GRATE, the iron cage which supports the coal for a common fire. Considerable improvements have been made of late years .in the construction of common domestic grates. Our forefathers simply added an iron cage to the old form of fire-place built originally for burning a pile of wood. This was a large square-sided recess, with a very wide opening for the chimney. Count Rumford pointed out the disadvantages of this, and the principles upon which they should be remedied. See CHIMNEY. In the modern grate, the filling up of the square cavity recommended by count Rumford, and also his plan of lowering and narrowing the throat of the chimney, are usually effected by iron plates forming part of the grate. These plates are readily heated, and with equal read iness radiate and reflect the heat into the room, and thereby effect a considerable saving of coal, besides which the grate itself is brought forward level with, or even projecting beyond, the walls of the room, whereby the radiation from the heated coal is utilized to the utmost. One of the most effective as well as elegant forms of grate is that which consists simply of a large square iron plate set nearly flush with the wall, in the middle of which is a hemispherical cavity with bowed bars in front, and a into the chimney in the upper part of this cavity. When there is a fair draught, this form
of grate gives a good fire, and effects the maximum economy of fuel for an open fire place (which of course is always somewhat wasteful compared with a stove). The curved surface behind and above the fire radiates and reflects into the room from every part of its surface. and the plate flush with the wall, which is heated by conduction, may be regarded as a part of the room, and thus the main condition of economy is effected, viz., throwing as much as possible of the heat, into the room, and'allowing as little as possible to go up the chimney. A lining of firebrick or of fireclay, molded to the form of the back of the grate, is useful in retaining the beat which is necessary for complete com bustion of coal; the firebrick, being a bad conductor and an excellent radiator, becomes red-hot on its surface next to the coal, and this heat is not carried away, but is radiated into the lire, and assists in burning the carbon of the smoke. The conditions for securing an effective draught are treated under CHIMNEY.