448 Mr. Alan A. Campbell Swinton [April Ut, 



is at any rate very interesting. Obviously such a scheme, if it could 

 be practicably worked, would have enormous advantages in many 

 ways, and in one, perhaps not the least, that it might enable seams 

 to be worked which, owing to their thinness, are now quite unprofit- 

 able. On the other hand, no saving of residual or by-products would 

 appear feasible, unless, indeed, from the washing of the gas ; and it 

 appears very problematic what area of coalfield could be tapped from 

 a single borehole without stoppage resulting from the falling in of 

 the roof when no longer supported by the coal. At the same time, 

 when working near the boundaries of a property, it would be difii- 

 cult to know whose coal was being gassified. Anyway, the scheme 

 is apparently to be given a practical trial, and this certainly seems 

 desirable. 



There are still nineteen years to elapse before the purchase of the 

 London electric companies can take place under the Act of 1888, and 

 nineteen years is a long time, having regard to the present rate of 

 progress in electrical matters. If a suggestion may be hazarded, it is 

 that when the time comes it will probably be best for the London 

 County Council, or whoever the ultimate purchasing authority may 

 be, to confine themselves to the distribution of electricity, which by 

 that time they will no doubt be able to purchase very cheaply 

 wholesale from others, and not to embark directly upon electricity 

 manufacture, which by then will in all probability be carried on at 

 the coalfields on an enormous scale alongside of chemical manu- 

 facture, metallurgy, and other processes of which we now know but 

 little. 



When the coal and oil and also the peat are exhausted, wliat 

 then ? The date may be distant, but come it must, and that within 

 a period short in comparison with our past civilization. 



The water power existing on the earth, when all harnessed, would 

 only supply a very small percentage of the demand for power, light 

 and heat. The utihzation of the tides does not appear a very 

 hopeful project, any more than does the utilization of the internal 

 heat of the earth. There remain the energy dependent on atomic 

 transformation, the availability of which the highest authorities 

 appear to regard as probably impracticable, and the radiant energy 

 that reaches this planet from the sun. The latter, as calculated by 

 Sir J. J. Thomson, amounts on a clear day to no less than 7000 

 horse-power per acre, or about 4,500,000 horse-power per square mile 

 of the earth's surface. 



Here is obviously an ample supply of energy sufficient for all pur- 

 poses provided it can be converted into work by some reasonably 

 efficient process. This should not prove impossible, and we have 

 therefore here a problem for the physicist of the utmost importance 

 to the race. 



In conclusion, it may be pointed out that all the many interesting 

 developments which have been discussed are based upon discoveries 



