June 23, 1911] 



SCIENCE 



951 



to about 60 ft. in length, the direction being as 

 with the other coils. This side call B. 



Charged a battery of ten plates, four inches 

 square, made the coil on B side one coil, and con- 

 nected its extremities by a copper wire passing to 

 a distance and just over a magnetic needle (three 

 feet from iron ring). Then connected the ends 

 on one of the pieces on A side with the battery: 

 immediately a sensible effect on needle. It oscil- 

 lated, and settled at last in original position. On 

 breaking connection of A side with the battery, 

 again a disturbance of the needle. 



Later he varied the experiment and 

 writes : 



In place of the indicating helix, our galvano- 

 meter was used, and then a sudden jerk was per- 

 ceived when battery communication was made and 

 broken, but it was so slight as to be scarcely 

 visible. It was one way when made and the otlier 

 way when broken, and the needle took up its nat- 

 ural position at intermediate times. 



The device which Faraday described 

 was a transformer. The impulses which 

 he saw in the needle were due to induced 

 currents. He was at once led by this to 

 the invention of the first dynamo, which he 

 constructed during the same month. 



If any person had asked Faraday that 

 exasperating question, what is all this 

 worth in pounds, shillings and pence, or 

 what are your services really worth per 

 student hour, he would have been utterly 

 unable to make a satisfactory reply. The 

 effects were so minute that it was with 

 difficulty that they could be seen. The 

 forces involved were utterly insignificant. 

 His dynamo was worthless as a machine. 

 Who could then have imagined that these 

 feeble impulses would some day be pumped 

 through wires to light large cities, and to 

 move heavy cars loaded down with pas- 

 sengers? Who could have then believed 

 that articulate speech would ever be trans- 

 mitted by them? Who could then have 

 believed that ships on the ocean would 

 some day be in constant communication 

 with the land, by means of such impulses 



transmitted through space, and that a ship 

 in distress would thus be able to call for 

 help? Had any prophet foretold all of 

 this at that time, it would have been called 

 the idle fancy of a foolish brain. And yet 

 all of these great things followed directly 

 from those simple experiments. 



And the end is not yet. We are begin- 

 ning to see the importance of saving our 

 fuel. We may be able to grow trees, but 

 we can not grow coal. An age of water 

 power is before us when vast amounts of 

 power will be thus obtained, and trans- 

 mitted, by these methods devised by Fara- 

 day, to distant cities. Millions upon mil- 

 lions of dollars are now invested, and vast 

 armies of men are employed in enterprises 

 which followed directly from these simple 

 experiments. 



When Helmholtz visited London in 1853 

 he wrote to his wife an account of his visit 

 to Faraday, in which he says: 



Those were splendid moments. He is as simple, 

 charming and unaffected as a child; I have never 

 seen a man with such winning ways. He was, 

 moreover, extremely kind, and showed me all 

 there was to see. That indeed was little enough — 

 . for a few wires and some old bits of wood and 

 iron seem to serve him for the greatest discoveries. 



It is often said that work of such char- 

 acter is not for all ; that only a few of the 

 elect are capable of doing it. In a sense 

 this is true. There are comparatively few 

 who will in their younger days submit to 

 the agonizing struggle through which one 

 must go, in order that he may gain control 

 of his mental faculties. If he is mentally 

 slow in his sense perception, it will be 

 necessary for him to engage, persistently, 

 for hours, days and years, in a mental 

 struggle with problems which tax his ut- 

 most powers. It is in this way that one 

 finally acquires the capacity for careful 

 and logical and persistent thinking. It 

 goes without saying that there are com- 

 paratively few who will submit to such an 



