238 THE PRINCIPLES OF SCIENCE. 



in nature, in which the mutual relations of electricity and 

 gravity would come into play ; he pictures to himself the 

 planets and the comets charging themselves as they ap- 

 proach the sun ; cascades, rain, rising vapour, circulating 

 currents of the atmosphere, the fumes of a volcano, the 

 smoke in a chimney become so many electrical machines. 

 A multitude of events and changes in the atmosphere 

 seem to be at once elucidated by such actions ; for a 

 moment his reveries have the vividness of fact. ' I think 

 we have been dull and blind not to have suspected some 

 such results,' and he sums up rapidly the consequences of 

 his great but imaginary theory ; an entirely new mode of 

 exciting heat or electricity, an entirely new relation of the 

 natural forces, an analysis of gravitation, and a justifica- 

 tion of the conservation of force. Such were Faraday's 

 fondest dreams of what might be, and to many another 

 philosopher they would have been a sufficient basis for 

 the writing of a great book. But Faraday's imagination 

 was within his full control ; as he himself says, ' Let the 

 imagination go, guarding it by judgment and principle, 

 and holding it in and directing it by experiment.' His 

 dreams soon took a very practical form, and for many 

 subsequent days he laboured with ceaseless energy, on the 

 staircase of the Koyal Institution, in the clock tower of 

 the Houses of Parliament, or in the Shot Tower at 

 Southwark, raising and lowering heavy weights, and com- 

 bining electrical helices and wires in every conceivable 

 way. His skill and long experience in experiment were 

 severely taxed to eliminate the effects of the earth's mag- 

 netism, and time after time he saved himself from accept- 

 ing mistaken indications, which to another man might 

 have seemed conclusive verifications of his theory. When 

 all was done there remained absolutely no results. ' The 

 experiments/ he says, ' were well made, but the results are 

 negative;' and yet he adds, 'I cannot accept them as 



