L. Q-., of N. Y mdash; We think favorable of your im proved method of preventing car axles from break-, ing, but may change our views after examining a sketch and description which you had better send us. W. M. L., of La.mdash;We have ordered the machine you want, but shall not be able to obtain it until about four weeks ; the delay is unavoidable on our part. 4 M. M, of La.mdash;We think favorable of your ideas in regard to boxwood, but there is no chance for a patent. W. W., of L. I.mdash;No patent could be obtained for the article you mention, and we advise you not to make an attempt. S. C. H., of Ohio.mdash;You ask if a single engine with a fly-wheel, will give as steady a motion to stones as a double engine with the cranks set at right angles. If the engine is worked up to its limit of power it will not. It has been found that for milling purposes it is difficult tofget a steady motion from steam power. The engine or engines must be powerful and there must be plenty of steam so as to allow them to work easy. You state that two thirty feet boilers of three feet diameter do not drive any more than two run of stone. Have you fire bridges under themmdash;do you burn coal or wood ? Boilers that use coal should never be more than six times the length of their diameter. In every case we advise the employment of tubular boilers, and the use of pure water in them. There should be nine square feet of heating surface for each horse power; by making your calculations you can determine whether your boilers are correct or not. D. B., of N. J.mdash;You may rest assured that lime will never supersede coal j a pound of coal will convert far more water into steam than a pound of lime, this is the test. E. L. N., of Mass.mdash;Guess you have discovered the article by this time without the aid of those spectacles. E. S) of Me.mdash;We are the agents of Mr. Avery for procuring his foreign patents, and think we know what we are about when we pronounce it a first-rate machine for the price. J. M. B, of Del.mdash;We have shipped several concentric Lathes to Philadelphia, but the names of the parties who purchased we have entirely forgotten. J, T , of Phila.mdash;The "Mechanic" we referred to died three or four years ago. S. S., of N. Y.mdash;If fire understand your drawing, we believe your invention to be patentable ; the claim you suggest would have to be greatly modified however. J. Y., of Ohiomdash;The error you speak of was corrected before the papers were sent to the latent Office. An engraving of your invention would cost $10. G. W. H., of N. Y.-We fail to discover any thing patentable in your Match Safe, although they are a very pretty article of manufacture. D. R., of N, C.mdash;Your subscription will expire at No. 26, Vol. 9. It was a mistake of ours in receiving tha price of binding twice, H. Van de W., of N. Y,- Your wheel so closeyre-aemTtfte the one illustrated in the 14th number, present volume Sei. Am., that it would not afford sufficient interest to our readers to warrant our publishing an engraving f it. R, S., of 111.mdash;We have duly examined the sketch of your alleged improvement in Rotary Engines, and recognize in it an old acquaintance: we have been familiar with the same plan for someyears ; sae Vol. 4, Sei. Am. I. H. G-, of Iowamdash;We did not answer your inquiry because we were unable to do no. The firstques-tion is a " poser," and we know what you mean but know of no one who can approximate to anything like a true estimate ; we think there is no machine which does the work you spsak of. H. G. R., of Tenn.mdash;We have examined the sketch of your alleged improvement in Churns, and cannot discover anything new or patentable in it ; we have seen the same plan before. F. V. D., of Mich.mdash;Machines to be operated by the action and re-action of waves is well known andhave been variously modified ; you may have some new contrivance, but it is doubtful. G. R- Selkirk, of Michigan City, Ind., wishes to purchase a suit of Submarine Armor of the most approved construction. J. F. J., of N. Cmdash;We have handed over your letter to an engine builder. S. F H,, of Bostonmdash;You can send us a full and complete description of your Car Seat for examination. H. R., of N. H.mdash;We never publish engravings entirely devoid of letters of reference to enable us to explain the operation of the invention R. L. O, of Pa.mdash;We do not see the advantages you claim for the device mentioned in your former letter ; you might make an experiment and fully satisfy yourself. G. 0., of N. Y.mdash;It is no easy matter to arrive at your meaning from the brief description and sketches you have presented. The idea presented ia that of a double tier of buckets on the wheel, the upper the percussion, the lower the re action; this form of wheel is not new, and so far as percussion and reaction is concerned the application is an anomaly. C. L., of Ct.mdash;You may perhaps have seen accounts of thus allowing the exhaust to escape into a cold water tank ; we have so used it ourselves ; but jhe extract showed how far they were behind in Europe ; i* is the same with the gas patent ; it will nevr benefit the patentees where coal can be pur. chased. E. A. W., of N. Y.mdash;Mason and Dixon's Line acquired its name from the surveyors. Any work on Natural Philosophy will give you the information about the atmosphere ; the answer would be too Long for us to give. W. R. R , of N. Y.mdash;The hollow shaft, for the weight of metal, is the strongest, but certainly a so-Lid cast-iron haft is as stroug as a hollaw one of the ame diameter. J. C, of N. J.mdash;Brass is the best metal that weare acquainted with for counters for store advertisements. Money received on account of Patent Office business for the week ending Saturday, Jan. 8 : G. D , of N. Y., $30 ; N. C. T., of N. Y:, $35 : J. E., of N. Y-, $25; J.C. S., of Pa., $30; H.L.F. G-, Df Mich., $25 ; E. B. W., of N. H.,$30; F. J. T., of N. Y-, $30 ; C. W. G., of N. Y., $10 : J.C, D., of Pa,, $30; D. W. K, of Va., $25; D. M-, of N. Y., 20; J. H., of N. T., $37. Specifications and drawings belonging to parties with the following initials have been forwarded to the Patent Office during the week ending Saturday, Jan. 8: J.E., of N.Y.; D.M., of N. Y. : 0. S., of R. I. ; W. F., of Pa. ; J. H., of N. Y.: N. C T., of N. Y.