38 Power and its Transmission. 



duction of cold. It does not suffer, as steam does, from radia- 

 tion and condensation. The first development to any large 

 extent was in connection with the boring of the Mont Cenis 

 Tunnel. From this it has extended to a variety of uses where 

 power is required, more especially in coal mines, where to 

 a distance of three miles or more from the mouth of the pit 

 power of any other kind would be impossible to transmit. After 

 the investigations to which he had referred had been made, the 

 Birmingham Company obtained an Act of Parliament, with the 

 sanction of the municipal authorities, for the construction of the 

 necessary works to utilise the system for supplying power to 

 Birmingham manufacturers. It was calculated that of the 

 amount of compressed air transmitted from the central station, 

 a maximum percentage of 84 per cent, could be obtained by 

 the consumer. The average price they proposed to charge 

 is fivepence per thousand cubic feet, and this would entail 

 to the consumer a cost of £6 14s. 6d. on the best per- 

 centage, and £ij on the minimum percentage per horse-power 

 per annum. The system would not be economical applied to 

 large engines of 100 horse-power and over. There are two very 

 strong recommendations in this system most satisfactory to 

 the consumer : — these are, that the quantity supplied can be 

 measured with the accuracy of a first-class gas meter; — and 

 that no heat or fire can arise from it. Speaking of power 

 as developed by water under high pressure and available 

 for supply, Mr. Wilson said this arrangement was first car- 

 ried out at Hull, and has since been worked in other towns, 

 but it is very expensive ; — the use of a hydraulic motor 

 involves a year power unit cost of from ^"40 to £60. As for 

 electricity, it remains for some future Watt to devise a plan 

 whereby it can be produced and applied as a force with suffi- 

 cient economy to compete with the other sources of power. 



In the foregoing remarks the cost of the year power unit is 

 in all cases taken as including coal, oil, stores, labour, deprecia- 

 tion at 5 per cent., and interest on outlay at 5 per cent In the 

 larger class of engines the two latter items in some cases exceed 

 the whole of the former, while as they reduce in size the pro- 

 portion of coal cost rises rapidly. 



