HISTORY OF THE ATOMIC THEORY. 57 



gave his first lecture on Tuesday preceding my conclusion. 

 I was an auditor in this case, the first time, and had an 

 opportunity of surveying the audience. Amongst others of 

 distinction the Bishop of Durham was present. 



" In lecturing on optics I got six ribbands, blue, pink, lilac, 

 and red, green, and brown, which matched very well and told 

 the curious audience so. I do not know whether they 

 generally believed me to be serious, but one gentleman came 

 up immediately after and told me he perfectly agreed with 

 me : he had not remarked the difference by candle light." 



This letter concludes characteristically by " The rain has 

 been 27^ inches last year." 



Like many students whose nerves are not easily affected, 

 Dalton liked tobacco. A thorough explanation of its action 

 on various constitutions seems to have hitherto escaped the 

 research of medical men, most of them being content either 

 to admire it, or to detest it, according as it may suit them- 

 selves. The following letter to Mr. John Rothwell gives 

 Dalton's taste. 



London, Jan. 10th, 1804. 



" I was introduced to Mr. Davy, who has rooms adjoining 

 mine in the Royal Institution : he is a very agreeable and 

 intelligent young man, and we have interesting conversations 

 in an evening : the principal failing in his character is, that 

 he does not smoke. Mr. Davy advised me to labour my first 

 lecture : he told me the people here would be inclined to form 

 their opinion from it; accordingly I resolved to write my first 

 lecture wholly ; to do nothing but to tell them what I would 

 do, and enlarge on the importance and utility of science. I 

 studied and wrote for nearly two days, then cjjilculated to a 

 minute how long it would take me reading, endeavouring to 

 make my discourse about fifty minutes. The evening before 

 the lecture, Davy and I went into the theatre : he made me 

 read the whole of it, and he went into the furthest comer; 

 then he read it, and I was the audience; we criticised upon 

 I 



