HI8T0KY OF THE ATOMIC THEORY. 277 



old residence and from that time lived alone. In 1832, at the 

 age of 66, he ascended Helvellyn as firmly as ever, took the 

 ladies an excursion in Cumberland to see his old friends, play- 

 fully introducing the two elder Miss Johns as his daughters, 

 and their cousins, the younger ladies, as his granddaughters. 

 But we cannot follow him on the hills; of them he never 

 seems to have wearied, nor did he ever weary of his old friends 

 there, nor of the study which first made him look on the 

 peculiar aspects of nature at that spot. The place seemed 

 to be a memory both for his intellect and his heart, and his 

 love for the district shows how permanent in him were the 

 feelings of both. 



It was not until 1837 that Dal ton felt in any decided manner 

 the progress of age, although long before that time his energy 

 and originality had diminished. Properly speaking he had, 

 like many other gifted persons, only one period of great 

 originality, occurring immediately at the conclusion of his 

 education, so to speak. At that period it frequently happens 

 that the mind makes choice of the materials with which it 

 will work, and has some more or less distinct idea of the 

 conclusion, whilst the rest of the life is directed to its elucida- 

 tion or expansion. 



On April 18th, 1837, he was disabled for a while by 

 paralysis, and although he wrote some memoirs after this period 

 he never entirely recovered. He fell suddenly to the floor after 

 his usual morning's labor of recording the state of the baro- 

 meter and thermometer. His friend Peter Clare was his con- 

 stant companion, and to the end of his life acted both as secretary 

 and friend, with an amount of 'reverence and affection that is 

 seldom found. He noted down the observations when Dalton 

 was ill, and took down at his request all the minute par- 

 ticulars connected with his illness and his medicines ; for every 

 illness and every dose was like a chemical experiment with 

 Dalton. 



