C. I H., ol R. L—The experiment has been tried of putting one wheel IOOBC on the axle of a railroad car to oTercome the friction on the curveB. We have never heard of any special objection to this method, although we understand tbat arrangements a analogous in their operation are liable to throw the cars from the track. I E. a, of Md.—If a patent baa baen secured in the United States for an invention for an old device that had been long before used in a foreign country, upon such being brought forward on trial, the court would diBmiss the case, and the patent would be useless. I. F. H., of Me.—We know nothing of the nature of Mr. Hudgin'a receipt, as he has not communicated thiB information to us. We cannot be presumed to know the character of all the articles advertised in our columns, although we mean to use all proper vigilance to protect our readers against imposition. Mr. Hudgin can be called upon, by those who propose to purchase his receipt, for vouchers as to his standing and character. L. W., of Ct—You are no doubt correct in your ideas in regard to the sun-dial and needle. The combination is very old. J. M., of R. I.—We thank you,f or your kind allusion to our Patent Agency in your case. We always do the best we can for our clients—and it is quite certain that if we cannot succeed, there is not much chance efoje-where. A. S., of Conn.—Good ink will never become mouldy, but we should advise you to add a few crystals of copperas to yours, as there iB evidently too much gall. W. B. S, otB.—You can only relieve your salt well of gas by digging a supplemental well some distance from the other, and tunnel between them, so that the brine baa flow into the supplemental well from which it can bi pumped, and the gas can escape from the brine well. The supplemental well need only be a few feet in depth below the surface of the brine. Frederick Kesler, of Great Salt Lake City. Utah, wishes to correspond with Borne party who can furnish the best wheat waaher and dryer, a machine capable of washing and drying the wheat in a very Bhort time ready for the stones. P. P., of Mass.—We are Borry that you have been deceived in referenee to the man who advertised, in our columns, to re-point gold pens. You say that you " had no thought of making UB a party to the humbug, aB you have for years been in the habit ofaB-sociating with UB a peculiar reliability." This iB very complimeutary, certainly. Ever since we became connected with this paper we have labored industriously to make it in every war reliable, but we cannot alwayB determine tho character of our advertiser!, atflRmgta we can uBually decide on the propriety of publishing matter which they wish inserted. Plaster of PariB mixed with water iB tlio substance generally used to affix the common metallic topB to the glass lamps, H. A., of Ala.—You can make an approximation to the amount of alcohol in wine with an hydrometer, but the only accurate way iB by distillation. Home made wines generallyrequire some spirit, such as brandy, to be added, to keep them for any length of time. T. F. of N. Y.—If you attached a Bliding horizontal arm to a vertical rod, and desired to force the arm down by means of a weight, you would place the weight on the arm close to the vertical rod, and not at its extreme end; for the latter position would cause the arm to hug the rod, and thuB retard its descent. The exercise of a little reflection will enable you to Bee this. We have no doubt that impure water iB oftqna cause of fevers and other diseases, and that it is a good plan to purify it by sinking a barrel filled with charcoal and perforated with holes, so as to permit the disenfectant to ,ct upon the water. This has often been done, though, perhaps, not in the saine way. We were not aware, before you mentioned it, that a barrel of charcoal would answer thia purpose for two years. We did not say that lightning never went from the earth to the cloudB; we said M seldom.'1 It iB afeill a- matter of opinion whether or not it is a common occuence as you seem to think it is. W. R. W. of Boston, H. O. A. of N. O.—We thank you for your complimentary allusionB to the vigilance of the SCIENTIFIC AMKEICAN PATENT AQKNOY, aa shown in your case. We are successful in getting patentB for many meritorious inventors, after their caseB have been rejected throngh mismanagement by other hands. Inventors who employ our agency can always depend upon fair, candid and earnest attention. A. T. M. of. N. Y—We are not aware of a second edition of " Piesse's Art of Perfumery." The article noticed by you in the SOIENTIFIO AHKBICAIT, from the pen of Mr. Piesso, are sent directly to us bv the author. We are glad to bear that our paper is so well liked among your people, and hope the number of admirers will increase on the new volume. If all our friendB would only lend us a little of their time, we should have a larger list than at present. Money received at the Scientific American Office on account of Patent Office business, for the week ending Saturday, August 21,1888 :— W. H. G.ofWis., $45; P. S. C, of 111., $25; E. S., of Texas, $65; G. M., of N. Y., $30 ; L. R T., of Conn., $32 ; B. S. M., of Iowa, $25; S. M., of N. Y., $35 ; W. R. C, oflow.i. -ISO ; W. H, of N. Y., $30; A. C, of N. Y.,.?31; C. N. S, of Conn.. $30; a C. H., ofN.' Y.,$55; J. L. R.'of N. Y. $30; M.&B.,of N. Y, $30; W.S. W.,of N. Y.,$20; A. S., of Pa., $25; W. II. T., of Mass., $35; A. C. B , of Mo., $80 ; J. A, Jr., of Mass, $25; M. K, of N. Y., $30; F. &, of N. Y., $40; S. a T., of Ind., Sfi-'B; P. W. G., of HI., $S0; J. R of Mass., $25; J. A. R, of Fla., $34; L. & % of N. \Y., $80; J. W. C, of Ind., $25; M. & McL'ofGa., $60; G. R C, of N. Y.. $30 ; T. S. E., of Ind., $15; J. C. M., of Mich., $30; H. N. B., of N.Y\, $20; C. B. C, of K. I., $65; A. P., of Mass, $30 ; J. C. A., of Ohio, $25; P. P. J., of Pa., $30, J. B,of 111, $25; H. S, of N. Y, $30; J. R, Jr., Mass, $30; J. & R. McM., of N. Y., $80. Specifications and dm wings belonging to parties with the following initials have been forwarded to the Patent Office during the week ending Saturday, August 21,1858:— P. S. C, of HI.; A, F. T., of Mam ; M. K,of N, Y.: J. C. A., of Ohio : O. L. C, of IU.; A. S., of Pa.; J. R, of 111.; J. A. B., of Fla. (2 cases); J. W. O,,of Ohio; A. D. B., of N. Y. ; J. R, of Mass. ; E. C, of N. Y.; S. S. T, of Ind.; M. & W, of Ind.: J. A. Jr., of Mass. ; W. H. T., of Mass.; C. C, of Miss. Literary Notices THB EOMOTIO MAGAZINE.—W. H. Bidwell, Editor, 5 Beekman staeet, New York.—The August number of this interesting periodical is full of well selected articles, carrying the reader's mind through the sciences of space, landing him in the field of romance, in the 144 pages which compose a single number. " Lieut. Malir/s Geography of the Sea," "From Delhi to Oawnpore," and "The Romance of History," are, in our estimation, the best articles. THE ECLECTIC MEDICAL JOUBNAL__R. S. Newton, M. D, Cincinnati.—We do not especially believe in eclecticism as a system of medicine, but we do believe in thia journal, lor in it every subject that its contributors handle is treated in a plain, practical, common-sense way.