xxvi.] CHAEACTEE OF THE EXPERIMENTALIST. 589 



ceeded." He describes the phenomenon in somewhat figu- 

 rative language as the magnetisation of a ray of light, 

 and also as the illumination of a magnetic curve or line 

 of force. He has no sooner got the effect in one case, 

 than he proceeds, with his characteristic comprehensive- 

 ness of research, to test the existence of a like phenomenon 

 in all the substances available. He finds that not only 

 heavy glass, but solids and liquids, acids and alkalis, 

 oils, water, alcohol, ether, all possess this power ; but he 

 was not able to detect its existence in any gaseous sub- 

 stance. His thoughts cannot be restrained from running 

 into curious speculations as to the possible results of the 

 power in certain cases. " What effect," he says, " does this 

 force have in the earth where the magnetic curves of the 

 earth traverse its substance ? Also what effect in a mag- 

 net ? " And then he falls upon the strange notion that 

 perhaps this force tends to make iron and oxide of iron 

 transparent, a phenomenon never observed. We can meet 

 with nothing more instructive as to the course of mind by 

 which great discoveries are made, than these records of 

 Faraday's patient labours, and his varied success and 

 failure. Nor are his unsuccessful experiments upon the 

 relation of gravity and electricity less interesting, or less 

 worthy of study. 



Throughout a large part of his life, Faraday was pos- 

 sessed by the idea that ^gravity cannot be unconnected 

 with the other forces of nature. On March igth, 1849, 

 he wrote in his laboratory book, " Gravity. Surely this 

 force must be capable of an experimental relation to elec- 

 tricity, magnetism, and the other forces, so as to bind it 

 up with them in reciprocal action and equivalent effect ? " x 

 He filled twenty paragraphs or more with reflections and 

 suggestions, as to the mode of treating the subject by ex- 

 periment. He anticipated that the mutual approach of 

 two bodies would develop electricity in them, or that a 

 body falling through a conducting helix would excite a 

 current changing in direction as the motion was reversed. 

 " All this is a dream," he remarks ; " still examine it by a 

 few experiments. Nothing is too wonderful to be true, if 



1 See also his more formal statement in the Experimental Researches 

 in Electricity, 24th Series, 2702, voL iii. p. 161. 



