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before the accumulation of damp had stopped further pro- 
ceedings, and it was through this aperture that the 
ventilation was effected. The pressure of steam in the 
boiler was 20lbs. per square inch, and on opening the stop- 
cock, the velocity of gas, &c. drawn up the pipes was such 
that a few minutes sufficed to clear the pit of foul air down 
to the clack-door, and the remainder was effected by attaching 
temporary wooden pipes. 
After observing the rapidity with which the air rushed up 
the pipes, and finding that only a comparatively small supply 
of steam was necessary to maintain thorough ventilation 
of the shaft, it was determined to apply the same principle 
to ventilate the workings of a small neighbouring colliery, in 
which not more than ten or twelve persons were employed 
underground. In this instance the shaft is about sixty yards 
deep, and the ventilation had been effected by means of 
wooden air pipes, communicating with the engine chimney, 
the draft of which constituted the ventilating power. The 
ventilation was feeble, and at times almost imperceptible, 
owing to the unfavourable state of the atmosphere ; and the 
circumstance of the case, in other respects, being favourable 
to the application of the steam ventilator, similar to that 
already described, a nine feet length of ten inches cast iron 
pipe was fixed upon the wooden air pipe leading from the 
pit to the chimney, and the steam jet supplied from a boiler 
close by was fixed in it ; there was also a slide or damper, 
placed between the cast iron pipe and chimney for the 
purpose of stopping the communication with the latter. 
The orifice of the jet piece was ll-l6ths of an inch in 
diameter, and the boiler pressure ranged from 20 to 30lbs. 
per square inch. The effect produced by these alterations 
was a most decided improvement in the ventilation of the 
mine, and although it has been found inconvenient to keep 
the apparatus constantly in operation, owing to the con- 
