1918.] The N.Z. Journal of Science and Technology. 
49 
The Economics of Electric-power Distribution. 
By E. Parry, Chief Electrical Engineer, Public Works Department. 
Historical Review. 
Power-supply in bulk is now a well-established industry, and has in a brief 
period attained vast dimensions both as regards extent of territory covered 
and the amount of power supplied. No such development could possibly 
take place unless accompanied by a substantial economic gain, and it is 
the purpose of this paper to discover the factors of economy and to form 
some estimate of their value. 
It is now some thirty-four years since the process began of replacing 
the small individual power plant by electric power obtained from a 
common source of supply. At first the electricity-supply was confined 
within the municipal limits, and the application largely confined to 
lighting, both private and public, the earliest electric stations being de¬ 
signed solely with a view to supplying electricity for street-lighting. As 
the generating plants increased in size and reliability, however, the use of 
electricity for motive power became general, and within ten years of its 
introduction the power business rivalled the lighting business in magnitude 
and importance. 
This still left a large field unprovided-for, comprising all power-users 
located outside municipal areas as well as the larger power-users within 
the several areas of supply, which, as has already been stated, were largely 
confined to municipal boundaries. 
Large municipalities or companies operating in populous districts, and 
owning large plants economically designed and favourably located as regards 
coal and water supply, were able to cope fairly well with the power re¬ 
quirements within their area of supply; but in general the generating plants 
were too small and uneconomical in operation to enable them to supply 
power to advantage in all cases, and it may be said that the self-contained 
power was larger in the aggregate than the power supplied from the common 
source even within the area of supply. This left a large demand for power 
unsatisfied both within and without the municipal boundaries, and some 
fifteen years ago the idea of a supply in bulk over large areas was conceived 
and began to take shape. In Great Britain several Acts were passed 
conferring upon power companies the right to supply local authorities in 
bulk, and, be it noted, also imposing upon them the duty of supplying any 
person requiring a supply of power for motive purposes. The several areas 
of supply defined by these Acts were conterminous with the principal 
industrial districts, as will be evident from their designations, of which the 
following is a selection : the South Wales Power Company ; the Yorkshire 
Power Company; the Lancashire Power Company ; the Midland, the 
Clyde Valley, the Newcastle, the Cleveland and Durham Power Companies ; 
and others of smaller extent. 
The history of electric-power supply has thus passed through two stages : 
first, aggregation of power within the limits of the requirements of a 
municipality; and, secondly, aggregation of power within industrial areas, 
including counties, municipal and other local authorities within the counties. 
A further notable step in the process of aggregation and concentration of 
electric-power production was the amalgamation of two or three power 
companies on the north-east coast of England ; and it is noteworthy that 
4—Science. 
