318 



6. A second set of four slalions is: 



1. De Bilt, 2. Valencia, 3. Mülhansen i. E. and 4. Sjlt (W. coast 

 Schleswig Holstein). 



The distances from de Hilt lo tlie siin-oiindlMg stations are respect- 

 ively : 



9°.48, 4°.57. S-^.Sg 

 the azimuths : 



N 32° 40' E. N 11)1° 32' E, N 275° 13' E. 

 For these places the angular distance is likewise about 120°, and 

 they differ 60° with (he stations mentioned sub 5. 

 The standard deviations are 



Ö, = 8.25, «J, = 10.82, <J, = 7.30, <7, =: 8.9Ü mm. 

 Tiie correlation coefficients: 



»•,, = 0.63-5 , r,3=: 0.818 , ?•,,=: 0.864 

 »•,, = 0.480 , r,,=: 0.433 , »-,, = 0.528 

 from which the following condition-equations derive : 



.r; — 0.140 X, i- 0.494 .«, + 0.510 ,«, R, = 0.970 i 



.ï, = 2.41 7. Ï, — 0.852 .r, — 1. '134. B, i?, — 0.722 / ,q. 



.«3 = 1.457 A', — 0.146 .r, — 0.653,y, R, = 0.905 i 



.(,-, = 1 .595 .1-, — 0.188 X, — 0.693 x, R^ =z 0.934 ^ 



For the partial c.c, the distances not ^yet mentioned, the variation 

 /• for one degree distance and the c.c. for equal distances of 5°, 

 we find : 



Eithei' group proves that barometric oscillations in a central point 

 may be determined with great accuracy from only three well chosen 

 stations; the condition-equations for de Bilt {,i\) show even a greater 

 value of R than the corresponding equations (4) and the equations 

 for the three easterly stations: Dresden, Mfdhausen and Sylt all 

 show a value greater than 0.9. As one would perhaps be inclined 

 to overrate the value of such a c.c. for an actual calculation, it 

 seems not superfluous to remark that if — as in this case — the 

 standard deviation is relatively great, a large value of c.c. may 



