3073. A point equally important to the definition of these lines [of magnetic force] is, that they represent a determinate and unchanging amount of force. Though, therefore, their forms, as the exist between two or more centres or sources of magnetic power, may vary very greatly, and also the space through which they may be traced, yet the sum of power contained in any one section of a given portion of the lines is exactly equal to the sum of power in any other section of the same lines, however altered in form, or however convergent or divergent they may be at the second place. The experimental proof of this character of the lines will be given hereafter [ref].
Published before 1923