74 



THOUGHTS ON THE INFLUENCE OP ETHER 



It is scarcely necessary to remark that the ether by whose agency it is proposed to ex- 

 plain the interesting phenomena alluded to in the title of this essay, is not a fluid pos- 

 sessed of the fanciful properties ascribed to it by the ancients. My only purpose in 

 dwelling upon these is to show, as I shall do presently, how such ideas have poisoned the 

 minds of modern philosophers. 



To Professor Encke is the learned world indebted, for pointing out the first rational 

 evidence of the existence of an ethereal medium, in the continually diminishing period of 

 the comet which bears his name. 



By its influence \ipon Encke's comet, the ether shows itself to be possessed of two of 

 the properties of aeriform bodies, viz., inertia and impenetrability. It would not be ad- 

 vancing too far, nor too fast into the land of speculation, to endow this fluid also with 

 gravity, elasticity, and expansibility by heat. 



The possession of the properties of gravity and elasticity leads to the conclusion that 

 the particles of ether must be collected into denser masses in the vicinity of the central 

 body of our system, than in regions remote from the sun ; and the inquiry at once suggests 

 itself, what law governs the density of the ether in the different parts of the solar 

 system ! 



In the terrestrial atmosphere, where the influence of a varying distance from the centre 

 of attraction is too small to be appreciated, and where the increase of the density near the 

 earth's surface is due almost solely to the superposition of the particles of air, we find the 

 rate of diminution of density to be in the duplicate ratio of the altitude. 



In the interplanetary spaces, the laws which determine the rate of diminution of the 

 density of the ether are more complicated. 



The ethereal pressure at any given point in the solar system, will depend not only upon 

 the quantity of ether beyond it, but also upon the power which the sun has to attract that 

 which is beyond the point in question. 



Now, either of these causes acting alone should fix the rate of diminution at the square 

 of the distance from the sun. As both of them act together, a legitimate inference should 

 be, that the density of the ether decreases as the fourth power of the distance from the 

 sun's centre. 



In considering the subject of ether, we must endeavor to guard ourselves against cer- 

 tain errors into which our daily intercourse with matter may lead us. We see, for example, 

 the collision of heavy bodies, and, as a result, the production of fragments whose weight 

 and hardness we can estimate with our hands. These arc phenomena which so vividly 

 impress our senses, that we arc apt to ignore the possible existence of matter in a form 

 which, to our sight and touch, may be inappreciable. 



It is this form of matter that now concerns us, and to give a faint idea of its tenuity, 



