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The same inventor is engaged in perfecting his system 
of Electric Signalling, so as to indicate the disarrangement 
of doors, and other means of ventilation. In this depart- 
ment, the inventions of Messrs. Ansell and Bagot also call 
for notice. The modes used in the ventilation of mines, 
being a subject so extensive as to make it impossible, even 
to give a summary, within the limits of this paper, the 
writer will, on the present occasion, merely state that, in all 
extensive mines, and especially fiery ones, the old natural 
system of ventilation has been given up for the better 
appliances of ventilating machinery, which may be divided 
into two classes, the Centrifugal and the Exhaust Pump ; the 
former, best represented by the inventions of Faboy, Guibal, 
Lambert, and Harze ; latter, by the Mine Exhauster of the Ate- 
liers de Construction de la Meuse, Liege, Belgium, and Mr. 
Cook's machine, Darlington, England, as an auxiliary to the 
above; Korting's Jet Ventilator is valuable, and very necessary 
as an independent power, for securing ventilation in case of 
accident befalling the ordinary means. Btlgium may, with 
pride, claim the honour of first introducing machinery for 
ventilation amongst themselves, and afterwards diffusing the 
benefits of the same throughout every mining district of 
the world, and enabling mining operations to be conducted 
with so much greater safety and comfort than is possible 
under a natural system of ventilation. 
(6) COAL-GETTING AND DRILLING MACHINERY. 
The application of machinery for getting coal will have 
to be more considered than hitherto. As mming operations 
increase in depth, further necessity will compel every 
effort to be made to lessen the risk to life and property, and 
diminish the cost of production in every possible way. In 
doing this, the use of powder for breaking down the coal 
will have to be dispensed with altogether, and the coal got 
