ON THE STUDY OF PHYSICS. 301 



the glass was really useful to her ? We learned with 

 pleasure the economic fact that she might dispense 

 with the lower half and see her whole figure notwith- 

 standing. It was also pleasant to prove by mathe- 

 matics, and verify by experiment, that the angular 

 velocity of a reflected beam is twice that of the mirror 

 which reflects it. From the hum of a bee we were 

 able to determine the number of times the insect flaps 

 its wings in a second. Following up our researches 

 upon- the pendulum, we learned how Colonel Sabine 

 had made it the means of determining the figure of 

 the earth ; and we were also startled by the inference 

 which the pendulum enabled us to draw, that if the 

 diurnal velocity of the earth were seventeen times its 

 present amount, the centrifugal force at the equator 

 would be precisely equal to the force of gravitation, so 

 that an inhabitant of those regions would then have 

 the same tendency to fall upwards as downwards. All 

 these things were sources of wonder and delight to us : 

 and when we remembered that we were gifted with the 

 powers which had reached such results, and that the 

 same great field was ours to work in, our hopes arose 

 that at some future day we might possibly push the 

 subject a little further, and add our own victories to 

 the conquests already won. 



I ought to apologise to you for dwelling so long 

 upon this subject ; but the days spent among these 

 young philosophers made a deep impression on me. I 

 learned among them something of myself and of human 

 nature, and obtained some notion of a teacher's vocation. 

 If there be one profession in England of paramount 

 importance, I believe it to be that of the schoolmaster ; 

 and if there be a position where selfishness and in- 

 competence do most serious mischief, by lowering the 

 moral tone and exciting irreverence and cunning where 



