May 16, 1912] 
been electrified. The total 
amounts to nearly 200,000. 
It is obvious that an undertaking of these vast 
dimensions, covering as it does large portions of two 
counties and several large towns and _ industrial 
centres, could never have been undertaken by a single 
municipality. It is equally obvious that it could never 
have succeeded as well as it has had Newcastle itself, 
which has been from the first the nucleus of the 
undertaking, been cut out of the area of supply. 
This explains why other electric power schemes, such 
as those being worked on the Clyde and in the area 
round Glasgow, in Yorkshire and in Lancashire, have 
failed to go ahead anything like so rapidly as the 
one of which I have just been speaking. Parlia- 
ment in its wisdom, at the instance of municipal 
parochialism, cut nearly all the large towns out of the 
areas supplied by these schemes, with the result that 
progress has been impeded with real benefit to no one. 
As to the future, we have seen from the lessons of 
the past how very dangerous it is to prophesy, it being 
frequently the entirely unexpected that turns up. So 
far as the immediate future of electricity generation 
on a farge scale is concerned, the steam turbine 
appears likely to hold the field, though in regard to 
the smaller stations, where units up to 500 or 1000 
kilowatts are what are wanted, the internal-combus- 
tion engine is undoubtedly gaining ground. Will it, 
however, ever catch up the steam turbine in the case 
of the really large power stations? Turbine units up 
to 25,000 kilowatts are now in actual use or in con- 
templation, and as electricity becomes more and more 
employed, not only for power, but for electrochemical 
and metallurgical purposes and for domestic heating, 
we may expect units of plant of still larger dimen- 
sions. At present about 2000 horse-power, or about 
1500 kilowatts, seems to be about the maximum that 
it is considered can be safely obtained per cylinder from 
the internal-combustion engine, so that increased 
powers can only be obtained by a process of multipli- 
cation, which leads, in the case of very large units of 
plant, to great complication. Then again, as the 
steam turbine, particularly with the employment of 
superheated steam, tends to increase in fuel economy 
as the dimensions of the unit of plant are increased at 
a much greater ratio than does the internal-combus- 
tion engine, a point must be reached when, as we 
enlarge the units of plant, taking all things, such as 
first cost, lubricating oil, attendance, and upkeep, into 
account, the steam turbine will be as cheap as, or 
even cheaper than, its rival. 
So far, the internal-combustion or gas turbine has 
not been alluded to, but some of the difficulties in the 
way of its successful realisation may be mentioned. 
All turbines essentially consist of machines by means 
of which power is obtained by the passage of fluids or 
hot gases through narrow apertures, and by their 
impingement on blades, in such a manner that the 
fluids or gases are in intimate contact with large 
surfaces of metal. Now, as all engineers are aware, 
the law which limits the efficiency obtainable in any 
heat engine is expressed by the formula (T’—T)+T’, 
where T’ is the absolute temperature of the working 
gas and T the absolute temperature of the condenser 
or the exhaust. From this it is clear that if we are 
to get maximum efficiencies, the temperature of the 
working fluid must be as high as possible, and the 
sole reason for the extra good efficiency of an internal- 
combustion engine is because in this machine the 
temperatures that can be successfully dealt with are 
very high. In the cylinder the combustion takes place 
when the gas is in considerable mass, and though 
those portions of it which are in contact with the 
NO, 2220, VOL. 89] 
horse-power connected 
NATURE 
283 
walls of the cylinder become cooled, still, the interior 
of the mass keeps very hot, indeed at temperatures 
which could not possibly be employed in turbines 
unless we could find the materials of which to con- 
struct the blades which would maintain their tenacity 
while running at a red heat. It is conceivable that 
the science of metallurgy may be able to provide new 
metals or alloys with the necessary properties for 
doing this in the future, but at present no such 
material exists, and the only way in which the 
internal-combustion turbine can for the moment be 
worked is by reducing the temperatures of the gases 
by the introduction of water, steam, or air to a reason- 
able amount; indeed, in practice the temperature has 
to be reduced to that usual with superheated steam, 
when, of course, according to the formula I have 
quoted, the maximum efficiencies theoretically obtain- 
able with the internal-combustion engine and the 
steam turbine become equal. Even then, if other 
things were equal, the internal-combustion turbine 
might have some advantage by doing away with 
boilers; but, unfortunately, there are other difficulties 
—such as the bad economy of all methods of compress- 
ing the gaseous mixture as is necessary to obtain the 
full advantage of its combustion. 
No doubt the future of electricity supply lies with 
very large stations employing very big units of plant, 
and combining the generation of electricity with 
chemical manufacture, the electricity on the one hand 
and the chemicals on the other being by-products each 
of the other’s manufacture. So far as this country is 
concerned, for electricity supply at all events, we are 
not likely to depart from the use of coal so long as 
that source of energy holds out. For the propulsion 
of ships oil may present advantages, but on land in 
Great Britain coal must remain the cheaper. In all 
probability, however, in the future the coal will not 
be simply burnt. It will be turned into gas, 
and the sulphate of ammonia and_ the tar, 
with all its interesting constituents, saved. 
| Whether the gas will be burnt under boilers for the 
_ raising of steam to supply steam turbines, or whether 
it will be used in internal-combustion engines, will 
depend on the progress made by the latter in regard 
to attaining larger dimensions, and also as regards 
improvements in the gas firing of boilers, in respect 
of which, as has recently been shown by Prof. Bone 
| in his interesting lecture on surface combustion, there 
| is still much to be done. 
| of the demand for power, 
When the coal and oil and also the peat are ex- 
hausted, what then? The date may be distant, but 
come it must, and that within a period short in com- 
parison with our past civilisation. 
The water-power existing on the earth, when all 
harnessed, would only supply a very small percentage 
; light, and heat. The 
utilisation ot the tides does not appear a very hopeful 
project, any more than does the utilisation of the 
internal heat of the earth. There remain the energy 
| dependent on atomic transformation, the availability of 
which the highest authorities appear to regard as 
probably impracticable, and the radiant energy that 
reaches this planet from the sun. The latter, as calcu- 
lated by Sir J. J. Thomson, amounts on a clear day 
to no less than 7000 horse-power per acre, or about 
4,500,000 horse-power per square mile of the earth’s 
surface. 
Here is obviously an ample supply of energy 
sufficient for all purposes provided it can be converted 
into work by some reasonably efficient process. This 
should not prove impossible, and we have therefore 
here a problem for the physicist of the utmost import- 
ance to the race. 
