868 
MESSRS. J. MILNE AND T. GRAY ON SEISMIC EXPERIMENTS. 
IX., X., XI., and XII.— Falls of ball on the line A B. Ball fell 35 feet upon a large 
block of iron which had been placed in the hole made by the ball. 
In these experiments a number of similar saucers containing equal quantities of 
mercury were substituted for the bottles. 
Number of the experiment. 
Station. ' 
IX. 
X. 
XI. 
XII. 
Time of 
motion. 
Observer, 
Time of 
motion. 
Observer. 
Time of 
motion. 
Observer, 
Time of 
motion. 
Observer. 
feet. 
100 
300 
450 
seconds. 
9 
10 
Milne . . 
Gray . . 
seconds. 
14 
8 or 9 
5 
Milne . . 
Angas . . 
Nembrini . 
seconds. 
15 
7 
8 
Gray . . 
Angas . . 
Nembrini . 
seconds. 
20 
*8 
Milne 
Nembrini 
During the XI. Experiment a saucer of mercury was observed at the 75 feet station 
on the line J K by Brindley, but no motion was detected. 
XIII., XIV., XV., and XYI. -Falls of ball on the line J K to show the effect of the 
pond in cutting off* the transmission of vibrations. Ball fell 85 feet, upon the 
block of iron, which had been almost driven out of sight. 
Number of the experiment. 
Station. 
XIII. 
XIV. 
XY. 
XVI. 
Time of 
motion. 
Observer. 
Time of 
motion. 
Observer. 
Time of 
moticn. 
Observer. 
Time of 
motion. 
Observer. 
feet. 
0 
30 
60 
90 
120 
seconds. 
9 
8 
Milne . . 
Tamaki . 
seconds. 
10 
10 
5 
Nembrini . 
Tamaki 
Milne . . 
seconds. 
9 
1 
0 
Nembrini . 
Tamaki 
Milne . . 
seconds. 
"9 
0 
0 
Nembrini 
Tamaki 
Milne 
XVII.— Fall of ball on the line A H (see section). Ball fell 35 feet. 
Station 140 feet. When the ball fell the observer felt a strong shake and the mercury 
in the saucer was in consequence put in motion for 12 seconds. 
Station 100 feet. Here also a strong shake was felt, but as the ground was in a 
continuous state of vibration due to the working of a neighbouring engine it was 
difficult to say how much of the motion produced in the mercury was alone due 
to the blow. 
