THE UNITY OF PHYSICAL SCIENCE 7 



those of four-place tables of logarithms and anti-logarithms. The 

 so-called "Constants of Nature" supplied by chemistry are, in fact, 

 known with a low degree of certainty; a degree expressed, say, by 

 three to five significant figures. A small amount of reflection, how- 

 ever, will convince one that the phenomena with which the chemist 

 has to deal are usually far more complex than those which have 

 yielded the splendid precision of astronomy, geodesy, and metro- 

 logy. Moreover, it should be observed that the certainties even of 

 these highly perfected sciences are very unequal in their different 

 branches. It appears more correct, therefore, as well as more just, 

 considering the central position it occupies and the wide range of 

 its ramifications, along with the vast aggregate of qualitative and 

 quantitative knowledge it has massed, to assert that the precision 

 of chemistry affords the best numerical index of the present state of 

 physical science. That is, when reduced to the most compact form 

 of statement, the certainties of physical science are best indicated, 

 in a general way, by a table of the combining weights of the eighty- 

 odd chemical elements. 



When one contemplates the numbers of such a table, and when 

 one adds to its suggestions those which flow from the various peri- 

 odic groupings of the same numbers, he can hardly avoid being in- 

 spired by the day-dreams of those who have looked long for the 

 atomic unity of matter. But however the grand problem which thus 

 obtrudes itself may be resolved finally, it appears certain that this 

 table must stand as one of the great landmarks along the path of 

 progress in physical science. 



It was justly remarked by Laplace in his Systeme du Monde that 

 ''L' Astronomic, par la dignit6 de son objet et par la perfection de ses 

 theories, est le plus beau monument de 1'esprit humain, le titre le 

 plus noble de son intelligence " ; and we must all admit that subse- 

 quent progress has gone far to maintain this high position for the 

 most ancient and interesting of the older sciences. One finds little 

 difficulty in accounting for the early rise of astronomical science 

 and for the universal interest in celestial phenomena. Their im- 

 manence and omnipresence appeal even to the dullest intellects. But 

 it is not so easy to account for the remarkable fact that although 

 astronomy deals chiefly with the relations of bodies separated by 

 immense distances, progress in its development has thus far been 

 at least equal to, if not in advance of, the progress of physics and 

 chemistry, which have to deal with matter close at hand. Without 

 attempting a full explanation of this fact, it may suffice to observe 

 that the principal phenomena of astronomy thus far developed 

 appear to be relatively simple in comparison with those of the other 

 physical sciences; and that the immense distances which separate 

 the celestial bodies, instead of being an obstacle to, are a fortunate 



