506 THE POPULAR SCIENCE MONTHLY 



actually communicated their heat, the hot ones ought to have risen to 

 the top, and the cold ones subsided, so as to have made a material dif- 

 ference in the temperature." 15 Furthermore, these and many other 

 experiments afford us indications of his mental habit as a scientific 

 investigator. Conceptual processes find him at his best ; his theoretical 

 expectations and deductions are good. In experiment he is not so 

 happy, and what we understand by " fine " or refined work occurs sel- 

 dom. Thus, in the case just cited, Dalton infers " that the expansion 

 of water is the same both above and below the point of maximum den- 

 sity." But, when he comes to determine this crucial point precisely, 

 he goes wide of the mark, setting it at 36°. 



These references may enable us to grasp his manner of approach to 

 a problem, and to realize his general plan of attack upon the atomic 

 constitution of matter as it stood when he entered the field. 



I wish that space permitted me to present some consecutive account 

 of the doctrine of " matter " as it developed down the ages — but this is 

 impossible. The subject deserves attention, because so bemused in the 

 minds of the laity. And not only this. Scientific men themselves mis- 

 conceive it at times, not deliberately indeed, but because, absorbed in 

 researches of immediate moment, they have not troubled to follow the 

 marvelous story with patience. The long, tortuous endeavors that 

 culminated in Dal ton's atomic theory, with its kernel, the law of mul- 

 tiple ratios, are the tale of man's attempt to reduce his notion of " mat- 

 ter " to conceptual simplicity ; this to the end that it might be rendered 

 an obedient instrument. Freed from contingent accessories, the cen- 

 tral problem was this: Given such a vast multiplicity and variety of 

 phenomena as the " substantial " world presents, how can all be 

 grasped under a single, synthetic idea? Plainly, whenever man began 

 to reflect upon nature, he encountered this sphinx. The elusive, yet 

 persistent, relationship between the one and the many forms part of 

 ancient history in science no less than in metaphysics. 



Now, stating the situation very synoptically, and omitting the meta- 

 physical reference in favor of the natural-scientific, it may be affirmed 

 that the problem itself is also a many in a one. For, if we are to reach 

 clear concepts about natural phenomena, we must reckon with three 

 investigations at least. In the first place, a particular phenomenon 

 must be selected, and treated as the starting point. This done, it is 

 requisite to obtain an all-round view of what it is. In the second place, 

 one must proceed to elucidate its relations to other phenomena, prefer- 

 ably to those which evince evident, or apparent, kinship. In the third 

 place, order must be induced in the relations that have thus come under 

 observation by reducing them, as far as possible, to numerical expres- 

 sion. The primary methods of weighing, measuring and enumeration 



15 Ibid., p. 385. 



