In no other sphere of employment has petroleum made such rapid strides during the past two or three decades as those recorded in connection with its use in internal combustion engines, and one of the most interesting features of modern mechanical engineering is their development. The advent and immediate popularity of this kind of engine has been responsible for some of the most remarkable conquests of mankind over the forces of Nature, for it has brought into being the automobile, the aeroplane, the dirigible airship, and a host of other inventions. It has also been responsible for quite a new departure in ocean transport, for experiments have proved that the largest vessels can be very economically operated by means of the internal combustion engine. It might, by way of introduction, be well to explain for the benefit of the uninitiated, the meaning of the term “Internal combustion engine.” As most of my readers are well aware, the steam, or, rather, to be exact, the highly heated water vapour which drives the steam engine, is supplied from boilers which are heated by the burning of coal, oil fuel, or, sometimes, gas, and such engines might, therefore, be called “external combustion engines,” since the fuel is consumed in apparatus external to the engine proper. Such a term, however, is not in use amongst engineers, and might raise a superior sort of smile if used in their presence. It will be readily seen from the foregoing that a great deal of weight and apparatus of some complication is required before the water vapour which drives the steam engine can even be provided. In the case of the internal combustion engine, the fuel (motor spirit or the heavier oils) is introduced directly into the engine and there vapourized and mixed with air so as to form an explosive mixture, so that all boilers, with the necessarily complicated systems of piping, etc., are done away with. It needs no imagination to understand the enormous saving of weight and space resulting from this elimination of the boiler, and of the room which it would occupy. The latter-day demands for the provision of lighter and yet lighter, as well as space-saving propelling machinery for submarines, airships, aeroplanes, motor-cars, etc., especially during the war, have enormously stimulated the development of the engine which consumes its own fuel, and which is known as the internal combustion engine. A very wide field has thus been opened out for the exercise of the engineer’s ingenuity, and he has availed himself to the full of the opportunities thus created, never failing to rise to the occasion when fresh demands have been made upon him.