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Rh that they really have no history. Although Daimler designed a motor bicycle in 1885, it was not till five or six years ago that serious and sustained efforts were made to perfect the petrol motor bicycle. In this connection the Wulfmuller was a pioneer. It had a double-cylinder motor, driving the hind wheel, and was a cumbersome and unsuccessful machine. The Werner occupies a similar position among motor bicycles to the De Dion among motor tricycles. While gear driving has been universally adopted in the latter, most of the motor bicycles have been adapted for belt driving. One—that invented by Lieut.-Col. Holden—has dispensed with both, and has the novel feature of a four-cylindered engine, from which the motion is transmitted to cranks on the back wheel by means of connecting-rods. The Holden has another point of difference from the common practice in the fact that the cylinders of the engine are water-jacketed, while air-cooled motors are almost universally employed on motor bicycles.

The first point of interest in connection with motor bicycles is the position of the engine, and owing to the practice, in the early Werner machines, where the motor was fixed above the front wheel, it was long thought that the weight of the engine should be placed as high upon the bicycle as possible. That location, it was claimed, was necessary to ensure the stability of the machine, and to minimise the danger of side-slip. Experience, however, has shown that this is not so essential, and there are now a score or more of motor bicycles only two of which have the engine above the wheels. In the latest type of Werner the engine is placed halfway between the two wheels in a vertical position, thus bringing the centre of gravity very low. A low-down position between the wheels is being generally adopted, as tending to reduce the vibration and lessen the liability to side-slip.

The subject of side-slip is one of the greatest interest to all motor cyclists, and the position of the motor has been variously located, with a view of minimising its occurrence. It is generally acknowledged that motor bicycles are more prone to