532 Mr. C. Brooke on the Nature of JEther. 



ordinary matter, amenable to our senses, as well as to the universal 

 law of gravitation, must be occupied by a strange and anomalous 

 form of matter amenable to neither ? Probabilities appear to negative 

 this question. But it will be immediately asked, how can sether be 

 imagined to avoid pervading our atmosphere and all other kinds and 

 forms of matter ? Simply by ascribing to it a property of non-misci- 

 bility with our atmosphere, like oil with water — a quality not entirely 

 adverse to experience, nor repugnant to reason. The question then 

 naturally arises, what becomes of the waves of heat and light when 

 they reach our atmosphere? and is ordinary matter sufficient and 

 effectual for their transmission ? This question can be answered only 

 from analogy, which appears to infer an affirmative. 



That sound-waves are transmitted by air, and not by interstitial 

 sether, is unquestionable ; and if air be capable of transmitting 

 25,000 vibrations in one second, it would probably be difficult to 

 assign any valid reason why the same medium is incapable of trans- 

 mitting the far more rapid waves of heat and light ; and if capable, 

 then where lies the necessity for assuming the presence of another 

 medium? 



Again, the refraction of sound, as demonstrated by the experi- 

 ments of Hajech and Sondhaus (583,564), is in exact accordance with 

 the laws hitherto assigned to the refraction of light and heat. But 

 the phenomena of the refraction of light require a very forced ad- 

 dendum to the interstitial-aether hypothesis, namely, that the elasti- 

 city of the sether is dependent upon that of the medium which it pervades 

 — an unprecedented influence of one kind of matter on other merely 

 contiguous matter. And it appears that the velocity of sound in solids 

 and liquids is much greater than in air (545); in water it is nearly 

 5000 feet, and in iron nearly 17,000 feet in one second: is there, 

 then, any known fact whatever that tends to assign a limit to the 

 possible velocity of transmission of wave-motion through these and 

 other material media? if not, then the presence of sether, as gene- 

 rally assumed, cannot be deemed essential to the transmission of 

 light ; and if not essential, why should the old hypothesis be enter- 

 tained? 



" Nee Deus intersit nisi dignus vindice nodus 

 Incident." 

 Moreover Professor Tyndall, to whom the progress of Dynamical 

 Physics is indebted for many laborious and important researches, 

 has observed that in various kinds of wood there is a remarkable 

 harmony between their respective conductivities for sound and heat 

 in three mutually perpendicular directions, namely, longitudinal, 

 transverse-radial, and transverse-tangential (546). Now, although 

 there is certainly no direct analogy between the conduction of heat 

 and the radiation of light, beyond that of their common dynamical 

 origin, a much closer analogy may nevertheless be traced through 

 the phenomena of phosphorescence, fluorescence, and calorescence. 

 Is it, in fact, generally believed that the transmission of heat-motion 

 is effected by interstitial sether, and not by the molecules of the 

 medium itself? If not, why should a hypothetical medium be as- 



