During 1934 and 1935, records of approximately 150 definitely local disturbances were obtained on the Benioff seismographs at the Harvard Seismograph Station. Because of a curious concentration in the daytime hours and the few earthquakes reported felt during this interval, an attempt was made to establish criteria by which records of blasts and of local earthquakes might be distinguished from each other. Three, the ratio of the maximum P to the maximum S, the character of the surface waves, and the angle of emergence are discussed. The records of 32 of these disturbances, well recorded on all three Benioff components, are described. It is concluded that, although some of New England's seismic activity is artificial, there is, nevertheless, a greater amount of natural activity than is ordinarily attributed to this region.

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