So successful were the experiments with new types of four-wheel-drive trucks and tractors that orders for what would probably have proven the best type of four-wheel-drive truck and the best type of four-wheel-drive tractor ever produced had been placed, but the signing of the armistice forced cancellations of these orders. In the course of the experiments, all types of American four-wheel-drive vehicles were examined and two of the best French types. The purchase of $365,000,000 worth of trucks, trailers, and tractors was obligated in about 3,000 separate orders. SELF-PROPELLED CATERPILLAR GUN MOUNTS. In Europe, the French had been the only people to experiment with caterpillar mounts for guns. They produced the St. Chamond type, but this had not gone far beyond the experimental stages. Prior to the early months of 1918, our own efforts along this line consisted in the building of one caterpillar mount, self-propelled by a gasoline engine and carrying an antiaircraft gun. Around this nucleus an ambitious caterpillar program was built. An 8-inch howitzer was placed on this antiaircraft caterpillar mount and fired at angles of elevation varying up to 45°. Maneuvered over difficult ground, the machine withstood the firing strains and road tests in a highly satisfactory manner. As a result of the success of these tests, orders were placed for three more experimental caterpillars to mount 8-inch howitzers. Tests of two of these completed units were so gratifying that it was felt they warranted quantity production. Accordingly, orders were placed for 50 units of the 8-inch howitzer caterpillars to cost about $30,000 apiece, for 50 caterpillar units mounting 155-millimeter guns, and for 250 units mounting 240-millimeter howitzers. The Standard Steel Car Co., Hammond, Ind., was to produce the 240-millimeter howitzer caterpillars, the Harrisburg Manufacturing & Boiler Co., Harrisburg, Pa., was to turn out the 8-inch howitzer caterpillars, and the Morgan Engineering Co., of Alliance, Ohio, was to produce the 155-millimeter gun caterpillars. Mountings for the 8-inch howitzer and 155-millimeter gun were practically identical. Both utilized many of the standard Holt caterpillar parts. The only real change was in the carriage for the 155-millimeter gun. This was made sufficiently sturdy to carry higher-powered guns. A 194-millimeter gun is now being machined in France, and when finished it will be shipped to this country to be mounted upon the 155-millimeter caterpillar mount for experiment.