OF THE OBSERVATORY OF CAMBRIDGE BY GALVANIC SIGNALS. 



501 



By D's and T's signal-times, May 17. 



No. of 

 comparisons. 



G,= 0,185. 

 G 3 = 0,344. 



26 

 27 



G,+ G 3 



2 



= 0,264 53 



C 2 = 0,290 41 



C 4 = 0,264 45 



Ct + Ci 



= 0,277 . 



86 



G l + G 3 



- C, - - 0,026, 



and G 3 — 



C 4 



= + 0,067. 



By T's and D's signal-times, May 18. 



No. of 

 comparisons. 



G t = 0,548 31 



G 3 = 0,726 27 



G, + G 3 •■■■•• 



— = 0,637 58 



d = 0,557 37 



C 4 = 0,568 40 



c + c t 



0,563 77 



C 4- C '■ 



.-. — 3 - C 2 = + 0,080, 

 2 



and G 3 - 9l±S!* = + o,i63. 



By D's and B's signal-times, May 17- 



No. of 

 comparisons. 

 f. 

 G, = 0,281 27 



G 3 = 0,362 27 



G l + G 3 



2 



= 0,322 54 



C 2 = 0,320 40 



C t = 0,269 45 



c 2 + c 4 — 



— ^=0,295 85 



G. + G 3 _ '• 



— S -r C 2 = + 0,002, 



and G 3 = + 0,067. 



By T's and B's signal-times, May 18. 



No. of 

 comparisons. 

 1. 



G 4 = 0,726 31 



G 3 = 0,678 27 



G, + G 3 



= 0,702. 



58 



C 8 = 0,589 37 



C 4 = 0,578 40 



c 2 + a 



2 



= 0,584 77 



G l + G 3 



2 



- C 2 = +0,113, 



and G 3 - + 0,094. 



If we consider all the eight results to be of equal weight, the mean excess of the Cam- 

 bridge signal-times above the Greenwich signal-times (the time-pieces having virtually the 

 same rates), is greater for the signals given at Greenwich than for those given at Cambridge 

 by the mean quantity S ,070. The interval occupied by the transmission of the galvanic 

 action is therefore apparently S ,0S5. This quantity can only be regarded as a limit which 

 the interval of transmission did not exceed. The whole of it may with much probability be 

 accounted for by supposing the start of the needle to catch the eye of the observer sooner at 

 the signal-giving place than at the signal-receiving place, the galvanic action being of greater 

 intensity at the former. During the whole of the experiment the air was dry and the 

 insulation good. The number of battery-cells used at each station was 72. 



