ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. Each 

 of the scientific bureaus in Washington has a representative authorized to for- 

 ward such material to this journal and abstracts of official publications should 

 be transmitted through the representative of the bureau in which they originate. 

 The abstracts should conform in length and general style to those appearing in 

 this issue. 



METEOROLOGY. — Waves of pressure in the atmosphere recorded by an 

 interferometer barograph. Albert C. Crehore and George 0. 

 Squire. Bulletin of the Mount Weather Observatory, 4: 115-118. 

 1911. 



In addition to the large changes in atmospheric pressure that are indi- 

 cated by every barometer, there are numerous minute and rapid fluctua- 

 tions that are neither recorded nor shown by any ordinary barometer, 

 whether mercurial or aneroid. 



Several methods have been developed, however, for showing and 

 recording these minute and often nearly rhythmical changes in atmos- 

 pheric pressure ; but the one under review probably is the most exact and 

 delicate of all. 



It consists essentially of a vertical pile of aneroid cells capped by a 

 silvered flat that, with change of pressure, correspondingly changes its 

 distance from a fixed half -silvered surface. 



When properly supplied with monochromatic light the resulting inter- 

 ference rings are almost constantly in motion, first in one direction and 

 then the other, in quick and delicate response to every pressure change. 



By the aid of a slit across the interference rings, a camera, and a uni- 

 formly moving film, the pressure changes can be permanently recorded: 

 — -the negatives and the prints they yield looking like ribbons of 

 watered silk. W. J. Humphreys. 



TERRESTRIAL MAGNETISM.— Distribution of the magnetic declin- 

 ation in the United States for January 1, 1910. R. L. Faris, Coast 

 and Geodetic Survey. Special Publication No. 9, pp. 14, with 1 

 map. 

 This publication just issued by the Coast and Geodetic Survey con- 

 tains secular change tables of the magnetic declination and a magnetic 

 declination chart of the United States for the year 1910. On the chart 

 are also shown the lines of equal annual change of the magnetic declina- 



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