three-fourths inches deep at boss, one and one-half inches of outer end, to be made curving from the boss down, so as to unseat the valve from the edge of the boss, and following up upon the curve until the valve is raised one and one-half inches from the seat; link finished wrought-iron about eleven and one-half inches from center to center, fitted up with brasses, straps, collar, and gibs; section of straps one and one-fourth inches by one-half of an inch diameter, of body one and three-eights inches. The swivel link, of finished wrought-iron, consists of three pieces. The hook and strap joint with a right-hand thread cut on the one and left-hand thread on the other, and the box nut having a right-hand thread in one end and a left-hand in the other; diameter of screw ends one and three-eighths inches, of outside of box two and three-eighths inches; section of straps one and one-half inches by one-half inch thick; hooks three and one-half inches diameter, three and one-fourth inches broad; hook handles and links all finished and arranged in the usual manner. The two cam rods are one and one-half inches diameter by one and five- eighths inches long; jaws five-eighths inch thick; jaws and strap ends finished bright; section of strap one and one-fourth inches by three-eighths of an inch. The cam rods to be supported in two places between the spade handles and guides in main pillow block, with brackets of suitable proportions, carrying a box with two brasses, bored to fit the rods, which must be turned at those places for about twelve inches in length. The cam yokes to be a suitable length to take in 28 1/2-inch cams with sufficient throw to lift the valves one and one-fourth inches from their seats; section at ends three inches by one and one-eighth inches, in center five inches by one and one-eighth inches, ribbed on each side and faced, five-eighths of an inch thick where cam works. The stretchers to be one and three-eighths inches diameter, with collar and check nuts, the slides five inches by one and three- eighths inches. The yokes which the rods attach to have the usual arrangements for that purpose. The space for the nuts to be two inches; cams to be twenty-eight and one-half inches diameter, with sufficient throw to lift the valves one and one-half inches from seat; web one inch thick; face two and one-fourth inches broad, to be held together with a 7/8-inch bolt and nut in each end, and each pair bolted to the collars in sharp by four 7/8- inch bolts. On the pillow block are bolted and keyed two brackets, carrying brasses through which the ends of the yoke works; these brackets to be of suitable form and strength for that purpose and properly fitted up.

The throttle-valve chambers of cast-iron, with an external flange below to bolt it to the branch on the supply pipe; bolts six in number, three-fourths inch diameter, and an external flange at top with cover, stuffing-box, follower, bolts, and nuts. Relief valve precisely similar to those already described for the side pipes. On each side and at the top of the chamber a lug is cast to carry the columns that support the crossbar for the screw to work through; these columns are of finished wrought-iron, one and three-fourths inches diameter at base, one and one-half inches diameter at neck. The part passing through the lug one and one- fourth inches in diameter, with a nut on end and through the crossbar seven-eighths of an inch in diameter, with a nut on the end. Crossbar of finished wrought-iron, eighteen inches from center to center of 7/8-inch hole, through which ends of columns pass; thickness, seven-eighths of an inch; depth at end,