Many advantages are pointed out for the portable cathode-ray oscillograph combined with an electrical vibration pickup for general vibration study. Representative types chosen from the three principal classes of vibration pickups (displacement, velocity, and acceleration) are described. The particular uses for these several types of pickup and their assembly with oscillographs and amplifiers are described as well as experimental methods for determining frequency and phase.

The paper concludes with a description of the use of this assembled apparatus in the following four vibration problems: detection of out-of-round journals and other extraneous causes of vibration when balancing large machines; comparison of the residual sources of vibration in well-balanced ball-bearing high-speed motors; measurement of commutator roughness; and the investigation of high-frequency noise in small single-phase motors.

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