OVERVIEW

Having determined by means of the Component-Recorder the resistance that must be overcome in moving a material plane horizontally through the air at different speeds, the next step of my investigation has consisted in devising means for measuring the power that must be put out by a motor in doing this useful work; for, by any form of aerial propulsion, the useful work that can be derived from the motor is only a percentage, either large or small, of that which is expended. It becomes important, therefore, to determine the ratio between the propelling force obtained, and the amount of power that must be expended in any given case.

In devising the following apparatus I have confined my attention to aerial propellers for reasons of present convenience, and not because I think them the only practicable method of propulsion, although they are undoubtedly a most important one.

If we consider the actual circumstances of such experiments, where the motor under investigation is mounted at the extremity of the large turn-table arm and is in motion, frequently at a rate of over a mile a minute, and that the end of this slender arm is 30 feet from any solid support where an observer might be stationed, it will be seen that the need of noting at every moment the action of apparatus, which under such circumstances is inaccessible, imposes a difficult mechanical problem. After trying and dismissing other plans, it became evident that a purely automatic registry must...