286 CONTINUOUS VIBEATORY MOVEMENT OF 



movements of the .itoms of luminous bodies and tlie undulations of the ether 

 which are the consequence thereof. The hypothesis of undulations has received, 

 in recent times, tlie support of facts and of analysis to such an extent that it may 

 be re.^-arded as the true expression of a physical law, and be recognized in science 

 with the same certainty a« the theory of gravitation. How curious an object of 

 meditation is light considered as an agent producing continual modifications on 

 the earth and in the air, in organic tissues and in minerals ! In this point of 

 view, liglit appears as the effect of an initial force, capable of producing, in a 

 mediate or immediate manner, other modes of action, such as chemical and caloriiic 

 effects. 



It is generally considered that an incandescent combustible body is an assem- 

 blage of molecules undergoing separation of their constituent elements in order to 

 reunite with other molecules Vvhich they encounter in the air; that all the parts 

 of an ignited body are subjected to violent movements, and that the atoms of 

 every luminous body are in an analogous state of agitation. Atoms have the 

 facultv of transmitting their movements to the neighboring particles of the ether, 

 wdnch, in turn, communicate them to the surrounding particles, and thus these 

 movements are propagated to the greatest distances with the rapidity of lightning. 

 Thus the ether only becomes luminous because the incandescent bodies and stars 

 have arrived above the horizon and impress undulatory movements on its parti- 

 cles. It is for a like reason that at night our apartments and halls become as 

 well illuminated as by day ; when left in darkness it is only from the absence 

 of a body capable of impressing on the ether contained in the hall a movement 

 sufficiently intense to excite our visual organ. 



It is proper to reinarlc that the movement of the either impinging upon bodies 

 is calculated to impress on their ponderable atoms regular vibrations, but vibra- 

 tions more and more feeble as the distance traversed by the undulation is greater 

 and the diffusion it has undergone more considerable. Vibrations of the second 

 order by which ponderable bodies are thus animated may, in their turn, impress 

 on the surrounding ether undulations less and less intense ; by the same 

 mechanism vibrations of the third and fourth order may render objects which are 

 opaque for us visible to other more impressible beings, and, indeed, exert influ- 

 ences capable of modifying the molecular structure of solid bodies. 



If hesitation be felt in admitting these principles, let it be remarked only that 

 tfhe vibrations of a tuning-fork continue to be perceptible long after the concus- 

 sions of the bow or stick have ceased to be directly communicated; let it be con- 

 sidered, also, that when the instrument has lost the property of directly mani- 

 festing its vibrations to the ear, they do not. the less exist, and may be rendered 

 perceptible by placing it on a suitable sounding-board. It cannot then be unrea- 

 sonable to admit that bodies struck by light during tlie day should receive in 

 their atoms a corresponding vibratory movement, a mo^■ement which persists in 

 darkness and is communicated to the surrounding ether. If gypsum, the diamond, 

 and otlier bodies exposed to the solar rays acquire the property of becoming 

 visible lV)r some time in the dark, where is the explanation of this phenomenon to 

 be sought if not in the persistence of the atomic vibrations after the exciting 

 force has ceased to act"? Can any other cause be attributed to the mysterious 

 images of Moser ? Is it not probable, from these considerations, that vibrations 

 insensible to the retina of the human eye may produce an energetic action on the 

 visual organ of certain animals? It is highly probable that the antenna3 of some 

 insects receive impressions of which we have no precise idea, while these creatures 

 are insensible to the impressions which affect our organs ; their sensations, per- 

 haps, commencing at the point where ours cease. 



It is impossible to conceive at any point of our globe, which changes its posi- 

 tion at every instant in relation to the sun, the same temperature during two con- 

 secutive moments ; hence there results a continual change in the molecules 

 of all bodies. The astronomer Cesaris, by observing at several intervals the 



