Improved Kilns for burninrf Lime, 
141 
and 8, and a perspective view, shewing the general arrangement, 
is given in Fig. 9. 
It will be seen by the drawing that the kiln cannot be built in 
the side of a hill, but must have a free passage all round it. 
The kiln is of a rectangular form, with angular buttresses at 
j the quoins and centre buttresses at the ends ; the chimney-flues 
form the buttresses at the sides, and the end buttresses support 
the roof of the kiln-pit, with archways through them on one side 
leading to the lime store ; this extends ahmg the one side of the 
k iln, with sliding doors in the centre to allow a cart to back inside 
it to load in the dry. The other side of the kiln is occupied by 
the approach road, or tramway, from the chalk or limestone 
hill, and the kiln-pits extend across both ends. The width of 
the kiln depends upon the number of fire-holes, e. f/., a three-hole 
kiln requires to be 17 feet (! inches wide. It should never be 
more than 13 feet 6 inches deep, as it is inconvenient to draw 
tlie fire-bars if thev are more than 4 feet long. The heisrht of 
the kiln should be from 7 feet 6 inches to 9 feet above the fire- 
grate. The walls should be 2 feet 3 inches thick, and should be 
held together by two wrought-iron bands with adjustable couplings. 
It will be seen, from Fig. 7, that for a three-hole kiln there 
are four withdrawing holes, situated between the fire-holes. 
The fire-grates for the fire-holes are constructed with cast-iron, 
rectangular, fish-bellied fire-bars, resting on bearing-bars as in the 
fire-grates for the intermittent kilns before described. The with- 
drawing holes are constructed of wrought-iron circular fire-bars, 
1^ inch diameter, 1 foot apart, resting on cast-iron bearing-bars,, 
which, except the centre ones, are parallel, and on which are cast 
a series of lugs perforated with circular holes through which the 
Fig. 7. — Sectio7i of Improved Perpetual Ki.n. 
