108 THE ADVANCE OF SCIENCE 



in the arts. Electric lighting is another 

 great gift of science to civilisation, the 

 practical effects of which have not yet 

 been fully developed, largely on account 

 of its cost. But those whose memories 

 go back to the tinder-box period, and 

 recollect the cost of the first lucifer 

 matches, will not despair of the results of 

 the application of science and ingenuity 

 to the cheap production of anything for 

 which there is a large demand. 



The influence of the progress of elec- 

 trical knowledge and invention upon that 

 of investigation in other fields of science 

 is highly remarkable. The combination 

 of electrical with mechanical contrivances 

 has produced instruments by which, not 

 only may extremely small intervals of 

 time be exactly measured, but the varying 

 rapidity of movements, which take place 

 in such intervals and appear to the or- 

 dinary sense instantaneous, is recorded. 

 The duration of the winking of an eye is 



