424 
MR. LOUIS VESSOT KING ON THE SCATTERING AND 
Diagraini I .—Variation of Coefficients of Atmospheric Attenuation with JVave-Lencith. 
The curves of Diagram I. are drawn from the data given in Table 1. The coefficients of attenuation 
at the various stations are plotted against the inverse fourth power of the wave-lengths, the wave-lengths A 
l^eing expressed in microns. The observations give rise to a law of the form 
C^=-/3X~^ + y. 
The stations to which the various lines refer are as follows :— 
Curve 1. Mount Whitney. Curve III. Potsdam. 
Curve II. Mount Wilson. Curve IV. M'^ashington. 
The conclusions derived from these observations are descril^ed in Section 7, and the constants of 
atmospheric scattering and absorption derived from similar curves plotted on a large scale are given in 
Table II. 
The discontinuity in the curves in the neighbourhood of ’GlOp at low-level stations is clearly marked, 
and the observations show that the curves may be represented by broken straight lines. We cannot 
suppose, however, that the discontinuity at A = -GlOp will in reality be as sharjj as tlie intersection of 
two straight lines would require. The j^recise cause of this well-marked point of discontinuity furnishes 
a point which must l)e left to further investigation. 
