MOTORCYCLES. Although the motorcycle did not be come popular in any country until 1911-12, the first examples of it were seen in France and Germany about 1885. In 1907, the first of a series of famous motorcycle road races, the International Tourist Trophy races, was held in the Isle of Man. The im portance of winning this race urged designers to improve their machines, as regards both speed and reliability, and from then until 1914, the first year of the World War, the production of motorcycles increased by leaps and bounds. The necessity for the manufacture of war materials, and the difficulty of obtaining petrol then reduced the combatant countries' production of motor cycles to a minimum, but in America an increasing number of machines were made. There was a tremendous demand for motor cycles in the years 1919-20, but British manufacturers, disor ganized by war work, were unable to meet it. In 1919 America sold 1,481 motorcycles to Great Britain, and in 1920, The numbers then dropped until, in 1926, they reached the low figure of 75, whereas in the same year 48,391 motorcycles were exported by Great Britain and 628,955 were registered for use in that country. The production of motorcycles in various countries for the year 1933 was as follows:— Germany 52,707 United Kingdom 52,205 France 36,307 Italy 12,500 U S A 7,377 Belgium • • Stages in Improvements.—The advance in the motorcycle's utility can be marked by three distinct steps. The first was the discovery that the best position for the engine was in the centre of the frame, rather nearer the front wheel than the back, and the adoption of this fixing; the second was the advent of elec trical ignition ; and the third was the use of efficient chain trans mission through a change-speed gear-box. Many other improve ments, such as those relating to carburization, frame design, etc., were effected, but the three mentioned above were outstanding in the resultant popularity of the motorcycle. There was no definite position in which one might expect to find the 19th cen tury motorcycle's engine. On some machines it was carried in front of the steering head and drove the front wheel; on others it was attached to the down tube from the steering head, being either in front of or behind it ; the seat pillar tube, again, some times carried it, whilst on a few machines the power unit was built up into the back wheel or placed immediately above it. In all
except the first position mentioned the power was transmitted to the rear wheel. Early in the present century it became acknow ledged that the most suitable position for the engine was low down in the frame, just in front of the pedalling gear. In most cases the crank-case of the engine was bolted into the frame, and thus formed part of it, but on a few machines and notably the Ameri can "Indian" the down tube from the steering head was continued below the engine. This pattern was known as a loop frame, and although it was little in evidence for many years it is to be found in an improved form on many modern machines.
The problem of ignition of the petrol vapour was one which had puzzled designers from the earliest days of the internal com bustion engine. The first form of ignition consisted of a tube protruding from the cylinder, the rider having to heat its external end by means of a Bunsen burner using petrol fuel, before the engine could be started. Towards the end of the nineteenth cen tury, this system, which was known as "tube ignition," was re placed by electrical ignition, composed of a battery, coil, contact breaker and sparking plug. The first electrical system was greatly in advance of tube ignition, but in its early form it was by no means trouble-free, and it was not until the advent in 1903-04 of the magneto, an instrument which generated current when it was rotated, that the motorcycle became a practicable means of transport. Until then the machine as a whole was extremely unreliable, and the rider could never be sure of concluding a run under the power of his own engine. Even when the magneto had marked a reasonable degree of reliability, the motorcycle was still suitable for young and active men only, owing to the inade quacy of its transmission system.