474 ELECTRICITY. 



ly as it will a feathery fibre as large as the needle. But 

 this attractive force will be sufficient to lift and to sus- 

 tain the feather, while it will not move the needle, on ac- 

 count of its great weight. If, however, we suspend the 

 needle in such a manner that it can be easily moved, the 

 attraction will be as manifest as in the case of any sub- 

 stance whatever. This may be done by means of a 

 thread. The needle suspended by it will swing like a 

 pendulum, and if the resin after being rubbed is brought 

 near it, the needle will be found to move sensibly to- 

 wards it. 



This single experiment with the amber stood for a long 

 time alone. It was not in these days, as it is now, the 

 custom to scrutinize with eager curiosity such phenome- 

 na, and to trace them back to their causes and con- 

 nexions. In modern times, however, this subject has 

 been very extensively examined. Many facts of a very 

 interesting character have been ascertained. Many 

 other phenomena have been observed and traced to the 

 same cause with the attraction of the amber. These 

 facts have been classified and arranged ; the manner in 

 which the cause of them operates in various circum- 

 stances, has been brought to view, and thus a most im- 

 portant and valuable science has arisen, which we call 

 in memory of the substance, whose properties first attract- 

 ed attention to the subject, the Science (<f Electricity. 



NATURE OF ELECTRICITY. 



The cause of the various phenomena hereafter to be 

 described, is called Electricity. It is generally consid- 

 ered a fluid, which pervades all bodies in nature. If it 

 is a fluid it must be extremely different in its nature from 

 all other fluids. There is much difficulty in regard to 

 the nature of three substances, whose effects are well 

 known, Light, Heat, and Electricity. If it were possi- 

 ble to describe the effects of these agents, the phe- 

 nomena caused by them, without adopting any theory in 

 regard to their intrinsic nature, we should prefer to do so. 

 But this is not possible. For convenience then of lan- 

 guage we call electricity a fluid, without meaning to ex- 



