The following inventions have been patented this week, as will be found by referring to our List of Claims on another page :— Show Plow.—Andrew Hotchkiss, of Sharon Valley, Conn., has invented a new plow for excavating snow. L. can be used as an ordinary snow plow in light snows, and when a deep snow occurs, or the snow accumulates in a cutting, one of these plows attached to the front of the locomotive will act as an excavator, and'dig the snow away in blocks. Potato Digger.—A new potato digger has been invented by Jacob E. Hardenburgh, of Fultonville, N. Y., which consists in the combination of an adjustable share and grating, with horizontal and revolving arms, on a suitable framing and wheels, arranged relatively with each other, to dig the potatoes and throw them in ridges on the surface of the ground. Galvanic Gas Lighter.—This apparatus (which will be found fully described and illustrated on page 320, Vol. XII, Scientific American) is the invention of S. Gardiner, Jr., of New York City. It consists in placing a fine coil of platinum wire over the burner, which is made red-hot by the passage of the electric force, and the gas impinging on it becomes ignited. By this means any number of burners may be turned on and lighted instantaneously. It is a valuable invention. Extension Table.—This table has slides of sheet metal plate, which are bm so %s to form tubes, each of which has externally a dovetail tongue on one side, and an inversely corresponding groove on the inner side, so that the tongue of one slide will fit into the groove of the other. By this means the perfect working of the slides is obtained, and the table is rendered stiff and firm ; it is not likely to get out of repair. It is the invention of Edwin A. Curley, of Westport, Conn. Cutting Slots for Stiles in Wash-boards.—O. L. Reynolds, of Dover, N. H., assignor to Hiram F. Snow, of the same place, has invented an improved machine for cutting zig-zag slots in the stiles or hill pieces of washboards, to receive the ends of the corrugated sheet metal plate. It consists in having a wheel provided with a zig-zag cutting edge placed on a shaft over a bed having a longitudinal groove made in it to receive tho stiles or side pieces. The wheel, as it is turned, cuts the zig-zag curves or slots in the stiles. Saw-set.—The class to which this saw-set belongs is that in which a punch is employed to bend or give the set to the teeth of saws. The invention consists in attaching the punch to a swinging or vibrating bar, which is operated by a cam and spring, and using in connection with it a beveled inclined bed and set screws, whereby a greater or less set may be given to the saw as desired, and the implement may be applied to the saw with the greatest facility, thus setting saws in an expeditious and perfect manner. It is the invention of Edward Marshall, of Brooklyn, N. Y. Improvement in Belting.—The object of this invention is to prevent the slipping of belts on small pulleys when driven by a larger one. It consists in leading a belt from the large pulley round the back, to and round an intermediate pulley on a third shaft; from this intermediate pulley the belt is carried back again around the small pulley to the large one. By this arrangement the smallest pulley can be driven by a large one without any danger of the belt slipping. The arrangement is the invention of Benjamin Chester, of this city, who has assigned it to V. H. Bur-nap, of Lowell, Mass. Cutting Metai. Tubes.—This invention consists in having a metal collar provided at one end with a flanch, which fits in a recess in a circular stock fitting loosely on the collar. The opposite end of the collar has a ring secured upon it, by a screw passing through them both, and pressing against the tube to be cut, which is fitted inside the collar. The stock is fitted and works between the flanch and ring, and a cutting tool is placed in a socket attached to the stock. The tube is cut by rotating the stock on the collar, the cutter being fed to its work by a screw worked by hand. It is especially applicable to cutting gas tubes, and is the invention of T. J. Lloyd, of Pottsville, Pa. Casting Hinges.—The object of this invention is to produce a hinge in which all the adva ntages of the best drilled and wired hinges are obtained, and which is, in some respects, superior, at a cost scarcely exceeding that of the pivot hinge, which is formed by casting the two parts together, with teats and corresponding recesses at the center of the joint. The invention consists in the introduction of a wrought iron pin, or pins, into the center of the joint, by the molding and casting process, in such a manner that they extend through the knuckle or knuckles of one leaf of the hinge, and protrude so as to form pivots entering into, but not passing through, the knuckles of the other half of the hinge. It is the invention of Nicholas A. Fenner, of Providence, R. I., and assigned to the N. E. Butt Co., of this city. Circular Saw Machine.—This invention consists in attaching the saw guides to a forked or V-shaped bar, which is fastened to a collar on the saw arbor, and having the pillar blocks which receive the bearings of the arbor pivoted to the frame; the bearings being fitted in the pillar blocks in a peculiar way, and the outermost pillar block and bearing being rendered adjustable longitudinally, whereby a longitudinal play or movement is allowed the saw arbor, and consequently a lateral play is allowed the saw, so that it may conform or give to the spring of the log ; and the " dip " of the saw is regulated, or more or less " clearance " can be given it, as may be required. It is -the invention of A. C. Martin and Mahlan M. Wombaugh, of Cincinnati, Ohio, who have assigned it to A. C. Martin and R. Ashcraft, of the same place. Casting Car Wheels.—A. A. Needham, of Rockford, 111., has invented a new method of performing this operation, by which he overcomes the difficulty hitherto attending the casting of perfect car wheels, in consequence of the unequal cooling of them, produced by casting with a chill, in order to harden the periphery. Wheels cast with a chill are liable, from the cause above alluded to, to crack, and the iron prevents it from assuming that crystalline structure of cast iron which is best adapted for strength. The invention consists in using two different kinds of iron, hard and soft, and having the mold placed within a revolving flask, the melted hard iron being first poured into the mold, which, by centrifugal force, will be pressed hard to the edg of the mold, thus forming a periphery of hard iron ; the softer iron can be aftewards poured into the mold, to form the body of the wheel, and the whole being allowed to cool * gradually, the wheel will contract equally j throughout its mass