THE SCIENTIFIC WORK OF GEORGE SIMON OHM. 249 
failure in the too limited range of his experiments and in the fluctua- 
tions in the force of the galvanic battery. Much later the invention 
of the constant cell obviated these fluctuations. 
In the summer of the same year, 1825, and in the same volume of 
Schweigger’s Journal, appears a letter from Ohm to the editor. He says 
in consequence of more extended experiments he is moved to replace 
his formula with a new but analogous one. In this the force would only 
vanish for v = ~. 
Not long after this, in the spring of 1826, vol. xLIv of Schweigger’s 
Journal contained that wonderful pioneer work which contains the 
experimental discovery of the law of the intensity of the current. Its 
title is: ‘‘ Determination of the law according to which metals conduct 
contact electricity, together with the outlines of a theory of Volta’s 
apparatus and the Schweigger’s galvanoscope.” In the introduction 
to this article Ohm expresses the hope that he is in a position to 
propose what will appear to be a true law of nature. First, on account 
of its perfect agreement with experiments extended in all directions; 
second, and especially because of its simplicity which extends it to all 
our experience with the electric current. A simplicity such as is only 
found in truth. 
The “fluctuations of force ” had disturbed Ohm greatly in his former 
experiments, Poggendorff suggested that he should use a thermo-electric 
instead of a hydro-electric battery. This he did and now the law ap- 
peared in perfect distinctness trom his measurements. The inten- 
sity of the current is directly proportional to the exciting force and 
inversely proportional to the total resistance. This he represented in the 
equation 
X= 
‘‘wherein X is the intensity of the magnetic effect of the conductor 
whose length is 7, a and b represent constant quantities depending 
upon the exciting force, and the resistance to conductivity of the other 
parts of the circuit. 
In this law he held in his hand the key to the various riddles before 
which physicists had hitherto stood helpless. And indeed he knew 
how to use that key! Farther on he says: ‘‘Our equation has now 
sufficiently established itself as the accepted representative of nature 
by the correctness with which it always repeats the results obtained in 
such profusion from the thermo-electric battery. Let us follow it far- 
ther and see what it may still hold concealed in its lap.” 
Ohm then developed the peculiarities of the galvanie battery and 
galvaniscope, which till then had appeared so confused and unintelli- 
ble. And we in our text-books to-day follow his development. Bub- 
bling over with joy in the feeling that he had beheld the face of truth. 
he may well feel a justifiable pride. At the close of that wonderful 
work he exclaims: “The theories of the battery and galvaniscope, here 
