HISTORY OF THE ATOMIC THEORY. 31 



in suitable studies. On March 1st, 1799, he read to the 

 Literary and Philosophical Society* " Experiments and 

 observations to determine whether the quantity of rain and 

 dew is equal to the quantity of water carried off by the 

 rivers and raised by evaporation; with an inquiry into the 

 origin of springs." In this he treats, — 

 "1. Of the quantity of rain and dew. 



2. Of the quantity of water that flows into the sea. 



3. Of the quantity of water raised by evaporation. 



4. Of the origin of springs." 



The first three are accompanied by experiments, but there 

 is a looseness in the calculations which renders the paper rather 

 like a sketch of the subject. He, however, collects a great 

 deal of information as to the annual fall of rain in various 

 places, and in a note explains clearly, as before alluded to, his 

 ideas as to the state of aqueous vapour in the air. The loose- 

 ness of expression is not at all times with him an indication of 

 want of decision, but his peculiar style of writing, as if every 

 one knew the subject, and were ready to draw out his reasoning 

 into all its details, as soon as expressed. His experiments, 

 begun with the hand, seem often finished with the head, so 

 rapidly are his conclusions come to, and the natural law estab- 

 lished in his mind. Even now we can add little to the relation 

 between evaporation, rain, and dew, and on the origin of 

 springs he is clear, quick, and decisive, saying that they come 

 from the rain. This subject had been much disputed ; filtra- 

 tion from the sea having been a favourite method of obtaining 

 the water, as well^s subterranean reservoirs like those of Father 

 Kircher, who shows them in engravings continually boiling 

 out from the centre of the earth. Dalton was not the first to 

 suggest the explanation, of course, but the subject was 

 sufficiently uncertain to call for elucidation. On April 12th, 



* Memoirs of the Literary and Philosophical Society of Manchester. Vol. 

 v., p. 346. 



