vii LAW AND PRINCIPLE 183 



benefits not only on our own country but also on the world at 

 large, when compared with the grandiose monuments to political, 

 naval and military nonentities is, it must be confessed, a some- 

 what humiliating reflection on the lack of appreciation of science 

 shown in the English Temple of Fame. But, after all, this is 

 of little moment, for the names of Darwin and Joule will live 

 for ever in the minds and hearts of all those who appreciate 

 scientific worth." 



The discovery of a law of Nature is always of great 

 advantage to scientific progress. By the warp and woof 

 of experiment, the man of science weaves a pattern 

 from the threads of evidence, and presents the result to 

 the world for anyone to use or improve. A further 

 example of this is afforded by the discovery, in 1826, by 

 George Simon Ohm, the son of a German locksmith, of 

 the law of electricity named after him. 



Before Ohm commenced his investigations, many men 

 of science had studied the wonderful and manifold 

 effects of the electric current. Remarkable phenomena 

 were observed, but they formed only a tangled skein 

 until Ohm discovered a simple law stating the rela- 

 tionship between cause and effect in electricity. The 

 law is simply that the rate of flow of an electric current 

 is equal to the electric pressure divided by the resistance 

 offered to the current by the wire or other conductor 

 through which it is flowing. Ohm was working indepen- 

 dently and alone when he discovered this law ; and even 

 after he had established it beyond question he received 

 little recognition for his work, while from many sides 

 it was sharply criticised. It often happens that a 

 prophet is not without honour except in his own country 

 and among his own people, and this was the case with 

 Ohm, the importance of the work of the unassuming 

 German teacher being recognised in England before it 

 was in his native land. 



