42 
The N.Z. Journal of Science and Technology. 
[Mar. 
users at about 10 to 12 tons of coal per horse-power-year, was thus approximately the 
total amount of the present consumption of the Dominion. Of course, a large con¬ 
sumption must still be required for gas-generating, bunkering, and main-line railways ; 
but, on the other hand, the electric supply would be largely required for new houses 
and new industries, and would also be largely used to replace candles, kerosene, petrol, 
and mainly firewood, as well as coal, leaving a fairly large demand for coal even when 
the full 240,000 horse-power is available from hydro-electric sources. As to future 
developments, the total recorded hydro-electric-power sources of 1,000 horse-power or 
over in the Dominion as recorded in the Year-book of 1914 are between 3,000,000 and 
4,000,000 horse-power, apart from probably another 1,000,000 horse-power available 
in small units below 1,000 horse-power. As to the demand, the provision of one horse¬ 
power per five head of population was, of course, only a stage in the development, 
winch would ultimately be exceeded, possibly many times over. 
Some New Zealand Mineral Oils, by Professor T. H. Easterfield and 
N. McLelland. 
Abstract. 
A statement was given of the districts in New Zealand in which mineral oils had been 
found, and the paper also alluded to the attempts to supply mineral oil by the distilla¬ 
tion of oil-shales at Orepuki, Southland. The sulphur content of the southern shales 
w^as stated to be a very serious objection, and a comparison was given of the properties 
of Taranaki and Kotuku oil. • The former is said to be remarkable in the high content 
of benzoles and cycloparaffins. The proportion of toluol, used in the manufacture of 
T.N.T. explosive particularly, was higher than in the case of the light oil from coal- 
tar. A number of pure chemical compounds taken from Taranaki petroleums w^ere 
exhibited. 
Professor Easterfield stated that, in his opinion, the boring of new wells in Taranaki 
promised at present greater success than development in any other area, but urged 
that as a matter of Imperial interest systematic prospecting by bores should be carried 
out in a number of areas. 
The Quantum Theory, by Professor P. W. Robertson. 
The Horizontal Pendulum, by Dr. C. E. Adams. 
The Wet Process of recovering Mercury from Cinnabar, by W. Donovan. 
Discussion on Isotopes in New Zealand Minerals. 
At a joint meeting of the Physics and Geology Sections Professor P. W. 
Robertson introduced the subject by explaining the recent developments in 
chemistry which had shown that certain elements were mixtures of isotopes, 
while others were suspected to be mixtures. It would be useful to place 
on record the occurrences of New Zealand minerals which were available 
as sources of these suspected mixtures, in order that chemists might know 
where to turn for material. The subsequent investigations might prove to 
have fundamental geological significance. 
After some discussion it was resolved to set up a committee (see 
“ Resolutions,” below). 
The Transit Micrometer, by Dr. C. E. Adams. 
GENERAL SECTION. 
Presidential Address : Science and the Principle of the Relativity of 
Motion, by E. Miller. 
Abstract. 
The aim of the address is not to give an adequate account of Einstein’s theory of 
relativity, but to pick out therefrom certain features which should serve to fit the subject 
on to familiar scientific conceptions, and thereby render the most important results 
of the theory intelligible, perhaps even acceptable, to the non-specialist. The meta¬ 
physical notion of void space involves the relativity of all positions, directions, and 
motions, including rest, or zero motion. But the scientific conception of space has 
