390 Intelligence and Miscellajieous Articles. 



readily to understand the construction of the ventilator and the mode 

 of its operation. The machine could have scarcely been tried under 

 circumstances more unfavourable to its success than in this instance ; 

 for independent of the additional friction caused by drawing a large 

 quantity of air through ways of little more than 11 feet area, 

 owing to the men having been watered out of that part of the mine 

 where the principal works have recently been carried on, it was found 

 needful to change the direction of the air- ways, and, in consequence, 

 it is at present conducted through temporary passages, which are 

 ill- calculated for such a purpose, and which permit an immense leak- 

 age of the air into the waste parts of the colliery. The enlarge- 

 ment of the areas of the upcast shaft, which is now only 3 feet dia- 

 meter, and of the air- ways, is now in progress, which, when com- 

 pleted, will materially add to the effective performance of the ma- 

 chine. The engine, too, is an old one, and has been injured by long 

 exposure, is less than half the power necessary to work the machine 

 to its full effect, and is of a defective construction. Yet under all 

 these disadvantages and impediments to the development of its 

 powers, the machine worked steadily at 1\ strokes per minute. The 

 diameter of the aerometers is 12 feet, and the length of stroke 4 feet. 



Therefore 12 feet diameter = 113 feet area x 2 = 226 feet area 

 and 4 feet stroke x 2 = 8 x 7^ strokes per minute 60 feet velocity 



= to 13,560 cubic feet of 

 air drawn out of the mine per minute. The greatest quantity of air 

 passing through this mine previous to the erection of this machine 

 was 3000 cubic feet per minute ; whilst this machine, if worked to 

 its full extent, is capable of drawing 40,000 cubic feet per minute. 

 By increasing the diameter of the aerometers to 15 feet, then 

 70,000; and if to 25 feet, then 125,000 cubic feet of air per 

 minute would be drawn out of the mine, provided the engine-power 

 was also increased. No sooner was the machine set to work, than its 

 effects were immediately felt in every part of the mine. Stalls in 

 which the fire-damp was so prevalent that it required the utmost 

 caution to be used even with the Davy lamp, the cylinders of which 

 were so heated as to require to be frequently taken into another part 

 of the mine to be cooled, were cleared of this dangerous enemy as if 

 by magic, and all indications of the presence of fire-damp vanished ; 

 indeed, so effectually has the machine removed all apprehensions of 

 danger, that naked lamps and candles are now substituted for the 

 safety-lamp. Even thewaste parts of the mine, which are at a consider- 

 able distance from the direct course of the air- way, and which were so 

 foul and fiery as to render the introduction of even a safety-lamp into 

 it very hazardous, were unexpectedly, and to the astonishment of the 

 men, completely cleared. The abandoned stalls, which have hitherto 

 been magazines of explosive air, can now be entered with safety with 

 a candle ; and the whole atmosphere of the mine is so much improved 

 and purified, that, according to the concurrent testimony of both 

 masters and men, a collier now cuts three tons of coal with less 



