250 THE SCIENTIFIC WORK OF GEORGE SIMON OHM. 
sketched in rough outline, are established even better by the truth of 
the law of the conduction of the current in metals here set forth, than 
they are by the experiments themselves from which they were derived. 
Effects of the galvanic current apparently the most varied are reduced 
to a striking simplicity.” 
What Ohm here and in the title calls “ theory ” is limited to the imme- 
diate consequences of his law determined inductively. It has nothing 
in method in common with the truly so-called “ theory” which he pro- 
posed much later in his famous work, ‘The Galvanic Battery,” and 
which he evolved deductively upon premises and partly hypothetical 
considerations. 
It is hence perfectly clear that Ohm discovered his law in the purely 
empirical way. Six years later, October, 1831, Pouillet appeared in 
an article on the application of the thermal battery to the determina- 
tion of the law of intensities in a constant current. What Pouillet 
believed himself the first to do, had already been done by Ohm in the 
above article in the most complete manner. Nowhere in his article is 
there so much as a suggestion of a hypothetical consideration which 
might have influenced him in the choice of his mathematical expression. 
The fact above stated that the formula first proposed was wrong, affords 
the most striking proof that those theoretical considerations which 
enabled him later to deduce his law mathematically, were at that time 
quite remote. 
Ohm’s name has been made immortal by this typical experimental 
treatise. It contains the discovery of the law of the intensity of the 
current, fully and completely, along with the most important conclu- 
sions to be deduced therefrom. In view of this inherent value it is 
undoubtedly to be preferred to the other most important works of Ohm, 
even to that one most famous of all his writings, ‘‘ The Galvanic Bat- 
tery Treated Mathematically,” which has always held the highest place 
in public estimation. In that experimental investigation he robbed 
nature of her secret and announced that everlasting and immutable 
law of nature which will outlive all the variations of theoretical beliefs. 
A mind like that of Ohm, trained and accustomed mathematically to 
inquire into the causes of phenomena, must soon have felt the need of 
showing that what he had inductively recognized was deductively a 
necessary consequent of simple conceptions as to the way in which 
electricity appears at the point of contact of different substances and 
disseminates itself in conducting materials. 
In the same year 1826 he published an article entitled: ‘‘ Attempt at 
a theory of the electroscopic phenomena produced by galvanic forces.” 
He reports the happy result of his endeavors in that he not only re-dis- 
covered, in this opposite way, the experimentally determined law of 
the intensities of current, but also found a second, no less important, 
the electroscopie law or law of tensions. 
