G.— ENGINEERING. 167 
to-day. ‘This is very largely the result of endless laboratory research 
and experiment. 
The last method of propulsion that I can deal with is that by means 
of the internal-combustion engine. This, as we almost universally have 
it to-day, is the result of the cycle adopted by N. A. Otto in his gas-engine 
in 1876. Here again the engines we have to-day are the result of careful 
and studied investigation. It may be truly said that the advance made 
has been so much more rapid than in the case of the steam-engine and 
electrical machinery because of the more advanced state of scientific 
knowledge, and it furnishes an example of the assistance which this 
gives to progress. 
In relation to transport the work has proceeded on two distinct lines, 
the Daimler and the Diesel engines. In 1885 Gottlieb Daimler produced 
the engine that is associated with his name, and which utilises a light 
spirit which supplies a carburetted air for the explosive mixture for the 
cylinder. The development of this engine has itself proceeded in two 
directions. In the one it has been made very much more flexible and 
silent in its adaptation to motor-car work, whilst in the other the great 
desideratum has been lightness and in association with the improvements 
in the necessary materials has rendered possible the aeroplane as we 
have it to-day. In both cases the development to the degree reached 
has been due to a careful study primarily of the pressures, compression, 
and composition of the mixture. 
The Diesel engine was invented in 1894 by Rudolph Diesel, and 
consists of the injection of oil or pulverised fuel into the engine cylinder. 
Its development has taken place both on the four- and two-stroke cycle, 
and although considerable progress has been made with land engines, 
it has chiefly been used for marine transport. 
The internal-combustion engine has not been largely used for rail 
transport owing to its comparatively high cost of fuel per horse-power 
and its lack of flexibility. The latter is particularly the case when one 
remembers the high torque which is so desirable, and which can be 
attained in both the steam and electric locomotives in starting. 
Throughout these remarks on methods of propulsion I have dealt 
with the points connecting them with rail transport as they occurred, 
as this is not only the method with which I am most familiar, but is the 
oldest means of using mechanical power. I must, however, say a few 
words as regards transport by sea, road, and air in connection with 
methods of propulsion. 
T have already spoken of the early efforts of Hulls, and it was only 
natural that the work of Watt on land should be followed by application 
of the new power available to propulsion on the water. Although the 
growth after the work of Symington, Fulton, and Bell may have seemed 
to be slow, it was continuous, and constant experiments and research 
were made both in marine engines and in their application. Saving of 
fuel has played a much more important part here than with the loco- 
motive, whilst, more space being available and greater power required, 
the advantages of the expansion of steam were rendered more imperative 
and had greater scope than in the other long-established method of 
mechanical transport. The great advance came with the turbine, and 
it is interesting to notice that whereas in early days engines were geared 
