Any method of obtaining measurements or comparisons, in which the
measurement is correct when the deflection of the galvanometer or other
indicator is zero, nought or null. The Wheatstone Bridge (see Bridge,
Wheatstone) is an example of a null method.

Two obvious advantages attach to null methods in electric galvanometer
work. One is that an uncalibrated galvanometer can be employed. The
other is that a galvanometer of any high degree of sensitiveness can be
employed, there being no restriction as to its fineness of winding or
highness of resistance.

“Upper case Omega Graphic“.
(Greek capital” Omega”) symbol for megohm.
[Transcriber's note: Now used for ohms.]

“Lower case Omega Graphic“.
(Greek omega) symbol for ohm.
[Transcriber's note: Now used for angular velocity, 2*PI*frequency.]