THE HISTORY OF OHM'S LAW- 6ii 



expei'iniont. This is a serious mistake on the part of Ohm and it is 

 hard to see just why ho did himself this injustice. He may have 

 assumed that the scientific public was familiar with all of his printed 

 papers — an unsafe assumption at any time — and that direct reference 

 to them was unnecessary. Ohm's book was only made possible by his 

 experimental work and everything of value in it is the direct outcome of 

 the laboratory, yet in the book Ohm writes as if the results reached were 

 deductive and based on the three hyjiotheses cited above. In this Ohm 

 laid the ground for the misunderstanding of his work by his contem- 

 poraries, who did not realize that its basis was experimental and there- 

 fore subject only to experimental proof or disproof. 



Perhaps Ohm thought that the rather meager foundation of experi- 

 mental data would be regarded as inadequate for the superstructure, or 

 it may be that he really felt that the experiments had led him to the 

 knowledge of the fundamental causes of the phenomena of conduction, 

 and that his theory was more secure by being logically developed from 

 these supposed fundamental truths. In either event he retarded rather 

 than helped his cause. A third reason that might be assigned would be 

 his desire, supposing him to have it, to be regarded as a deductive 

 rather than as an inductive philosopher. He had, of course, imbibed 

 some of the modern view of the importance of experimentation, else he 

 would not have experimented, but he very likely still retained a good 

 deal of the old Greek notion that by a process of pure reasoning one may 

 reach new truth. In this case experimentation is not so much a source 

 of new knowledge as a new form of thought stimulation. From such a 

 viewpoint the experiments of Ohm had indeed served their purpose so 

 soon as they were completed and he was quite right in ignoring them. 

 Such a view of Ohm's position is strengthened by the fact that he 

 seems to have taken no pains to remove the impression, universal in his 

 day and which persists somewhat even to the present, that his laws were 

 based on theory only and had no experimental origin or support. 



So far then as Ohm is concerned we must conclude that however 

 much he may have valued his experimental work for himself, he was 

 well content that the public should consider his laws as being of 

 theoretic and not of experimental origin. 



The view which the scientific public early reached as to the value of 

 Ohm's work is well expressed in the following paragraph taken from 

 Cajori's "History of Physics" (pp. 230-1): 



The following year Ohm published a book entitled "Die Galvanisehe Kette, 

 mathematisch bearbeitet. " It contained a theoretic deduction of Ohm's la^, 

 and became far more widely known than his article of 1826, giving his experi- 

 mental deduction. In fact, his experimental paper was so little known that the 

 impression long prevailed and still exists that he based his law on theory and 

 never established it empirically. This misapprehension accounts, perhaps, for the 



