.S7A 1 \\-ll.UA.M SIEMENS, F.R.S. 2OJ 



there Mini thru suggested ;i means by which the transmitting 

 power of a large electrical conductor might be almost indefinitely 

 increased by giving it the form of a hollow tube through \\hieli 

 \\ater mi^ht l>e made to flow. It is evident that cold water flow- 

 ing through such a conductor would prevent an inconvenient 

 accumulation of heat in the metal, and it would not be difficult to 

 i in roduce and discharge the flowing water at intervals from the 

 ]iipe without interfering with the necessary insulation of the con- 

 ductor from the earth. 



Our last experiment proved that intense heat can be generated 

 in the electric conductor, and I now propose to bring before you 

 another simple experiment, to show how readily the heat so 

 generated may be employed for heating water. I will immerse the 

 spiral coil of platinum wire which I hold in my hand in a glass 

 jar containing about two pints of water, and after closing the 

 electric circuit you will perceive, in the course of a minute or two, 

 that the water is brought to the boiling point, nor would this 

 mode of heating water in small quantities be expensive if currents 

 were laid on to our houses from dynamo-electric machines, and 

 who knows whether, in the electrical age towards which we seem 

 to be gravitating, the apparatus before you may not be the common 

 coffee machine of the day. 



After this digression, let us return for a moment to my proposal 

 of last year to convey 1000 horse-power a distance of 30 miles 

 through a conductor 3 inches diameter. 



The electrical resistance of this conductor would be '18 of a 

 unit, and supposing that the total resistance in circuit was made 

 L>! units, which, as I before stated, gives a favourable working 



"18 



condition, it follows that - x 1000 = 72 horse-power would be 

 *"o 



expended in heating the conductor. 



This would represent about 15 Ibs. of coal per hour, a quantity 

 quite insufficient to raise a mass of 1900 tons of copper, with a 

 surface of 132,000 square feet, to a sensibly heated condition. So 

 far from admitting therefore that I have overstated my case 

 regarding the capability of my large electrical conductor, I am 

 convinced, on the contrary, that its sectional area might be safely 

 reduced to one-half that previously given (or its diameter to 2 

 inches), whereby its cost would also be reduced to one-half. 



