322 CALIFORNIA ACADEMY OF SCIENCES. 



The mean difference is sufficiently near zero to retain 

 the old value, and we adopt for the present «o Mount He- 

 lena to Mount Diablo : 



324° or 31/^04 ±00/'64. 



This value will slightly change after the Mount Lola and 

 Bound Top observations shall have been finally adjusted. 

 The average local difference in azimuth is about 2/'l. 



At the stations Mount Diablo and Mount Helena the as- 

 tronomical azimuths were referred to a mark and not to a 

 triangulation point, and the same is the case at Mount Lola 

 and at Kound Top. 



The references to the stations marked by an asterisk ["^j 

 in the preceding table would therefore be arbitrary since 

 the results must depend on the adjustment of the directions 

 of the figure; but by applying a correction which is the 

 mean of all the corrections to the lines at the stations, the 

 reference of the astronomical meridian to the geometrical 

 figure of the triangulation is effected with respect to all di- 

 rections; thus for the two stations in question: 



At Mount Diablo: — 



Observed azimuth of the reference mark (Clayton) = 

 9° 42' 25. ''92 West of North; hence, astronomical azimuth 



of the mark = 170° 17' 84."08 



Or when reduced to the sea level-^ 170 17 34. 07 



At Mount Diablo the mean correction to the 



six adjusted directions is + 0/'023 



(±0."11); this added to the observed 



geodetic direction of the azimuth 



(25-49'17."194) gives = 25 49 17. 217 



Hence with the corrected direction to Mount 



Helena (see below)-- 359 59 59. 273 



The angle between the mark and Mount He- 

 lena, adjusted= 25 49 17. 94 

 and the astronomical azimuth referred to 



Mount Helena becomes 144 28 16. 13 



as given in the preceding table. 



