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4.--_Modes of Burning Peat._

In the employment of peat fuel, regard must be had to its shape and
bulk. Commonly, peat is cut or moulded into blocks or sods like bricks,
which have a length of 8 to 18 inches; a breadth of 4 to 6 inches, and a
thickness of 1-1/2 to 3 inches. Machine peat is sometimes formed into
circular disks of 2 to 3 inches diameter, and 1 to 2 inches thickness
and thereabouts. It is made also in the shape of balls of 2 to 3 inches
diameter. Another form is that of thick-walled pipes, 2 to 3 inches in
diameter, a foot or more long, and with a bore of one-half inch.

Flat blocks are apt to lie closely together in the fire, and obstruct
the draft. A fire-place, constructed properly for burning them, should
be shallow, not admitting of more than two or three layers being
superposed. According to the bulkiness of the peat, the fire-place
should be roomy, as regards length and breadth.

Fibrous and easily crumbling peat is usually burned upon a hearth, _i.
e._ without a grate, either in stoves or open fire-places. Dense peat
burns best upon a grate, the bars of which should be thin and near
together, so that the air have access to every part of the fuel. The
denser and tougher the peat, and the more its shape corresponds with
that usual to coal, the better is it adapted for use in our ordinary
coal stoves and furnaces.

5.--_Burning of broken peat._

[Illustration: Fig. 1--STAIR GRATE.]

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