The position that the pyrometer should occupy is subordinate to the
construction of the furnace. Fig. 6 shows the type which is most
employed.

[Illustration: Fig. 6.--The Pyrometer mounted on a bone-black furnace.]

In a furnace with lateral fire-place, cc are the heating cylinders,
and dd the cooling cylinders. C D is the plate on which are mounted
vertically the former, and from which are suspended the latter, b shows
the pyrometer, the length of which must be such that the manometric
apparatus shall stand out one or two inches from the external surface of
the wall, while its tube, traversing the wall, shall reach the very last
row of heating cylinders.

That the apparatus may form a permanent regulator for the stoker it is
well to adapt to it an arrangement permitting of a graphic control of
the work accomplished and signaling by means of an electric bell when
the temperature of the gases in the furnace descends below 480 deg. C. or
rises above 550 deg. C.


APPLICATION OF THE APPARATUS TO BRICK FURNACES AND IN THE MANUFACTURE OF
CHEMICAL PRODUCTS.

The operation of heating brick furnaces is generally performed according
to empirical methods, the temperature having to vary much according to
the products that it is desired to obtain. It is necessary, however, for
a like product to maintain as uniform a temperature as possible. These
observations are particularly applicable to continuous furnaces such as