S. H. H., of Ind.—Your method of rendering a coffin impervious to air is not new. Such a system is practicable , but experience has shown that it is not profitable. S. T. V.,ofN. Y.—Howe does not and cannot claim the stitch formed by hia machine. His claim ia confined to the particular device for forming this stitch. One patent cannot be made to cover a result, and the mode of producing that result. M. C., of Mass.—You inquire if a patent could bo obtained for a bedstead to keep out bed bugs by having strips of zinc and copper round the legs, rails, &c, so as to get up a galvanic action. The same thing having been applied to trees to keep insectsfrom ascending, no patent couldbe secured for this change of application. It is our opinion that bed bugs would not be "?shocked" by this device. S. S., of Pa.—Fine white sand mixed with plaster of Paris and alum boiled together, we think, will form an improved cementforburr stones. S. W, B., of N. Y.—India-rubber cement would be the best for securing your rubber pump valves. It is made by cutting india-rubber into shreds, and dissolving them in naphtha or turpentine kept in a tight vessel in a warm situation, and stirred frequently for two or three days until it attains to the proper consistency. A. & M., of Fla.—Howell's machine for handling hides, illustrated in Vol. II of the Soi. AM., was successfully operated at that time, but we have heard nothing of it for some y eara past. J. L.,of N. Y.—It ia not necessary that a person should be able to execute the various branches of mechanical labe* over which he is superintendent in order to be competent to direct in a proper manner. A good architect need not be a practical carpenter, joiner and mason. In England, as in this country, architects are usually educated to the profession, and do not rint' ordinarily from mechanics. There may be many exceptions to this general rule. G. S., of Oregon.—The Alcott concentric lathe is adapted to the turning of chair rounds, broom handles, curtain rolls, &c. Price $25. G. B. M., ofCal.—Ditching or drain digging machines have been patented, but at present we do ot know of one which we can recommend. C. C, Jr., of Mass.—A correspondent informs us that pure metallic cobalt is sold in this city for 8 cents per grain. It can be had of J. L. Fyfe, 116 John street, this city. W. W,, of N. J.—The same power that drives an upright saw should drive a circular one doing a like amount of work. We think you may safely get a circular saw in addition to the upright one in your mill. We have never seen any published rules in regard to driving circular saws of various sizes in cutting different kinds of wood. F. N. S., of N. Y.—The right to use a patented machine is generally embraced in the purchase, but is not absolute, as a patentee can sell the right to manufacture to one, the right to sell to anotherj and the use to another. The power of the patentee is absolute over these three conditions in regard to patented articles. Any person, however, who has the right to use a patented machine, it being hia own, can lend its use to whom he pleases. W. B., of Pa.—Your method of checking the speed of the Atlantic telegraph cable by means of parachutes would not be at all practicable. D. S. M., of N. Y.—Your method of paying out the telegraph cable through a tube has been proposed to us very often before and we have been obliged to tell each proposer that it would not answer. A. Z., of 111.—You cannot procure a patent for an invention which did not originate with you. In all cases the inventor must apply in his own name, and the patent issue to you aa his assignee, W. W. R., of Ohio.—It is neither new nor useful to hang floats of paddle wheels on centers, like blind slats, and attach weights to one edge. For informatfoa in regard to the removal of scale from boilers, we refer you to past numbers of the SCIENTIFIC AMERICAN. C. C, Jr., of Mass.—We would advise you to enter the Lawrence Scientific School at Cambridge. S.S. R, of Texas.—We do not knowof any existing patent for a hand saw, so constructed as to combine a square capable of being adjusted to any angle. The only approach to it is Gorham's patent, illustrated on page 390, Vol. XII., Set. AM. The inch measure ia per-minsntly mirked to the back of the saw blade. N. R.. of N. C.—It iaperfectly legal to assign an invention to another before the patent issues. F. A. B., of N. Y.—The method you suggest for propelling vessels by ejecting water from cylinders arranged in their stern ia not new. It has been repeatedly tried in almost every variety of form for the last twenty years, and has been always condemned. J. McQ., of Pa.—The combination you propose for giving motion to pump pistons is not new, nor do we think it useful. Connecting the pump pistons to the walking beam by the usual connecting rods, is the simplest and best means of transmitting motion in the case you describe. W. D., of Jnd,—Presses, with notched bars on either side of the upright post of follower, to be operated upon by pawls attached to the vibrating lever, are in operation all over the country. T. F., of Ohio.—Ice reaches a temperature in the polar regioas as Iowas that of the atmosphere—50. We do not know where you can find Thompson and Vaughn's treatises on solar light and heat. J. B., of N. Y.—Rounding the bottoms of vessels designed to contain liquids, to enable them to be more ' readily cleaned, is an old idea. The plan of cap you ' suggest ia also old. We will advise no inventor to Lmake an application for a patent unless we have confi- dence of success. Money received at the Scientific American Office on account of Patent Office business, forthf weekending Saturday, April 17,185S :— J. McC.,of Ohio, $25; G. Y., of N. Y., $35; C. L. C.,of 111., $25; I. G.,of N. Y., $31; W. S., of Wis., $15; G. S. M.,of III., $30 ; A. E. P., of Vt, $30; J. P., of Mass., $80 ; G. G., of 111., $30; D. J. W., of Ohio, $55; J. S. ofN. Y., $30; L. & G., of Conn., $100; G. B. B, of Conn., $10; A. J. D., of Cal., $10; F. J. G.,of N. C, $55: R. & C., of N. Y., $30 ;* A. C, of N. Y, $30 ; C. P. S-, of Cal., $30; M. &T.,of N. Y., $30; P. C. I,, of L. I, $30 ; J. A. St. J., of Wis., $25 ; L. B. S., of N. Y., $25 ; R. G. S., of 111., $25; J. Y. L., of N. Y., $30 ; W. V., Jr., of N. Y., $30; M. & C, of 111., $30; J. B., of Texas, $10; P. &H., of Conn., $25; II. G. D.,ofKy ,$55; C. W. & Co., of Pa., $25 ; T. H. W. & Bros., of Ga., $25; M. &H., of Pa., $35; G. W. R. S.,of Va., $10; M. D. W., of Ohio, $20 ; W. H. R., of Fla., $55; G. R., of N. Y., $25 ; "\V. J. S., of N. Y., $25 ; R. G. II.. of N. Y., $55; W. J. S., of N. Y., $50; E. B., of Wis., $55; H. R. W., of Ky.,$30; A. McK., of N. Y., $30. Specifications and drawings belonging to parties with the following initials have been forwarded to the Patent Ofllce during the week ending Suhirday, Apiil 17, 138 :— J. McC.,of Ohio; G.Y.,of N. Y. ; J. L. C.,of 111.; D. J. W., of Ohio ; D. H., of N. Y. ; E. G. S., of 111. ; G.R.,ofN.Y.; J. A. St. J., ofWis.; L. 1. S., of N. Y.: W. J. 3., of N. Y. ; C. W. & Co., of Pa. ; P. & IL, of Conn.; H. C, of R. I.; T. II. W. & Bros., uf Ga.; E. G. H., of N. Y.; W. J. ., of N. Y.; K. IT., of Wid .