702 KANSAS CITY REVIEW OF SCIENCE. 



rapid motions of the molecules, and these are the units of physical problems, 

 render them inaccessible to our grosser senses and it becomes necessary to study 

 them as best we can by the effects that they and their motions produce. By cor- 

 relating and comparing the knowledge, thus obtained, it is possible, at times, to 

 learn somewhat of the nature and conditions of the molecules themselves. Some- 

 times the result, satisfactory at first, has been found to be fallacious ; sometimes 

 it contains the elements of truth and grows. Newton, in order to account for 

 the phenomena of light, advanced the corpuscular theory — a quahtative attempt. 

 Put to the test of fact, it failed. Then Hooke and Huyghens put forth another 

 qualitative hypothesis — the undulatory theory. Newton supposed that light con- 

 sisted of exceedingly small portions of matter sent out from a luminous body in 

 all directions and with inconceivable, though finite, velocity. The undulatory 

 theory supposes the existence of the luminiferous ether, a continuous, elastic and 

 very "subtle" medium, pervading all space. When considered casually, these 

 two suppositions seem equally improbable. But nature herself has decided be- 

 tween them. The corpuscular theory has been disproved, 'while the undulatory 

 theory, though still awaiting its ultimate and complete establishment, is steadily 

 gaining ground. 



In astronomy, the vast distances — too great to be even imperfectly compre- 

 hended, and huge masses — too large to be the subjects of experiment, render 

 progress slow and complete explanation difficult. Time is rhe chief element of 

 success, time in which the unknown laws, by their continuous action, may pro- 

 duce results that can be interpreted. As a finished example of quantitative in- 

 duction we may take the law of gravitation. Tycho Brahe and Kepler had laid 

 the foundation of facts on which it was to be built. Newton, taking these facts 

 and dealing with them in the most rigorous manner, produced the clear and 

 mathematical statement of the law. It sprang full grown from his brain. It has 

 not been changed, increased, or modified by subsequent researches. The work 

 was finished when he proved that the moon was rigorously subject to the law. 



But is seldom that a theory can be framed as completely as this when first 

 presented. Qualitative induction has its field of usefulness, and without it actual 

 progress would be slow. There are but few men that are sufficiently patient and 

 have enough faith in the future to spend their days in the laborious accumulation 

 of mere facts and figures. The work is apt to become pure drudgery unless there 

 is the impetus of comparing the facts with some hypothesis. A working hypothe- 

 sis is of itself an incentive to new work and new discoveries. It gives glimpses 

 of unexplored territory and the natural desire is to enter and investigate. Lock- 

 yer's hypothesis that the so-called elements are compound and that the real ele- 

 ments only present themselves as such under the tremendous temperatures of the 

 Sun has produced, beside the inevitable discussions, sound work and real ad- 

 vance in solar physics. Maxwell's statement of the theory of the connection be- 

 tween electro-magnetism and light has stimulated research and seems to promise, 

 in one direction at least, an explanation of that marvel of the philosophers, action 

 at a distance. Ampere's idea that magnets are but collections of currents of 



