees claimed the combination of the machinery as their invention in part, and no such claim can be sustained without establishing its novelty ; a newly developed property of lead was not in the case." The instruction of the Circuit Court, New York, was ruled to be wrong, and the judgement reversed. We would state that the opinion of the U. S. Supreme Court, as set forth above, accords with that of the most eminent jurists in patent laws, and the instructions of the court of New York in this case, and the decision of the court in Philadelphia in the Morse and Bain case, excited great surprise in us. " Is it possible," we said,"that we have any judges so defective in knowledge respecting patent laws." Mr. Justice Buller, as quoted by Webster, says in reference to the question of patent principles. "The method and .mode of doing a thing are the same, and I think it impossible to support a patent for a method without carrying it into effect and produce some new substance. But here it is necessary to inquire what is meant by a principle reduced to practice. It can only mean a practice founded on a principle." A line of propellers has been started to carry Cumberland coal from Baltimore to New York. A Mechanics' Institute is about to be established in Louisville, Ky.