10 AUTOBIOGRAPHY OF FRANCIS ARAGO. 



professor. Whence did you get it ? " " From one of 

 your papers." " Why did you choose it ? was it to bribe 

 me ? " " No ; nothing was farther from my thoughts. 

 I only adopted it because it appeared to me preferable." 

 " If you are unable to explain to me the reasons for your 

 preference, I declare to you that you shall receive a bad 

 mark, at least as to character." 



I then entered upon the details which established, as I 

 thought, that the method of double integrals was in all 

 points more clear and more rational than that which 

 Lacroix had expounded to us in the amphitheatre. 

 From this moment Legendre appeared to me to be sat- 

 isfied, and to relent. 



Afterwards, he asked me to determine the centre of 

 gravity of a spherical sector. " The question is easy," 

 I said to him. " Very well ; since you find it easy, I 

 will complicate it : instead of supposing the density con- 

 stant, I will suppose that it varies from the centre to the 

 surface according to a determined function." I got 

 through this calculation very happily ; and from this 

 moment I had entirely gained the favour of the ex- 

 aminer. Indeed, on my retiring, he addressed to me 

 these words, which, coming from him, appeared to my 

 comrades as a very favourable augury for my chance of 

 promotion : " I see that you have employed your time 

 well ; go on in the same way the second year, and we 

 shall part very good friends." 



In the mode of examination adopted at the Polytechnic 

 School in 1804, which is always cited as being better 

 than the present organization, room was allowed for the 

 exercise of some unjustifiable caprices. Would it be 

 believed, for example, that the old M. Barruel examined 

 two pupils at a time in physics, and gave them, it is said, 



