On a new method for determining the Earth's horizontal magnetic forces

Abstract

Since Gauss first introduced the present method of measuring magnetic forces, magneticians have been trying to obtain the increased accuracy required in modern physical measurements by refining details and introducing a number of corrections. The limit of such a procedure—which in this case has perhaps already been overstepped—is reached when the amount of added labor ceases to lead to a corresponding gain. It becomes necessary then to consider whether the method itself should not be abandoned.Electric currents can now be measured so accurately, and so much experience has been gained in winding standard coils, that it is worth enquiring whether magnetic forces cannot be conveniently measured by using artificially prepared magnetic fields as standards of comparison. To me it appears to be beyond doubt that greater accuracy can be obtained in this way with far less expenditure of labor, and, as far as fixed observatories are concerned, the time seems ripe to make the change.