L. A. Bauer— Variation of Terrestrial Magnetism. 115 
To show that the empirical laws are identical, I have plotted 
the mean quantities for the interval 1780 to 1885, as taken from 
Tables I and II on the accompanying diagram. The inclination 
curves have been inverted. The distribution curves and the 
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secular variation curves are found to run parallel courses. We 
are thus forced once more to our former conclusion, viz: 
that the distribution and the secular variation are intimately 
connected ; they obey similar laws and will hence wm all proba- 
bility have to be weferred primarily to the same cause. 
Washington City, June 2. 
. 
