NATIONAL I~UREAU OF STANDARDS NOTES.
' 3II movement of this diaphragm causes fluctuations in the output of the pick-up coil. The action is similar to that of the device used as a phonograph pick-up. With a slight modification, the device may be used as a thermometer. A strip of bi-metal of convenient length is so mounted that it extends in a path parallel to the end plane of the pick-up coil, positioned closely adjacent to that coil. As the bi-metal bar bends in accordance with heat, its free end is brought closer to or farther from the pick-up coil and an indication is given on a meter calibrated in degrees.
Another application of the device is the tachometer or speed indicator. In this case, the end plate of a flyball governor may be so mounted as to approach or recede from the pick-up coil as the speed of rotation of the governor increases or decreases. Still other applications of the electronic micrometer are feasible. It is obvious that it can be appleid to any use where the variation in distance between the coil and a conductive plate may be used to produce an electric current which will vary in linear manner in accordance with the change in distance.