Broken peat--the fragments and waste of the cut or moulded blocks, and peat as obtained by plowing and harrowing the surface of drained peat-beds--may be used to advantage in the _stair grate_, fig. 1, which was introduced some years ago in Austria, and is adapted exclusively for burning finely divided fuel. It consists of a series of thin iron bars 3 to 4 inches wide, _a_, _a_, _a_, ... which are arranged above each other like steps, as shown in the figure. They are usually half as long as the grate is wide, and are supported at each end by two side pieces or walls, _l._ Below, the grate is closed by a heavy iron plate. The fuel is placed in the hopper _A_, which is kept filled, and from which it falls down the incline as rapidly as it is consumed. The air enters from the space _G_, and is regulated by doors, not shown in the cut, which open into it. The masonry is supported at _u_, by a hollow iron beam. Below, a lateral opening serves for clearing out the ashes. The effect of the fire depends upon the width of the throat of the hopper at _u_, which regulates the supply of fuel to the grate, and upon the inclination of the latter. The throat is usually from 6 to 8 inches wide, according to the nature of the fuel. The inclination of the grate is 40 to 45° and, in general, should be that which is assumed by the sides of a pile of the fuel to be burned, when it is thrown up into a heap. This grate ensures complete combustion of fuel that would fall through ordinary grates, and that would merely smoulder upon a hearth. The fire admits of easy regulation, the ashes may be removed and the fuel may be supplied without _checking the fire_. Not only broken peat, but coal dust, saw dust, wood turnings and the like may be burned on this grate. The figure represents it as adapted to a steam boiler. 6.--_Hygroscopic water of peat fuel._ The quantity of water retained by air-dried peat appears to be the same as exists in air-dried wood, viz., about 20 _per cent._ The proportion will vary however according to the time of seasoning. In thoroughly seasoned wood or peat, it may be but 15 _per cent._; while in the poorly dried material it may amount to 25 or more _per cent._ When _hot-dried_, the proportion of water may be reduced to 10 _per cent._, or less. When peat is still moist, it gathers water rapidly from damp air, and in this condition has been known to burst the sheds in which it was stored, but after becoming dry to the eye and feel, it is but little affected by dampness, no more so, it appears, than seasoned wood. 7.--_Shrinkage._ In estimating the value and cost of peat fuel, it must be remembered that peat shrinks greatly in drying, so that three to five cords of fresh peat yield but one cord of dry peat. When the fiber of the peat is broken by the hand, or by machinery, the shrinkage is often much greater, and may sometimes amount to seven-eighths of the original volume.--_Dingler's Journal, Oct. 1864_, _S._ 68.