John Dalton. 203 



the civilised world, to which it is a matter of indifference. 

 In this place, however, we must not forget Bew's paper on 

 blindness, see p. 100. 



It was in viewing the skies that Dalton saw his earliest 

 new truth. He thought of the air, why it was heavier and 

 lighter ; he held that it could not be so by being piled up 

 more or less highly above us, at certain times, but that the 

 change must take place in the lower portions of the atmo- 

 sphere. This change he found to be in the amount of 

 water in a state of vapour. We owe to him the explanation 

 of barometric differences indicating the character of the 

 weather, and the beginning of a new impulse to the study 

 of climate, in reality the true beginning of meteorology. 



On this subject we prefer to give the opinion of a dis- 

 tinguished meteorologist, Alexander Buchan. He says in 

 his handy book of that science, 1868, p. 5 : 



' The publication of Dalton's " Meteorological Essays " 

 in 1793 marks an epoch in meteorology. It was the first 

 instance of the principles of philosophy being brought to 

 bear on the explanation of the complex and varied phe- 

 nomenon of the atmosphere. The idea that vapour is an 

 independent elastic fluid, and that all elastic fluids, whether 

 alone or mixed, exist independently; the great motive 

 forces of the atmosphere. The theory of winds, with their 

 effect on the barometer, and their relation to temperature 

 and rain ; observations on the height of clouds, on thunder, 

 and on meteors ; and the relation of magnetism and the 

 aurora borealis, are some of the important questions dis- 

 cussed in these remarkable essays, with an acuteness, a 

 fulness, and a breadth of view, which leave nothing to be 

 desired/ 



In fact Dalton brought to Manchester a new science in 



