ill. 



ON December 7, 1854, he gave his introductory 

 address, in Lille, to students of technical science. 

 He spoke in praise of science, and of theory- 

 " Without theory, practical work becomes mere 

 routine, by force of habit. Theory, and theory 

 alone, can stir and develop the inventive spirit. 

 Your business, your especial business, must be, to 

 have nothing in common with those narrow minds 

 which despise everything in science that has no 

 immediate application." He took the story of 

 Franklin, who was asked what was the use of some 

 new fact of science, and answered, What is the 

 use of a baby ? And he illustrated it by (Ersted's 

 discovery of the electric magnet, which led to 

 telegraphy : " So it is with every theoretical dis- 

 covery : its only merit is, that it exists : it bids you 

 to hope : and that is all." 



In 1855, he writes to Chappuis : 



"At my fullest lectures, I have 250 or 300 

 men : and 21 students have put down their names 



