215 
plosion. The steam fan was about to be put in operation near 
Wakefield, and its simplicity of action recommended it to 
all who had seen it. Mr. Nasmyth explained the action of 
the fan by referring to a drawing which he had prepared. 
On the fan being made to revolve rapidly, the volumes of 
air contained between the vanes were forced out, while fresh 
air rushed in to supply its place. He recommended that the 
steam engine should be placed in direct communication with 
the fan, and that the engine should have a very short stroke. 
A speed of 300 revolutions per minute was thus very easily 
attained, and 20,000 cubic feet of fresh air per minute could 
be forced into a pit with a fan whose vanes were eight feet in 
diameter. A fan whose vanes were double the diameter would 
be amply sufficient to ventilate the largest mine in Britain. 
The whole apparatus, including steam engine, would cost 
about £160. With so efficient a means of ventilation, 
attainable at so small a cost, it would be a disgrace, in these 
times of civilization, if such wholesale destruction of human 
life were allowed to occur. 
The second communication, being upon an apparatus for 
effecting the same important object, was read by Mr. Biram. 
DESCRIPTION OF THE FAN ERECTED FOR THE VENTILATION 
OF THE HEMINGFIELD PIT, BELONGING TO EARL 
FITZ WILLI AM, AT ELSECAR. BY B. BIRAM, ESQ. 
This fan, which is eight feet diameter and nine inches 
wide, has eight vanes, which are so arranged that each 
forms the segment of a screw which revolves in the same 
plane. The angle of the extremity or outer edge of the 
vanes is about 23 degrees with the plane of rotation, 
making the pitch of the screw about 10 feet 10 inches.. 
The area for the passage of air through the fan is about 
47 superficial feet, which, multiplied by 10 feet 10 inches* 
— the pitch of the screw, — gives 509 cubic feet as the. 
