317 



it seemed desirable to institute a similar inquiry based upon other 

 data and partly other stations. 



For this purpose daily observations made at 7 a.m. as published 

 in diflferent weather bulletins and inscribed in registers at de Bilt, 

 were chosen. 



A first group of stations is: 1. de Bilt, 2. He d'Aix (W. coast 

 France), 3. Dresden, 4. Lerwick (Shetland Isles). The distances between 

 de Bilt and the surrounding stations are: 



7°.38 5°.42 , 8°.80 , 

 the azimuths: 



iV217°ir7!-' , iV97°44'JE' , iV338°5y'.£; , 



the mutual angular distance, therefore, about 120°. 



The data are observations made during the winter months of January, 

 February, December 1912, January, P'ebruary, December 1913 and 

 January, February 1914, in total 240 observations. 

 Tiie standard deviations are : 



Ö, = 8.25 , Ö, = 7.79 , <7, = 7.96 , a, = 10.72 mm. 

 The correlation coefficients: 



j-j,=z 0.709 , r,,=: 0.868 , r,, = 0.579 



r„=: 0.532 , r.,, = 0.1475, »■,, = 0.402 



The criterion (j^''/f for the reliability of the c.c. calculated, 



mentioned above, cannot be applied in this case (as it was for ten day 



and monthly means) because daily observations are by no means 



to be considered as independent data. 



The condition-equations calculated from these values areas follows: 



.V, — 0.395 .c, + 0.568 .i-, + 0.234 x, it", = 957 j 



.ir, = 1.370 a-. — 0.525 .r,— 0.346.», 7^, =0.821 / ..(5) 



X. — 1,207 .r, — 0.321 .1;, — 205 *■ R„ = 0.905 ' 



x^ = 2.042 A-j — 0.873 x^ — 0.842 .r, R^ = 0.751 



The partial c.c, the mutual distances, the variation /(; of the partial 

 c.c. per degree of distance and the partial c.c. for equal distances 

 of 5° from the centre are : 



