oe 
OcTOBER 9, 1913] 
-eonfess himself beaten by the steam locomotive? The 
answer each one of us would give to this question 
must necessarily be biassed by our early training. 
Most engineers love their profession, and are enthu- 
siasts; being enthusiasts, they are necessarily biassed. 
This applies as well to the electrical engineer as to 
the mechanical engineer—perhaps to the electrical 
engineer most. In many cases he is so biassed that 
he will not admit any virtue in any other but his own 
pet scheme of electric traction. A modern steam loco- 
motive is a beautiful and efficient engine, and one can 
well understand its designer looking at it with the 
pride of a father whose son has turned out a good 
man. One can also understand that this engineer 
will not readily admit the superiority of an electric 
locomotive. The mental horizon of each of us must 
necessarily be narrowed by previous training and pro- 
fessional enthusiasm; let us, then, try to forget for a 
moment that we are engineers, and let us put out of 
our minds all questions of mechanical or electrical 
detail, focussing our thoughts merely on what we see 
going on all around us as regards electrification of 
railways. We see year by year more lines being 
electrified. Some are failures; but the very fact that 
in spite of these failures the process of electrification 
is going on, shows that the failures are remediable. 
In some cases it is easy to understand why a line 
should be electrified. If fuel is dear, if the trains 
must be heavy and frequent, if there are steep grades 
and long tunnels, then obviously steam is at a dis- 
advantage and electricity can beat it easily. But the 
electrification is not limited to cases where there are 
such obvious advantages. We see a military State 
like Prussia electrifying a fairly long line where the 
- traffic is not extremely heavy, where there are very 
gentle grades, and only few and short tunnels. More- 
ever, one of the stock arguments against electrification 
is that in case of war the whole system may be broken 
down by the enemy cutting the wires; yet this con- 
sideration, if it has any weight—a matter on which I 
cannot pronounce an opinion—does not deter a mili- 
tary State from at least experimenting with electric 
traction on a large scale. We see suburban lines 
growing longer and longer, until they might almost 
be classed as short main lines, and we see the Swiss 
Government buying up water-powers with the object 
of utilising these powers in the electrification of its 
most important main lines. We see in America the 
electrification of large systems taking place, not only 
for passenger service, but also for the goods service, 
comprising trains of 2000 and more tons weight, and 
of goods yards, to the complete exclusion of steam. 
One need not be an engineer to appreciate the sig- 
nificance of such a general development. No Govern- 
ment department, and certainly no board of railway 
directors, will spend money merely for the sake of an 
interesting scientific experiment, and, although it is 
conceivable that in an isolated case such an experiment 
may be undertaken under a miscalculation as to its 
possible success, it is not conceivable that such a mis- 
calculation should be the general rule. When we see 
that in all countries a vast amount of labour is devoted 
to, and capital is spent on, the electrification of main 
lines, we cannot but come to the conclusion that this 
new application of electricity is bound to progress, and 
that the persons who tell you that electric traction is 
all right for tramways and urban railways, but will 
never be able to compete against steam traction on 
main lines, are very much in the position of my old 
Swiss friend, whose conception of power transmission 
was entirely limited to the use of ropes and pulleys. 
It is just thirty years since the first electric railway 
was opened for public use. That was’a small line 
in Ireland, known as the Portrush-Bushmills Railway. 
NO. 2293, VOL. 92] 
NATURE 
185 
In those days only the continuous-current motor was 
available, and that only at a very moderate pressure 
and power. These restrictions were from the first felt 
to be a serious drawback, and inventors tried to over- 
come them in various ways. Of these, two may be 
here noted, in passing. Ward Leonard in 1891 made 
the suggestion of carrying on the train a converting 
station. He argued, quite correctly, that for the 
transmission of power to long distances the alternat- 
ing current was eminently suitable, and that, conse- 
quently, the power should be sent to the train in the 
shape of high-pressure alternating current. On the 
other hand, such a current was, in those days, quite 
unsuitable for motors; hence the necessity of its con- 
version into continuous current, with which the then 
available motors could alone deal. Ward Leonard 
suggested to put on the first vehicle of the train a, 
synchronous motor, which drives an exciter and con- 
tinuous-current generator. The current obtained from 
this generator was to be used to drive the train- 
motors, which might be distributed in a number of 
motor coaches. The regulation of speed and tractive 
force was to be effected entirely by suitable adjust- 
ment of excitation, and therefore without rheostatic 
loss. It will be admitted that this proposal has some 
attractive features. It is essentially a long-distance 
system, and at the same time it offers the possibility 
of great and uniform acceleration, a matter of great 
importance in urban traffic, so that it is equally suit- 
able for both kinds of service. Moreover, the current 
can be taken with unity-power factor. Unfortunately 
the extra weight which has to be carried in the shape 
of converting machinery is a serious drawback; and 
for this reason the Ward Leonard system. (excellent 
as it has proved in other applications of electric power) 
has in the domain of traction never got beyond the 
experimental stage. 
The experiment has been made on a fairly large 
scale, but with this difference, that the  traction- 
motors were placed not only into motor coaches, but 
on the first vehicle itself, which thus became an elec- 
tromotive; also, in order to save the weight and cost 
of starting and synchronising gear, the asynchronous 
type of single-phase motor was adopted, thus sacrific- 
ing the advantage of unity-power factor. The electro- 
motive developed at the hour-rating 200 horse-power, 
and weighed 46 tons. This is not a very brilliant 
achievement, and it was beaten by a sister engine ot 
the same power, but using alternating-current motors. 
This electromotive weighed only 40 tons. 
It is probable that a better weight efficiency could 
be obtained nowadays with this system if carried out 
on a larger scale, and if the motor-generator were 
replaced by a converter, in which case the step-down 
transformer would have tappings on its secondary 
side for starting and regulation. It is, however, 
doubtful whether even then it could compete with 
electromotives using the alternating current in the 
motors directly. Motors of this type have recently 
been so much improved that the margin of weight 
that could be saved by the use of continuous-current 
motors is probably less than the excess weight of the 
converting machine. 
The other attempt to combine high trolley-voltage 
with low motor-voltage has shared the same fate. 
This consisted in the application of the three-wire 
principle of continuous-current supply to electric trac- 
tion. It is in successful operation at a moderate 
voltage on a London tube railway, but as far as 
main-line working is concerned it has not got beyond 
an application on two small lines in Bohemia. The 
principle adopted is to make the trolley wire of the 
up-line the positive and that of the down-line the 
negative side of the system, whilst the rails take the 
