Drawing of Martin's patent grate and furnace door fitted to Cornish boiler

Drawing (scale 1:12) showing 2 views of Martin's patent grate and furnace door fitted to Cornish boiler. In glazed frame

This is a form of door for a boiler furnace, patented by Mr. W. A. Martin in 1867. It is hinged at the top and balanced so that it will stand at any angle at which it may be placed. When it is opened for stoking the fire it is turned up so as to stand full open, opening outward; but when it is desired to admit air above the grate, to prevent smoke after putting on fresh coal, the door can be set open a little way opening inward, in which position its curved surface acts as a deflector, driving the inflowing air down upon the " dead-plate " in front of the grate, so that it shall impinge upon the fuel.