51 6 
Mr. Babbage on electrical 
Experiment 17. 
The apparatus being in precisely the same state as in the 
last experiment, the lamp was not lighted, and the following 
observations were registered. 
Oscillation of 
wax needle. 
Diff. 
2 Diff- 
Mean position. 
O 
O 
O 
L . . . 259 
R ... 255 
4 
2 
257 
L . . . 258.5 
R . . . 256 
2.5 
I.25 
257.25 
The apparatus was set in motion 
the lamp 
revolving, but not being lighted. 
L . . . 258.8 
R . . . 256 
2.8 
M 
257.4 
L . . . 258.8 
R . . . 256.4 
L . . . 258.6 
2.4 
1.2 
1.05 
257.6 
R . . . 256.5 
2.1 
257-55 
L . . . 258.8 
R . . . 257.2 
1.6 
0.8 
258 
L . . . 258.2 
R . . . 256.8 
i -4 
0.7 
257-5 
L . , . 258.2 
This experiment clearly proves, both from the stationary 
position of the mean point, and from the decrease of the arc 
through which the needle oscillated, that no vibrations are 
communicated from the jack to the needle. 
I now tried the effect of winding up the jack, and found 
that it did not increase the arc half a degree on each side, 
although it caused the needle and silver wire to oscillate 
slightly, as a pendulum. 
Considering it possible, by means of an agate cap, to 
suspend the various needles employed in these experiments, 
