342 GEOLOGY OF OHIO. 
Small locomotives have of late years been introduced in a number 
of coal mines in the State to do the work of hauling underground. 
MINE LOCOMOTIVE. 
The first trials of mine locomotives were made in Pennsylvania, in 
the anthracite coal fields, but they are now found in all the coal mining 
states. As compared with stationary machinery and wire ropes, they 
hold their own, but they are objected to by many on account of the 
smoke and gas generated from the coal. In the hands of an intelligent 
mining engineer, who is master of the art of mine ventilation, they can 
be used with perfect safety, but taken where uneducated and unskilled 
men control the mining department, they are dangerous forces, and 
their introduction has frequently led to fatal consequences. 
Wherever mine locomotives are used, it is necessary for the health 
and safety of the miners to ventilate the workings with air, which is 
not allowed to come in contact with the current amidst which the loco- 
motive moves, and a column of wind of 25,000 cubic feet per minute, 
and moving at the rate of 5 miles per hour is required to rid the mine 
of smoke and keep the galleries in a fit state for miners to occupy. 
CoaL CuttTiInc MACHINERY. 
Two coal cutting machines are in use in mines in Ohio—the Lechner 
machine and the Harrison machine. The Lechner was introduced in 
the mines of the Straitsville Central Mining Co., in Perry county, in 
1876, and since that time it has been extended to several other districts 
in Ohio and to a number of the mining districts in Pennsylvania, West 
Virginia, Kentucky, Alabama, Illinois, and Colerado, and last year 
found its way to some of the mines in Great Britain. 
This machine is only 20 inches in height, and can be used in seams 
of coal three feet thick and upward. It is wrought by means of com- 
