179 Steam Engines. 
INTELLIGENCE AND MISCELLANIES. 
4. Foreien. 
Foreign Literat d Science ; extracted andt lated by Prof. J. Griscom. 
1. Steam-Engines of extraordinary dimensions.—The cop- 
per mines in the neighborhood of Redruth, in Cornwall, 
whose workings have been recently resumed, contain former 
workings of great extent, which it was necessary to drain 
out. Their length is about a mile, and their depth at the 
level of the canal, which conveys their water to the sea, is 
about 900 feet. In order to drain this old opening, and te 
dig deeper, Arthur Wolf bas erected three steam engines ; 
the one which isin the western part of the mine has a cylinder 
70 inches in diameter, and moves pumps at the depth o! 
about 400 feet. A second machine is placed in the middle 
and a third in the eastern part of the mine. These two last 
have cylinders 90 inches in diameter, and the motion of their 
pistons is ten feet. Each machine has six boilers, three of 
which are so disposed that they can be heated by two fires, 
and are sufficient to move the machine. The other three 
are in action when the first stand in need of cleaning or re- 
pairing. These three enormous machines, are constructed 
inthe nicest manner, having all their parts in the most per- 
fect proportion. Though they are the largest machines hith- 
erto known, their motion is smooth, and free from shaking. 
The pistons making from ten to twelve strokes per minute, 
with perfect regularity. 
The first of these machines consumed in 35 days $800 
bushels of coal, and lifts every day nearly 39,000,000 gal- 
Jons of water, a result which surpasses that of any other ma- 
chine known. 
The weight of these gigantic machines is as follows : 
The cylinder, without its cap and bottom, weighs 27,000 Ibs. 
The stem of the piston and its axis weigh 56,000 Ibs ; that 
Which moves the pumps and the iron connected with them, 
about 90,000 Ibs. and if we add to this the column of water 
