530 GEOLOGY OF OHIO. 
sonry, terminating the down-cast pipe, a second pipe entering above 
the reservoir to carry off the gas. The arrangement at the Cleveland 
Rolling Mill furnace is shown in the drawing on page 523. The gases 
are distributed under ground through flues of various dimensions to the 
boilers and hot-blast stoves. Fig. VI shows the seetion of the flues at 
this furnace. 
The boilers are generally cylindrical and proportionate in size to 
- the engine and furnace; such boilers, however, being uneconomical of 
gas; in some of the Youngstown furnaces flue-boilers are being sub- 
stituted. At the Himrod Iron Works this change is being made— 
boilers with two flues, replacing, the old cylindrical boilers, and each 
boiler also has anironchimney. The manager states “that since this has 
been done they find that coke alone supplies plenty of gas, no coal being 
needed, and steam enough being furnished to run their large Weimer 
engine at nearly 40 revolutions per minute.” 
These Himrod works are particularly interesting, because they have | 
introduced straight lines in the furnaces and large blast engines as a 
means of obtaining large production. Of their two furnaces, one in 
blast (15 feet in the bosh) made an average of 54 tons per day of iron, 
but on increasing the blast the production was run up to 66 tons per 
day, and consequently the blast capacity for the two furnaces has been 
increased largely. They have now three Weimer engines of 84 in, 
by 4 ft., 66 in. by 4 ft., and 60 in. by 4 ft., all three engines running 
on an average nearly 40 revolutions per minute, are used to blow 
one furnace. The company has, in addition, one horizontal ‘‘ West 
Point” blast engine, 6 ft. by 6 ft., which runs about 25 revolutions per 
minute. 
Hot-blast Stoves. 
For the purpose of heating the blast various forms of stove are 
used, which may be grouped under two heads: the pipe stoves, in which 
the blast is passed through cast or wrought-iron pipes, heated by com- 
bustion of the waste gases of the furnace, fuel not being used for heat- 
ing the blast directly ; and the fire-brick or generator stoves, which 
work on the principle of passing the blast through a chamber filled with 
fire-brick or some similar material previously brought to a high tem- - 
perature. Most of the older stoves are of the pipe pattern ; of this kind 
there are many varieties in use, differing among themselves principally 
