396 



SCIENCE. 



[N. S. Vol. I. No. 15. 



flecked with, barely discernible patches of 

 light; he puts together these trembling 

 nebulae, as the dismembered parts of a puz- 

 zle panorama of the heavens ; and out of 

 them all, triumphant over time and space, 

 he constructs a nebular theory of the -sdsible 

 universe. He thus concludes that the vari- 

 ous bodies of the solar system " once formed 

 parts of the same undislocated mass ; that 

 matter in a nebulous form preceded matter 

 in a dense form; that as the ages rolled 

 away, heat was wasted, condensation fol- 

 lowed, planets were detached, and that 

 finally the chief portion of the fiery cloud 

 reached, by self-compression, the magnitude 

 and density of our sun " (Tyndall). 



On the one hand, the telescope and spec- 

 troscope are aids to the imagination in 

 penetrating the almost inscrutable mysterj^ 

 of the skies ; on the other, the microscope 

 enables it to descend somewhat into the no 

 less limitless underworld, and to sink the 

 exploring plummet to depths as far removed 

 from the field of the microscope as the celes- 

 tial boundaries are beyond the vision at- 

 tained by the telescope. 



How wonderful, also, is the ethereal me- 

 dium which man's imagination has con- 

 structed, the vehicle of the energy wafted 

 to us from sun and stars ! To the mental 

 vision this medium fills all space and quiv- 

 ers with radiant energjr — that winged Mer- 

 cury, bearing messages to man from all the 

 worlds on high. Even electrical and mag- 

 netic phenomena are utterly inexplicable 

 without it. The imagination of Faraday, 

 of Maxwell, and of Hertz, has woven out of 

 it a texture of lines of electric and magnetic 

 force, which are as real to the electrician 

 as the machines and conductors which he 

 mantles with them. Every conductor con- 

 veying a current, every permanent or elec- 

 tromagnet, is surrounded with its system of 

 lines of force in the ether. And when an 

 alternatiag current traverses a conductor 

 these lines of magnetic force are projpagated 



outward from it in waves which spread with 

 the velocity of light. In fact, thej' are iden- 

 tical with light objectively, except in point 

 of wave-length. Thus the theory, imagined 

 by Maxwell with the insight of marvelous 

 genius, and confirmed later by the classical 

 experiments of the lamented Hertz, is now 

 accepted doctrine by physicists the world 

 over. The existence of the ether is now 

 seen to be a necessary consequence of Eoe- 

 mer's discovery in 1676 of the finite speed 

 of light. For the transmission of light is 

 the transmission of energj^; and a medium 

 of transmission is a necessary postulate as 

 the repository of this energy during the 

 time of transmission. N"ewton imagined the 

 light-giving body projecting minute parti- 

 cles, or corpuscles, through space and car- 

 rying their energy with them as a bullet 

 carries its energy to the mark. These en- 

 tering the eye excite vision by impact upon 

 the retina. But Newton's corpuscular the- 

 ory failed because of its final complexitj' 

 and the crucial test applied to it by the 

 great experimenter, Foucault. 



The undulatory theorj^, on the other 

 hand, requires a continuous medium, and 

 the energy is handed along from particle to 

 particle as an undulation. In this way 

 energy is conveyed bj^ sound and by water- 

 waves across the surface of the sea. Ac- 

 cording to this theory, a luminous body is 

 the center or source of a disturbance in the 

 ether which is propagated in waves through 

 space. They are electromagnetic in origin, 

 travel with the velocity of light, and en- 

 tering the eye excite the sense of vision. 

 Thus far have we been helped along by the 

 imagination of genius and the contributory 

 aid of experiment. Mean and unfi-uitftil 

 indeed is the science which has not been en- 

 riched, extended and vivified bj^ the scien- 

 tific imagination. Where dull reason halts 

 and the understanding is confounded by 

 appalling obstacles, imagination overleaps 

 them all and the barriers are dissolved 



