In the British army, trucks work in units of about ten, each such unit being commanded by an officer who travels in a fast automobile. Protection, when necessary, is temporarily assigned to the unit, nearly always in the shape of armored motor cars. The trucks are heavily manned, having from three to six men per truck. Every man is armed with a rifle, but no other arms are carried as an integral part of the unit. Such motor transport units are not often captured or destroyed since they seldom come in touch with anything but the enemy's cavalry which, as a rule, prefers to leave them strictly alone, as a train of motor trucks has good defensive ability and none of the vulnerability of horse-drawn wagons. In the rare cases when actions have taken place, motor trucks have become moving forts, which continue on their way at a rate of twenty or twenty-five miles an hour, while from each one three or four well-protected riflemen keep up a steady fire. The type of automobile most desirable for army use has become well-defined. The practice in this regard is the same in the French, British, German, Austrian, and Hungarian armies. On a powerful chassis, with an engine of at least 50-horse-power, is mounted a very light body, of the "pony tonneau" type, with room for two men in front and two behind. The equipment consists of a folding top, leather or isinglass wind-shield, powerful head-lights, the noisiest horn obtainable, and racks to carry as much extra gasoline as possible. In service these automobiles have big racks full of gasoline-cans carried on the running boards and at the rear and, in addition, there are often necklaces of two-gallon cans strung wherever possible. In virtually all the armies gasoline is served out in small cans containing about two gallons each, which are easily handled and quickly stored. One or two may be put in any odd space which is not otherwise in use. This method is very effective and is one of the most important developments in military automobile practice. In none of the armies are cars used which vary greatly from the type above mentioned, except through necessity. In general, heavy cars and runabouts give very inferior service. It is the general custom for the chauffeur and an orderly to ride on the front seat, and one or two officers behind. The more speed the machine develops the better. It is not uncommon to see staff officers or generals traveling over the French roads at a speed of one hundred kilometers an hour. There is quite a well-defined tendency to have as drivers men who are well above the average. In the French army these men are usually sergeants or lieutenants; in the Austrian army many of them are lieutenants. Corps and army commanders usually have big, heavy limousines, with electric lighting, which they can, when necessary, use as offices, or as headquarters. SIGNAL CORPS