MY SCHOOLS AND SCHOOLMASTERS. 335 



health — which was something different from the malady of self-right- 

 eousness. I concentrated my chief attention upon mathematics, phys- 

 ics, and chemistry. To the illustrious chemist Bunsen I am specially 

 indebted. He was a man of fine presence, tall, handsome, courteous, 

 and without a trace of affectation or pedantry. He merged himself 

 in his subject ; his exposition was lucid, and his language pure ; he 

 spoke with the clear Hanoverian accent which is so pleasant to Eng- 

 lish ears. He was every inch a gentleman. After some experience of 

 my own, I still look back on Bunsen as the nearest approach to my 

 ideal of a university teacher. Professor Stegmann gave me the sub- 

 ject of my dissertation when I took my degree. Its title in English 

 was, " On a Screw Surface with Inclined Generatrix, and on the Con- 

 ditions of Equilibrium on such Surfaces." I resolved that if I could 

 not, without the slightest aid, accomplish the work from beginning to 

 end, it should not be accomplished at all. Wandering among the pine- 

 woods, and pondei'ing the subject, I became more and more master of 

 it ; and when my dissertation was handed in to the Philosophical 

 Faculty it did not contain a thought that was not my own. Con- 

 tinuing to work strenuously but happily till the autumn of 1850, I 

 then came to England. But I soon returned to Germany. To those 

 Marburg days I look back with warm affection, both in regard to na- 

 ture and to man. To Berlin I went in the beginning of 1851. Mag- 

 nus, Dove, Mitscherlich, Heinrich and Gustav Rose, Ehrenberg, Riess, 

 Du Bois-Reymond, and Clausius were the scientific stars of the uni- 

 versity at that time. From all these eminent men I received every 

 mark of kindness, and formed with some of them enduring friend- 

 ships. Helmholtz was at this time in Kunigsberg. He had written 

 his renowned essay on the " Conservation of Energy." In his own 

 house I had the honor of an interview with Humboldt. He rallied me 

 on having contracted the habit of smoking in Germany, his knowledge 

 on this head being derived from my little paper on a water-jet, where 

 the noise produced by the rupture of a film between the wet lips of a 

 smoker is referred to. He gave me various messages to Faraday, de- 

 claring his belief that he (Faraday) had referred the annual and diui'- 

 nal variation of the declination of the magnetic needle to their true 

 cause — the variation of the magnetic condition of the oxygen of the 

 atmosphere. I was interested to learn from Humboldt himself that, 

 though so large a portion of his life had been spent in France, he 

 never published a French essay without having it first revised by a 

 Frenchman. In those days I not unfrequently found it necessary to 

 subject myself to a process which I called depolarization. My brain, 

 intent on its subjects, used to acquire a set, resembling the rigid polar- 

 ity of a steel magnet. It lost the pliancy needful for free conversa- 

 tion, and to recover this I used to walk occasionally to Charlottenburg 

 or elsewhere. From my experiences at that time I derived the notion 

 that hard thinking and fleet talking do not run together. 



