260 CONNECTION OF ELECTEICITY AND MAGNETISM. 



of his scientific career. But whereas the general course of scientific 

 method then consisted in the application of the ideas of mathematics 

 and astronomy to eacli new investigation in turn, Faraday seems to 

 have had no opportunity" of acquiring a technical knowledge of mathe- 

 matics, and his knowledge of astronomy was mainly derived from books. 



Hence, though he had a profound respect for the great discovery of 

 ]!»rewton, he regarded the attraction of gravitation as a sort of sacred 

 mystery, which, as he w^as not an astronomer, he had no right to gainsay 

 or to doubt, his duty being to believe it in the exact form in which it 

 w^as delivered to him. Such a dead faith was not likely to lead him to 

 explain new phenomena by means of direct attractions. 



Besides this, the treatises of Poisson and Ampere are of so technical 

 a form that to derive any assistance from them the student must have 

 been thoroughly trained in mathematics, and it is very doubtful if such 

 a training can be begun with" advantage in mature years. 



Thus Faraday, with his penetrating intellect, his devotion to science, 

 and his opportunities for experiments, was debarred from following the 

 course of thought which had led to the achievements of the French 

 X)hilosophers, and was obliged to explain the phenomena to himself by 

 means of a symbolism which he could understand, instead of adopting 

 what had hitherto been the only tongue of the learned. 



This new symbolism consisted of those lines of force extending them- 

 selves in every direction from electrified and magnetic bodies, which 

 Faraday in his mind's eye saw as distinctly as the solid bodies from 

 which they emanated. 



The idea of lines of force and their exhibition by means of iron filings 

 was nothing new. They had been observed repeatedly, and investigated 

 mathematically as an interesting curiosity of science. But let us hear 

 Faraday himself, as he introduces to his reader the method which in his 

 hands became so powerful :* 



"It would be a voluntary and unnecessary abandonment of most 

 valuable aid if an experimentalist who chooses to consider magnetic 

 j)ower as represented by lines of magnetic force were to deny himself 

 the use of iron filings. By their employment he may make many con- 

 ditions of the power, even in complicated cases, visible to the eye at 

 once; may trace the varying direction of the lines of force and determine 

 the relative polarity ; may observe in which direction the power is 

 increasing or diminishing; and in complex systems may determine the 

 neutral ipoints or places where there is neither polarity nor power, even 

 when they occur in the midst of powerful magnets. By their use prob- 

 able results may be seen at once, and many a valuable suggestion gained - 

 for future leading experiments." 



Experiment on lines of force. 

 In tills experiment each filing becomes a little magnet. The poles of 

 opposite names belonging to different filings attract each other and 



* Experimental Eesearches, 3284. 



