0., of N. J—We have given our opinion on the same subject in a recent number of the Scientific American. S. C, of Texas—We have seen a rotary wheel driven by electricity of nearly the same features as yours, and which was applicable to the propulsion of vessels, but it is not a practicable engine, in comparison with steam. We advise you not to go into any expense in making an engine. T. J. C, of Ohio—There is no machine in use for the purposes stated, viz , engineering and surveying. A number of instruments are used. C, F., of N. Y—Your's just came to hand while about ready for the press. H. H., of Va- You will see a notice of Ericsson's engine in another column. Your plan is not like his, but we must know more about it before we can say whether it is or is not patentable. W. D, E., of Miss—We have seen models of such plows as you mention, and presume they are in use in some sections. If you wish your's examined, please to send a model or sketch and description. L. B. F., of Mass—The principle of your invention is substantially the same as Paine's Patent, and no patent can be obtained for it. The mode you have adopted for securing the window is not the same as Paine's, but yours possesses no advantages over his, and so long as the ventilating principle is the same, we cannot advise you to make an application. The amount sent for subscriptions has been employed for that purpose. H. S. W., of Ohio. -There is nothing new or useful in your alleged improvement in the steam engine Your's and kindred devices have been known and have passed out of use. J. W. A. R. M., of Canada—It is utterly out of the question for us to think of republishing our first volumes. Many of the engravings are not in our possession, and it would require much time and labor to do justice to the work, more time than we could appropriate outside of our ordinary duties. E. B , of N. Y—Your arrangement is slightly different from anything we have ever before seen, and we think it involves a limited amount of novelty- M. & E., of N.Y—Your model was received with ten dollars on the 10th inst. We will proceed with your business in its turn, which will be about ten days hence. G. W.5 2nd, of 0 —One dollar received. All right. J. J. J., of Pa—Your's will receive attention The question had nothing to do with momentum, merely the revolution, as we stated, if the small wheel slides over its surface in every revolution, how much will it slide to make it describe a line as long as the large wheels. A. J. of Ohio—Gun barrels are browned by mixing up some nitric acid and water, and dissolving some copperas in it, and then apply it to the gun barrel with a cloth, merely moistening it, and then let it stand two days, when it will be coated with rust, brush this off with a wire brush, and do the same work over again, after which wash with warm water, then oil it and finish. The acid solution must be weak. Razors are etched by covering them with a varnish of beeswax and pitch, then removing the parts which you wish to etch, with an instrument, and biting in the metal with a weak acid, such as nitric mixed with water. W. M, M., of 111—In a short time we will publish a series of articles on Artesian Wells. They are all supplied by rains, and this is what the Scriptures mean when they say, " the hills are watered from his chambers,"—chambers of heaven. When rains cease, springs cease to flow. H. Van D., of N. Y—We think it will be extremely difficult for you to get a patent for a mode of closing the buckets so as to give them any degree of aperture, it is described in Haviland & Tuttle's specification. S. & K., of-—We have taken some pains to examine your letter, and have searched for information so that we might be able to give you a3 correct an answer as possible; we believe your plan is patent table; so far as we have been able to judge, it is a new and useful invention. It is our opinion that very few pockets are picked in ourcities except in large crowds. W. F. S., of Ala—You may employ a plate of copper and zinc, alternately, with a division between each pair, and amalgamate the zinc plates with quicksilver. Use a solution of the sulphate of soda in the battery. There is no patent on this battery, nor on any of those in common use. A. M, of N H—Steel is a combination of iron and carbon in certain proportions. A. .R., of Ala—The art of stereotype printing Is the invention of Lord Stanhope. R. F., of G&—The carpets from England, called Kidderminster, derived their name from being originally made at that place, but they are now mostly made in Kilmarnock, in Scotland. A. M. N., of Me—The Toledo swords are celebrated for the excellence of the steel. -—, Bangor, Me—Our correspondent at this place, who inquires about Wood's Pump, fails to sign his name to his letter, therefore we are unable to reply by letter. We can find no such patent; perhaps you had better write to the Commissioner o Patents ; he would answer your inquiries under the circumstances. P. B, S., of Baltimore—Your invention is quite a different thing from what we supposed it to be from 3 your former description. It is not, in our judgment, k practioable, and we advise you to abandon it. Money received on account of Patent Office bnsi- less for the week ending Saturday, Nov. 13:— H. R., of-, $25 : W. T., of N. Y., $40 : M. R f Me., $35 ; J. M., of Pa., $55 ; E P. R., of N. Y., 6350 ; A. H. & Co., of Pa., $222; M. & E , of N. Y., 640; C. W., of N. Y., $10; L. N. L., of Mass., $20 ; a. M. & Co , of Mass., $30 ; T. A., of N. Y., $20 ; H. 3 , of N. Y., $20 ; R. & S., of N. J., $25 ; A. W., of n , $30 ; J. R. K., of Ga , $50 ; H. G., Jr., of N. Y., 25; J. Gt. P., of R I $20 ; S. J. P , of Ct., $55 ; W. B. H , of N. Y., $20 ; S. & D., of N. H,, $30. Specifications and drawings belonging to parties vith the following initials have been forwarded to Jhe Patent Ofiice during the week ending Saturday, Jov. 13: S J. P,, of Ot.; C & K., of Pa.; J. M., of Pa.; L. J. L , of Mass.; H. G., Jr., of N. Y.; E. N. B., of L. [.; S. & D., of N. H.