145 
ARTICLE VI. 
On a Method of Facilhtating the Observations of Deflection. By 
Caru Friepricu Gauss. 
[From the Resultate aus den Beobachtungen des Magnetischen Vereins. 1839.] 
1. Tr, in addition to the magnetic force of the earth, another 
force be brought to act on a magnetometer statically, but in a 
direction inclined to the magnetic meridian, the needle will take 
up a new position of equilibrium, and the magnitude of the de- 
flection may serve as a measure of the superadded force. The 
determination of the amount of deflection requires not only that 
the new position of equilibrium should lie within the limits of 
the scale, but, inasmuch as it is not desirable to wait until the 
bar is at perfect rest, the extent of its remaining vibration ought 
not to exceed these limits. Supposing the bar to have been 
stationary whilst under the influence of the earth’s magnetic 
force alone, and the additional force to be brought at once into 
full action,—an oscillation will commence, having for its middle 
point the new position of equilibrium, and for its two extremities, 
the previous position on the one side, and a point equidistant 
from the middle of the vibration on the other. If the new posi- 
tion of equilibrium should be but little within the scale, it is 
clear that, without having recourse to some artifice, the slow 
decrease of the arc of vibration would make it necessary to 
wait a considerable time before that position could be deter- 
mined. On account of the hourly change of the declination, 
this delay would in all cases detract from the trustworthiness 
and usefulness of the determination, and would vitiate it almost 
entirely in cases where the superadded force is liable to consi- 
derable alteration in short periods,—as in the case of galvanic 
currents. 
2. This inconvenience may be remedied by the following 
simple method. Let the additional force be at first brought 
into action only during the third part of the time of one vibra- 
tion; let it then be suspended for an equal time, and after a 
similar interval brought into continued action. For example, 
supposing the time of vibration of the magnet to be 30 seconds, 
and that it is desired to measure the deflection produced by a 
VOL. Ill. PART Ix. L 
