158 SECTIONAL ADDRESSES 
least 0:5 for domestic heating, power being 0-75 to 1-0, and lighting 
threepence to sixpence. Local rates account for some of this difference, 
but distribution and office expenses are the chief part. Both are nearly 
constant expenses for a given maximum demand, and are directly reduced 
by a high load factor. The mains do not wear out faster if they carry 
current for more hours a day, nor does it cost more to read a larger 
number of units on the meter, nor to make out a larger bill. Also the 
cost is decreased by a greater density of load over an area. More con- 
sumers per mile of low-tension cable merely mean more feeding points 
and larger high-tension mains or a higher tension, and to obtain a more 
nearly universal demand and a larger demand per house is simply a matter 
of reduction of selling price, while they will themselves help greatly to 
reduce the cost further, if the process can once be started. 
The historically first use of electric energy—electric lighting—is now 
so general where a supply is available, that no great increase will be 
obtained by a reduction in price, and enlargement of areas of supply 
means country districts with sparse population. Motive power in factories 
is now supplied to the extent of one-half from electric mains, and a con- 
siderable part of the other half is electric drive from private plant, where 
industrial steam is required and a steam generator is easily added. These 
may come into the general scheme, but will not greatly increase the 
public demand. The old shop engine is rapidly disappearing, and the 
process will not be much accelerated by cheaper electricity, as in the great 
majority of cases the electric drive from a public supply already costs less 
than the shop engine. 
There remain as comparatively little developed directions for new 
demand the fields of domestic heating of all kinds and electrification of 
railways. In these a successful competition with other methods depends 
largely on cost. Electric cooking, hot water supply, and house warming 
must be brought down to a figure not greatly exceeding that involved in 
the consumption of raw coal, if anything like a general adoption is to be 
brought about. A figure of one halfpenny begins to be persuasive, but 
above that the added convenience does not outweigh the cost in the view 
of most people, and even that figure only meets the competition of gas 
on equal terms, if the price of gas is eightpence per therm, and there are 
signs that this may be reduced. The possible demand is enormous, for 
the present consumption of domestic fuel is some forty million tons per 
annum, more than three times the whole of the coal used in electric 
supply for all purposes. Owing to the large losses of energy in the steam 
engine, with boiler losses and transmission, at the best only 20 per cent. 
of the total heat in the coal burnt is delivered to the consumer. The 
domestic fireplace has a rather better efficiency, but it is not used so 
economically, so on the whole the amount of coal used will be much the 
same. ‘The station uses a cheaper fuel, but loses on the cost of distribu- 
tion. As domestic heating yields a high load factor, and offers scope for 
a high density factor, it will help greatly in lowering distribution costs. 
The railways offer a large, though not so large a field. This was 
explored by Lord Weir’s committee of 1931, and the finding was 
favourable. But it was not universally accepted in its entirety, and the 
margin of advantage claimed was obtained by economies of doubtful 
