While it is the common belief that the rotary cylinder gasoline motor is of French origin it may safely be said that this type of motor was in actual use in America for several years before it even reached the experimental stage in Europe. The Adams-Farwell Company of Dubuque, Iowa, were driving automobiles successfully with a rotary cylinder motor before Orville Wright flew at Fort Meyer, Va. Although the original Farwell motor more than proved its right to existence by faithful service under the most exacting conditions, the motor never received the consideration that it deserved, probably because of its great divergence from what is known as “accepted practice.” In Europe no such prejudice existed, and consequently the type made rapid strides, although, to the writer’s belief, the European model is inferior in many ways to the original American type. The fact that this type of motor holds practically all of the world’s aviation records speaks for its practicability in spite of its unusual construction. With the rotary motor, the cylinders and crank case revolve about a stationary crank shaft, the latter part not only serving as a point of reaction of the cylinders but as a support and intake pipe as well. Since the crank throw remains stationary, the cylinders and pistons revolve about two different centers, the cylinders revolving about the crank case and the pistons and connecting rods about the crank pin. Since the pistons, cylinders, and connecting rods must necessarily revolve together, as one unit, there is absolutely no reciprocating motion in regard to the crank shaft except for a very slight movement due to the difference in angularity of the connecting rods. The motion of all the parts is strictly rotary in every sense, except for the relation of the pistons to the cylinders, and the motion is as continuous as in a turbine. This insures freedom from vibration. As the cylinders and crank case have considerable inertia there is no need of the added weight of a fly-wheel. The movement of the piston in the cylinder bore is brought about by the difference in the centers about which these parts revolve. This gives cylinder displacement without the reversal of stresses or shock or jar. Because of the revolving cylinders, the mixture is supplied to the crank case through a hollow shaft, the gas being drawn into the cylinder on the suction stroke through an inlet valve placed in the head of the piston. As a rule, the exhaust is direct to the air through the exhaust valves and without manifolds or mufflers. The motion of the cylinders through the air multiplies the efficiency of the radiating Fins. (55) The Gyro Rotary Motor.