[Illustration: _“The Autocar” photograph._ A FRENCH PETROL-ELECTRIC FOUR-WHEEL-DRIVE TRACTOR, THE WHEELS OF WHICH ARE SPECIALLY SHOD TO FACILITATE TRAVELLING OVER ROUGH GROUND.] In the brief sketch already given of the principal trials and manoeuvres in which motor transport has figured, some indication has been afforded of the attempts made by the British Government in this direction. The most consistent, and probably the most successful, efforts have however been made by our neighbours, the French, who have for this special purpose given much encouragement to the development of internal combustion tractors driving all four wheels. The movement dates back about three years, and owes its origin to the need for hauling 155 m/m siege guns along roads and across country. The first type of tractor produced to meet the requirement was the Chatillon-Panhard. The weight of the first type with full load was in the neighbourhood of 22 tons, and more recently efforts have been made to evolve lighter types weighing about 14 tons with their load, the belief being that these rather smaller machines would be of great general utility. Some very important trials in this connection took place in France early in 1914, four types of tractor participating, namely, the Latil, the Schneider, the Chatillon-Panhard and the Renault. The first-named is a development of the Latil type of lorry, in which the engines drive the front wheels, and the whole power plant is concentrated on to the fore carriage, the back wheels and the platform being really nothing more in principle than a two-wheeled trailing vehicle. An extension of this system involves the use of three differential gears, one for each pair of wheels, and a third as a balance gear half way along the vehicle from which the drive is taken fore and aft through longitudinal shafts and worm gearing. All four wheels are steered as well as driven.