The Secretary of the Treasury publishes a notice to the manufacturers of boiler 'iron, calling their attention to the provisions of the new Steamboat Law, which requires, " That all plates of boiler iron shall be distinctly and permanently stamped in such manner as the Secretary of the Treasury shall prescribe, and, if practicable, in such place or places that the mark shall be left visible after the plates are worked into boilers, wit.h the name of the manufacturer, the quality of the iron, and whether ur not hammered, and the place where the same is manufactu:ed," The Secretary says, in pursuance of the authority vested in him by this act, that, in fu-ture, all iron to be used in boilers of steam vessels must be clearly and distinctly stamped in not less than three places on each sheet or plate, as follows, viz" at two diagonal corners, at a distance of about four inches from the edges, and also about the middle of such plate or sheet, with the name of the manufacturer, and the name ot the place where manufactured, designating the latter by the name ot the city, town, or county, and also State.