1918.] The N.Z. Journal of Science and Technology. 211 
and the amount of the load are not always proportional to the amount of 
-energy with which their values are proclaimed. 
To obviate these difficulties, and endeavour so to design the power-supply 
system as to serve the whole country to the best advantage and in such 
way that it would become self-supporting in the least possible time, it-was 
necessary to get an accurate general view of the markets to show at the 
same time both their value and their location. The ordinary industrial 
power and lighting load is proportional to the population, so that a census 
of the population gives some idea of the value of the load that is to be 
obtained when power is available. This may be not quite true of special 
large-power users, such as chemical and metallurgical works, &c.; but 
these are few and small at present, and can be considered specially in rela¬ 
tion to the system. Afterwards new industries as they develop will locate 
themselves where power is cheap, which, other things being equal, is close 
to the source of power or to existing transmission-lines. As water-power 
development always involves a large capital expenditure, the first few 
years of their operation, while the load and consequent revenue are growing, 
are always the most critical. It is therefore essential that the districts 
first to be supplied should be those in which the market already exists, 
and the source to be developed is the one, or more, that will serve those 
districts as a whole most economically. This gives existing markets a 
value much in excess of those that are only prospective. 
For this purpose the maps which are attached have been prepared, 
showing the distribution of population, and consequent prospective im¬ 
mediate power load throughout the Dominion. It is not the purpose of 
this paper to describe the system of electric supply proposed, but as the 
maps have a certain amount of general interest apart from the special 
purpose for which they were compiled it is proposed to reproduce and 
briefly described them here. 
It was not possible to reproduce on the small scale of the maps printed 
herewith the same system of shading as was adopted on the original maps, 
which were on the 16-miles-to-l-inch scale, and a scheme of colouring has 
been substituted. The population statistics published in the New Zealand 
Official Year-book, 1917, have been taken as a basis, and from the figures 
given for population and county area the population-density per square mile 
has been calculated. The counties have then been divided into classes, the 
population-density of which is fixed within the limits shown on the maps. 
So also for the principal towns, the population of which is not included in 
the surrounding counties, a series of signs has been adopted fixing the towns 
into classes which have the limits of population shown on the map. 
The distribution, of course, in some cases varies considerably over 
different parts of the same county, and some improvement might be made 
by taking smaller subdivisions in arriving at the averages. As, however, 
we now have the location and size of the towns and the densitv of the 
«/ 
county population all under the eye at once, we get a very good idea of 
the general distribution of population throughout the country. 
In the original maps, which were compiled on larger scale, the county- 
population density was shown by a system of shading which was inversely 
proportionate to the population-density, and which could be scaled directly 
to give the density per square mile, while the towns were represented by 
circles the area of which was proportionate to the population. These maps 
have been most useful in the particular investigation for which they were 
compiled, and it is hoped that by publishing the modification of them herein 
they may be of value and of general interest to readers of this journal. 
