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other can be readily foUowed by simple inspection. There are no missing lines at the center of the band. Preliminary data have been obtained in five other regions of absorption shown in Coblentz' curves. In some of these the measurements have progressed quite far but they will not be discussed at present, for it is desired to repeat them and possibly increase their refinement by improvements in some parts of the apparatus.

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In an attempt to determine the amplitude of vibration of the ions in a quartz lattice brought about by piezoelectric oscillations, a series of Laue photographs have been made of both Curie and thirty-degree-cut plates, using the white radiation from a Coolidge universal tube. This tube had a tungsten anode and carried a current of four milliamperes at 95 kilovolts. Eastman duplitized x-ray film was used with no sensitizing screens. On examination, the patterns produced by each plate, oscillating and non-oscillating, appear identical except in one respect; the pattern of the oscillating plate is several times as intense as that of the non-oscillating. A four-hour exposure of a non-oscillating plate to radiation of the above mentioned type, produces but the rudiments of a pattern, whereas, the same plate oscillating produces a very beautiful intense pattern for the same time of exposure. The effect does not depend on the mode of vibration but does depend on the amplitude. Further work is in progress which it is hoped will establish the cause of this peculiar intensity difference.

The piezoelectric properties of quartz and tourmaline have been investigated through a study of the converse piezoelectric effect. In the case of quartz, the piezoelectric constant has been measured from point to point across the specimen. Considerable variation in the ``constant'' has been observed in different samples of quartz. Attention is called to difference between the motions of piezoelectric plates when subjected to static electric fields and when subjected to alternating electric fields.