M. W., of Pa.—The $5 received from you will pay Mr. F.'s subscription on year and balance your account with us, A. F. R., of N. J.—Why not employ Watt's "steam jacket " at once ; your plan could not be patented. N. C, of Ohio—Yours will receive attention. J. S., of N. Y.—We have never seen a water gauge for steam boilers like the one you have described. It appears to be patentable. J. S., of Iowa—Your plan for making self-raising flour is different from that which is patented, and we think it is a good plan and patentable ; your other plan, so far as we are able to judge, is also patentable. R. F.F., of Boston—Your plan for heating cities and villages with hot air, is feasible ; it has been proposed to us a number of times. The pipes would have to be made of some non-conducting material G. J. H., of Ohio—Lead and Z'.nc have both been used for milk pans, but we advise you to use neither ; tin is the safest ; zinc is so easily oxydized that it does not last long, but the pure white oxyde of zinc is not, strictly speaking, poisonous. D. H., of Ct.—An endless chain of buckets, employed as a water-wheel, is an old device and could not be secured; several references can be given. See Ree's Cyclopedia, or Vol. 3, Sei. Am. A. C S., of N. Y.—We do not know about the boiler iron. G. H , of Va.—Your proposition to light lamps by electricity is not new. J. H.,of-.—We don't see that there is any loss by the stationary guides , if a man lifts 100 lbs. two feet high, with his feet on a fixed platform, he will , only lift it one foot high,, if his feet are placed on a ; movable platform, so there is no gain nor loss ; your ! plan is new to us, however. j G. B., of Wis.—Your application is a long distance j behind ; write to the Patent Office ; a reefing paddle wheel is not new ; we published one in Vo 1. 1 of our paper ; we could not give an opinion about the stuffing box. D. S., of Iowa—The oil of sun-flower, has been tested, to our knowledge, in painting ; it is not as good as linseed oil ; for machinery it is far inferior to sperm ; we do not know how it answers for illumination. P. Van S,, of N. Y.—Your views about the loco- , motive are correct in one sense ; the oscillating is caused by the cylinders being placed outside, and j the rapid repeated strokes of the pistons in con- j junction with the velocity of the wheels ; by the j description of your horse-power we cannot get a proper idea of its value. Simplicity in machinery is the grand desideratum. S. S., of N. Y.—T e have received your letter describing an improvement in tables ; it is carefully filed jimong our oanfideatial papers. j C. W. Cooke, Waterloo, N. Y.—We find by reference to your letter that it was written seven thous- ' and instead of seven hundred thousand pounds of wool ; quite a difference. . R , of Pa.—Your plan, for propelling machinery isabsurd and cannot be made to operate to any advantage whatever ; no patent could be obtained. A. S. P., of N. C.—Your subscription expires with No. 43 ; all the power you can obtain from your wheel, is just the measure of force derived from the velocity and weight of the water which you call leakage. C. M., of Md.—Yours could not appear this week. J. S. B. of Ohio—No. 25 of the Scientific American cannot be furnished. The sketches of your alleged improvement in the steam engine have been carefully examined. The arrangement is new so far as we know, and it is our opinion that a patent can be obtained, of this however there is no certainty, so much having already been done. You had better experiment with it, and if possible ascertain its value. C. R., of Vt.—We wish it distinctly understood that buying and selling or speculating in patents is strictly avoided in this office. W. M. L., of La.—Wilson's Sewing Machine has not been adapted to sewing leather, but for fine work, linen, and cotton, it excels, in our opinion, any other machine in use; Elias Howe's machine is adapted to sewing leather, his office is at 205 Broadway, N Y. M. C, of Va,—Patentees can always have good engravings of their inventions exeouted from the Letters Patent, by sending them to this office ; it is for the interest of every patentee to have his invention illustrated in a journal of wide circulation, devoted to mechanical and scientific matters. R. E., of N. Y.—There is nothing new in your invention. C. R., of N.Y.—It is doubtful about your being ! able to hold a claim to a combination, as the devi-ceajaeem not to depend upon each other. J. T., of Troy—Yours will appear next week. Money received on account of Patent Office business for the week ending Saturday, April 2 L. B. A,, of Pa., $30; H. G. R., of Tenn., $5 ; C. D. B., of Ct., $25; G. G-, of N. Y,, $15; A. H. R , of Pa , $55; J T. D., of N. Y., $60; O. S. J., of Ct., $20; A. S., of N. Y , $8, W. B., Jr., of N. Y.,$475; T. L. J., of Miss., $60; R. F., of Ot., $25; D.T.. of N. Y., $25; T.S. G., of N. J, $25. Specifications and drawings belonging to parties with the following initials have been forwarded to the Patent Office during the week ending Saturday April 2 :— H. G. R., of Tenn. ; E. V., of N. Y.; D. T., of N Y.; C. D. B , of Ct ; T. S. G" of N.J.; A M.S. o LAla.; O S J.,of Ct.; F. F., of N. Y.; A. S., of N Y.; H.G.DeW., of N. Y.; W-Z, of 111.; IL 0 Ct.; A S. NofPa. ; R. F., of Ct.