J. H., of Me.—You will not invalidate your claims to a patent by introducing your invention now. We have enrolled your name upon our subscription listt H. M., of Ind.—Such engravings of your invention as will anflwer our purpose to publish in the Scientific American, will cost you $10 We can get up suitable engravings for handbills, etc, for $6. A. W. F. F,, of Va.—One pound of coke will evaporate 12 lbs. of water, bat only 9 lbs. of water are evaporated in a locomotive boiler. It is surely possible to get a better per centage from the fuel. H. 0. B., of Ind.—Dalton has evaporated 10 lbs. of water by one of charcoal; 12 lbs, of water can be evaporated by one of coke ; he tested the quality of different kinds of fuel. J. F. H., of E. 0.—Your shoulder brace is very good; the yellow coloring property of the Barbaiy bark has been long known. Be careful in your experiments with potassium and sodium ; amorphous phosphorus is the best thing yet discovered for' making the matches. j E. W. S , of Pa.—Your plan for increasing the draught of steamboats will answer very well, it is the same as that used for locomotives, except yours has an adjustable mouth, which so far as we know is patentable as you apply it. R. M., of D. C—Yours will receive attention next week. A F. W., of Pa—We cannot refer you to any work for working drawings of paper machinery as used at present in the manufacture. The Cornish double beat is excellent. B. F. R., of Pa.—You will not get half the power of your water from a Barker's mill; get are-action wheel. The Barker mill, however, may do all your work, and you perhaps can build it yourself; if you knew the quantity of water discharged we could tell the power, not otherwise. M. K., of N. Y.—Prof. Page's engine has been patented in Europe, but not here ; a battery has but one negative and one positive pole, your idea about three we cannot understand. The bar can certainly be divided into three separate parts j but you cannot get them to work as you propose; they will all move together in one direction. 0. S , of Mass.—There is always danger of life from lightning passing into telegraph offices, if the conductors are not sufficient to carry off the discharge to the ground. We have not received minute information about the telegraph office at Buffalo' Some telegraph instruments have been destroyed. It is possible for operators to be vigilant at all times. Your suggested improvement can be easily tried, and you should do so. S. D., of Ct.—No patent could be secured for a clothes pin made as represented in your sketch. A. C.C., of Ky.—Your letter, containing $3 for expense on model, is recelvBtn "" J. W. M., of N. H.—We have carefully examined the sketch of your alleged improvement in ship's rudders ; it contains nothing new or patentable. 0. L' J., of Ohio—It is impossible for us to form an opinion respecting the novelty of your invention without a sketch and proper description of it. You could easily construct and send us a model which we advise you to do. M. C, of Cincinnati—We shall examine your communication of the 18th, and will write you soon. W. W., of Pa.—We certainly think there is no doubt about your getting a patent, but what could you do with it. It has reference to no interest in this country, therefore a patent would be valueless. Money received on account of Patent Office business for the week ending Saturday, May 31:— B. W.,of Ct., $30; F. 0. W., of N. Y., $300; S. McK.,of N.Y.,$55; J.C., of N. Y,, $27; W. 0. M., of N. Y., $30; J. E. A., of N. Y., $15; A. D. 0., of N.T., $30;D.McM.,of -----, $10 jO. B.5 of Mass., $30 ; I, Z. A. W., of Pa., $100 ; T. R,, of N. Y., $40 ; H. C, of N. Y., $30 ; W. S., of N. Y., $45 ; S. K., of N. Y., $67 ; J. G., Jr., of N. Y., $84 ; W. C, of 0a, $21. Specifications and drawings belonging to parties with the following initials have been forwarded to the Patent Office during the week ending Saturday May 21 :— M. B. F,, of ST. Y.; M. S , of N. Y.; 1. C, of N. Y. ; J. R., of Mich.; M. T., of N. H. ; A. C. K., of N. Y. (2 cases.) .