SCIENCE AND INDUSTRY. 
in thickness, and were worked by enormous open-cast mines. The 
whole of the power for the working of the coal was supplied by electricity 
generated on the spot, the brown coal being used as fuel. The coal con- 
tained not less than 60 per cent. of moisture when mined. At one mine 
—Fortuna—8,000 tons were raised daily. About one-quarter of this 
was powdered and dried, so that the water percentage was reduced from 
60 to 16 per cent., and the powder was then made up in “ briquettes,” 
under a pressure of 21,000 lbs. to the square inch. Under this great 
pressure the material became hot and plastic, and sufficient pitch was 
sweated out to cement the block together and prevent it from re-absorbing 
moisture. Of the remaining three-quarters one third was generally 
distributed locally in a raw state for household fuel purposes, and the 
remainder was used in generating electric power for transmission to the 
vast munition works at Essen, over 50 miles distant. The development 
of the brown coal industry, he said, was largely on account of the war. 
In addition to Essen, large factories at Dusseldorf, and in the area 
between Cologne, Bonn, and Duren, were all driven by the electric power 
generated at the mines. As much as 120,000 continuous kilowatts were 
generated at a single mine. He had marvelled at the beautiful and 
colossal generating machinery these mines possessed. One motor he 
had seen was probably the largest in the world; it was a direct turbine- 
driven generator, developing 50,000 continuous kilowatts. He had 
also seen several sets which generated 30,000 kilowatts apiece. 
FUTURE SOURCES OF POWER. 
Considerable interest has been aroused by the speculation indulged in 
by Sir Charles Parsons, in his presidential address to the British Asso- 
ciation at its recent conference at Bournemouth, regarding the future 
sources of power. The passage which has evoked most comment in scien- 
tific circles reads, “ The nations who have exerted the most influence in 
the war have been those who haye developed to the greatest extent their 
resources, their manufactures, and their commerce. As in the war so 
in the civilization of mankind. But, viewing the present trend of 
developments in harnessing water power and using up the fuel resources 
of the world for the use and convenience of man, one cannot but realize 
that, failing new and unexpected discoveries in science, such as the 
harnessing of the latent atomic and molecular energy in matter, as 
foreshadowed by Clerk Maxwell, Kelvin, Rutherford, and others, the 
great position of England cannot be maintained for an indefinite period. 
At some time more or less remote—long before the exhaustion of our 
coal—the population will gradually migrate to those countries where 
the natural sources of energy are the most abundant.” It is estimated 
that Great Britain possesses only 24 per cent. of the coal still available 
to the world, and, in addition, that country is extracting and using her 
coal at a much bigger rate than most of the other countries concerned. 
UTILIZATION OF EARTH'S HEAT. 
In 1904 Sir Charles Parsons put forward the suggestion that borings 
should be sunk in the earth to sufficient depth to enable industry to 
make use of the heat existing below the earth’s surface, and the large 
volumes of high-pressure steam generated there. He then suggested 
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