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of air, and by turning the wheel one way or the other, I can 

 readily cause a current of air to pass through the passage, 

 in either direction, at the rate of 900 to 1,000 feet per 

 minute. I think there cannot be a doubt of its great appli- 

 cability for ventilation of public buildings, the holds of ships, 

 and also for mines. The construction is simple and econo- 

 mical, the space which it would require would be small, and 

 the current of air which it would propel would far exceed in 

 quantity that of any other wheel of the same dimensions. 



Martyn J. Roberts, Esq., F.R.S.E., then read the follow- 

 ing paper, — 



DESCRIBING THE PROCESS OF BLASTING BY MEANS OF 

 GALVANISM. 



It is only within a short period that the science of electricity 

 has in any manner been applied to the arts, but it offers to 

 our use a powerful agent that will soon be directed in a 

 thousand ways to the improvement of our chemical processes 

 and manufactures. We have already its assistance in the 

 rapid transmission of intelligence by the galvanic telegraph — 

 in the multiplication of engraved plates— in the art of gilding 

 and silvering metals — in assaying ores — and lastly, in that I 

 now bring under your notice, the firing of gunpowder in 

 blasting rocks, either in quarries, mines, or subaqueous opera- 

 tions. This application of the electric fluid was carried into 

 effect by me, long before the discoveries I have mentioned, 

 for it is now many years since I attempted to introduce it into 

 the mining district of Cornwall, and it is right that it should 

 have your first and most earnest attention, it being mainly 

 directed to the saving of life, and preservation from injury, 

 to the poor labourer, who, by the use of the old process of 

 blasting, was too often unhappily deprived either of life. 



