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SCIENCE. 



[N. S. Vol. XVIII. No. 400. 



startling solution of our problem. He re- 

 places the conventional ether by a granular 

 medium, generally homogeneovis, closely 

 packed, and having a density ten thousand 

 times that of water. Here and there the 

 medium is strained, producing what Rey- 

 nolds calls 'singular surfaces of misfit' 

 between the normally piled grains and 

 their partially displaced neighbors. These 

 surfaces are wave-like in character, and 

 constitute what we recognize as ordinary 

 matter. Where they exist there is a local 

 deficiency of mass, so that matter is less 

 dense than its surroundings; and this, as 

 Reynolds has said, is a complete inversion 

 of the ideas which we now hold. Matter is 

 measured by the absence of the mass which 

 i^ needed to complete a normal piling of 

 the grains in the medium. In other words, 

 it might be defined as the defect of the 

 universe. The 'singular surfaces' already 

 mentioned are molecules, which may cohere, 

 but can not pass through one another, and 

 they preserve their individuality. Possibly 

 I may misapprehend this theory, for it 

 has been published in a most concise form, 

 and the reasoning upon which it rests is 

 not given in detail. I can not criticize it, 

 but I may offer some suggestions. If mat- 

 ter consists of waves in a universal medium, 

 how does chemical vmion take place ? Shall 

 we conceive of hydrogen as represented by 

 one set of waves and nitrogen as repre- 

 sented by another, the two differing only 

 in amplitude? If so, when they combine 

 to form ammonia there should be either a 

 superposition of one set upon the other, or 

 else a complex system might be found show- 

 ing interference phenomena. But would 

 not the latter supposition imply a destruc- 

 tion of matter as matter is defined by 

 theory ? Could one such wave coalesce with 

 or neutralize another? To conceive of a 

 union of waves without interference is not 

 easy, but the facts of chemical combination 



nuist be taken into account. When we re- 

 member that compounds exist containing 

 hundreds of atoms within the molecule, we 

 begin to realize the difficulties which a com- 

 plete theory of matter must overcome. 

 Chemical and physical evidence must be 

 taken together ; neither can solve the prob- 

 lem alone. At present, the simplest con- 

 ception for the mind to grasp is that of an 

 aggregation of particles. Beyond this all 

 is confusion, and mathematical devices can 

 help us only a little. In speaking thus I 

 assign no limit to the revelations of the 

 future ; some theory, now before the world, 

 may prove its right to existence and sur- 

 vive; but none such, as yet, can be taken 

 as definitely established. The theory which 

 stands the test of time will not be a figment 

 of the imagination; it must be an expres- 

 sion of observed realities. But enough of 

 speculation; let me, before I close, say a 

 few words of a more practical character. 



Dalton's statue stands in Manchester, a 

 fitting tribute to his fame. But it is some- 

 thing which is finished, something on which 

 no more can be done, something to be seen 

 only by the few. As a local memorial it 

 serves a worthy purpose, but Dalton's true 

 monument is in the set of constants which 

 he discovered, and which are in daily use 

 by all chemists throughout the world. 

 Here is something that is not finished ; and 

 here Dalton's memory can be still further 

 honored, by good work, good research, 

 honest eft'orts to increase our knowledge. 

 We have seen that the atomic weights are 

 the fundamental constants of all exact 

 chemistry, and that they are almost as 

 important also to physics; but the mathe- 

 matical law which must connect them is 

 still unknown. Every discovery along the 

 line of Dalton's theory is another stone 

 added to his monument, and many such 

 discoveries are yet to be made. 



What, now, is needed? First, every 



