Thus artillery development has gone steadily forward. Every military power has striven with the aid of its best engineers, designers and manufacturers to get a stronger gun, either with or without a heavier projectile, but in every case striving for greater power. As a special development and a not too important one, due to its lack of effectiveness in comparison to its cost, we find the now famous long range gun of the Germans, successfully delivered a projectile approximately 9 inches in diameter into Paris punctually every twenty minutes from a point about 75 miles distant. The Germans used three of these guns in shelling Paris. Their life was probably limited to about 75 rounds due to the excessive demands made upon the materiel. The American Field Artillery Service now has before it four types of field gun carriages, namely our 3” model of 1902; the French 75 M-1897; the British 18 pounder, M-1905 converted to a 75-mm (known as the model of 1917); and our 75-mm model, 1916. There is being produced (1919-20) an improved model of 1916 75-mm carriage on which the St. Chamond pneumatic recuperator, adopted jointly by the American and French governments, will be substituted for the spring recuperators; and the French 75-mm gun will be substituted for our shorter calibered type. From these types one must be selected. An intelligent selection involves a consideration of what may be expected in the future in order that it may best fit in with the new types yet to be evolved. For horsed artillery—and horse artillery will be with us for some years to come—the limiting features of draft and man power will still pertain. For tractor-drawn mobile artillery, the limiting feature is the tractive power of the tractor with relation to the weight of the gun and carriage, the unit being physically limited in weight by the supporting-power of the pontoon bridge which is about 10,000 pounds per vehicle. For Caterpillar Artillery.—By that is meant guns mounted on caterpillar tractors—the limiting features are power and weight, coupled with the weight limitations of the pontoon bridge. To circumvent the question of weight, the load may be divided by mounting the motor by an electric generator on one caterpillar and the gun with an electric motor, on the other, a transmission cable connecting the two vehicles.