Geo. H. Dodge, of Phila., nas taken measures bo secure a patent for a useful improvement in screw cempression cocks, the nature of which improvement consists in making the valve detached froro the screw, and furnishing it with a stem passing entirely through the screw to the outside of the cock. The principal object of this improvement is to allow of the valve being ground when 16 gets loose, and this can be effected while the cock is in place by aim-plyrelieving it from the pressure of thesciew, and turning it in its seat by the part of the stem protruding through the screw. The valve being detached from the screw makes it fit correctly to the seat, as it is not subject to a racking action, consequent upon any want of accuracy in the screw.