required for these fires is very small, and less than with coke firing. I
find that 0.08 in. vacuum is sufficient with tar fires, and 0.25 in. for
coke fires. The fires would require less attention with more draught and
larger tar supply, as the apertures do not so easily close with a sharp
draught, and the tar is better carried forward into the furnace. A regular
feed of tar is required, and considerable difficulty seems to have been
experienced in obtaining this. So long as we employed ordinary forms of
taps or valves, so long (even with filtration) did we experience
difficulties with the flow of viscous tar. But on the construction of
valves specially designed for the regulation of its flow, the difficulty
immediately disappeared, and there is no longer the slightest trouble on
this account. The labor connected with the feeding of furnaces with coke
and cleaning fires from clinker is of a very arduous and heavy nature.
Eight coke fires are normally considered to be work for one man. A lad
could work sixteen of these tar fires.