A MORE accurate control may be gained over a strand motor by using gear wheels. Both their speed and duration may be increased indefinitely. The gear will restrain a powerful motor from "racing," acting much the same as the governor of an ordinary engine. Still another advantage is the steadiness they insure to a machine in flight by cutting down the vibration. The geared wheels and the frames for mounting them will be found to add very little weight, and they make possible a saving of rubber in the motor which renders such equipment no heavier than the ordinary direct-drive motor. Gears may be installed upon any ordinary motor base. Here is a fascinating field for experiment. The great advantage of the geared motor lies, of course, in the fact that it enables you to divide up your rubber motor into smaller groups of strands. As you increase the power by adding more rubber, you of course cut down the number of the turns it will take. A motor forty inches in length, comprising six strands of rubber, one-eighth of an inch square, may be twisted to about one thousand turns. Double the number of strands and you will find that you cannot get more than five hundred turns with safety. Double the diameter of your motor one more and it cannot be twisted more than to two hundred times. Now it is clear that if the motor consists of two groups of six strands each, and the axles be geared together, it may be wound up with one thousand turns while the power exerted will be that of the twelve strands. A motor with three groups of strands in turn will give you one thousand turns with the propelling force of the combined number, or eighteen strands, and so on. As a general rule, it may be laid down, that by dividing your motor you double the number of revolutions. The heavier the motor the greater is the vibration in unwinding, and as you have doubtless discovered, a model which vibrates in flight offers a greatly increased resistance to the air. The geared motor cuts the vibration in half, or a third, as the case may be. Incidentally, this renders your motor practically noiseless. The resistance offered by a set of smoothly-running geared wheels is slight, and may be compensated by adding more strands to the motor. In mounting them use the same care as used in the shafts of ordinary motors. By mounting them on a simple metal frame the friction may be cut down still further. This mechanism, moreover, is so slight that you can afford to select substantial material for the purpose. The clock wheels used in most of our American clocks are too thin for the purpose and easily slip apart.