I claim, 1st, The combination of the chamber, F, provided with the short pipes, p p', and the pipes, p", with the pumps, G H, and the chambers, C D E, substantially as and for the purposes described. 2d, The combination and arrangement, for the purpose described, of the chambers, C D E F, pipes, p p' p", P P' P", and pumps, G H, the latter working alternately, so as to maintain a constant pressure upon the water in the chambers, substantially in the manner specified. 71,986.--TACK HAMMER.--Thomas A. Conklin, New Britain. Conn. I claim, as a new article of manufacture, a tack hammer, constructed in the manner and With the characteristics herein specified, for the purposes set forth. 71,987.--FLOOR CLAMP.--Wm. Conner and C. W. Mitchell, Wilmington, Del. We claim the combination of the frame, a, with the screws, b and d d, with the wedge blocks, e e, wedges, f f, and plates i i, constructed and arranged, as herein described, to operate as a clamp for clamping ship timber, flooring, and other carpenters' work. 71,988.--BUTTON.--Geo. Cooke, Winchester, Mass. I claim a button or stud, its shank attached by means of a disk formed concave, and subsequently compressed, substantially as described. 71,989.--HARVESTER.--Francis C. Coppage, Terre Haute, Ind. I claim 1st, The combination of the double or alternate step wheel, E, having the inclined steps, e e e, with the two stepping-dogs, D D', and the springs, x x, when the said parts are constructed and arrange substantially in the manner and for the purposes described. 2d, The combination and arrangement of the adjusting rod, n o", with the cylindrical sleeve, O', the sleeve or slide, O"', the post, P, and the reel, O"', in such a manner that while the post P, supports the reel, the elevation of the latter is adjusted by the compound rod, n o", substantially as and for the purposes specified. 3d, The rod, H, having the crank, h, and the worm, h', in combination with the worm segment, i, the shaft, I, the winding arm or segment, i', and the chain, K, substantially as and for the purpose specified. 71,990.--MACHINE FOR STRETCHING CLOTH.--A.C. Corpe, Stafford, Conn. I claim, 1st, The two gear clamps, B B, composed each of two wheels, a a', one placed above the other, and the upper wheels arranged so as to be capable of adjustment, both vertically and laterally, substantially as shown and described. 2d, The arrangement of gearing, as shown, in connection with the gear clamps, B B, and roller, C, whereby an equal movement of the clamps is insured, substantially as shown and described. 3d, The supplemental frame, E, provided with the roller, D, upon which the cloth is wound, in connection with the gearing, k u, clutch, o, driving pulley, m, and shaft, l, all arranged substantially as shown and described. 71,991.--ROLLER FOR DRESSING.--Benjamin R. Cotton, Lewiston, Me.