528 GEOLOGY OF OHIO. 
The large “ Etna” furnace, at Ironton, has the cone and cup cov- 
ered by an arrangement of sliding doors, so fixed that after the charge 
is on, the cone and the space above it can be entirely covered, so pre- 
venting almost entirely the escape of gas from the furnace. This arrange- 
ment is similar to the one shown in Fig. IV, representing the sliding door 
charger, built by the Weimer Machine Works, at Lebanon, Penn. 
The blowing engines are of the upright pattern, showing very little 
difference in detail, the direct action vertical engine being the one in 
most general use; recent improvement looking toward higher piston 
speed, have been introduced by machine works. One of the more re- 
cent patterns is shown, as to its arrangement of air valves, in Fig. V. 
The object of this arrangement is to admit rapid action of the 
valves, and to reduce their travel or lift. As an illustration of the 
varying speed at which engines are run, the following figures may be 
of interest ; the dimensions of the engine are also given for purposes 
of comparison : 
Cylinders. Revolutions. 
imrodebunnacelComeeee reece 84/7x48// 40 
Brier! EV gh here ieee See ee ee areas 8477x487 36 
W ellston shurnace nies cisco eee ele rere oeneee 48x48” 22 
MiZamhunn ace eeeesseescceeaeeeeecee Areca eaaie wenn aanmeeee 54x48 25 
Hamad ensiurnace ss. occcscncecce eee eee eters neces ASxG 2a 18 
Pine Grove cee cir esos ee ee eee ee aes 48’7x42// 9 to 12 
It being probable that the working of a furnace is largely depend- 
ent upon the blast facilities, the tendency to the increase of. Powe and 
speed of blowing engines is everywhere apparent. 
The use and distribution of gas from the furnace follows at all the 
works the same general plan. In the cases of furnaces using much raw 
coal, the large amount of gas produced has led to its rather careless and 
wasteful use for heating purposes, also many of the furnaces using coke 
are in the habit of charging a certain amount of coal with coke, for the 
purpose of increasing the amount of gas. Where the coal is used in 
large proportion, the large amount of tar, water and dirt carried over 
by the gas necessitates the introduction of reservoirs or wells for the 
collection of this tar at the bottom of the down-cast pipe; these are 
sometimes above and sometimes below ground, the arrangement of the 
pipe consisting of a large expansion or drum of wrought-iron and ma- 
