Lectures on astronomical theories . strated theory. Of what character is thealleged demonstration ? Before replying to this ques-tion I will endeavour to put distinctly before you themeaning which those who uphold the theory attachto the term aberration, and the precise nature of theeffect which they denote by that expression. As I, formyself, entirely reject the theory, it will be preferableto take the statement of the doctrine in the words of anacknowledged authority amongst astronomers, the lateSir John Herschel. 20 ABERRATION. HerscJieVs Outlines of Astronomy,^ page 210. (329.) Suppose a s
Lectures on astronomical theories . strated theory. Of what character is thealleged demonstration ? Before replying to this ques-tion I will endeavour to put distinctly before you themeaning which those who uphold the theory attachto the term aberration, and the precise nature of theeffect which they denote by that expression. As I, formyself, entirely reject the theory, it will be preferableto take the statement of the doctrine in the words of anacknowledged authority amongst astronomers, the lateSir John Herschel. 20 ABERRATION. HerscJieVs Outlines of Astronomy,^ page 210. (329.) Suppose a shower of rain to fall perpendicularlyin a dead calm; a person exposed to the shower, whoshould stand quite still and upright, would receive the dropson his hat, which would thus shelter him; but if he ranforward in any direction, they would strike him in the effect would be the same as if he remained still, and awind should arise of the same velocity, and drift themagainst him. Suppose a ball let fall from a point A, above. ^^Sf ^Q a horizontal line EF, and at B were placed to receive it theopen mouth of an inclined hollow tube PQ; if the tubewere held immoveable, the ball would strike on its lowerside; but if the tube were carried forward in the directionEP, with a velocity properly adjusted at every instant tothat of the ball, while preserving its inclination to thehorizon, so that when the ball in its natural descent reachedC, the tube should have been carried into the position RS,it is evident that the ball would, throughout its whole descent, be found in the axis of the tube; and a spectatorreferring to the tube the motion of the ball, and carriedalong with the former unconscious of its motion, wouldfancy that the ball had been moving in the inclined direc-tion RS of the tubes axis. ABERRATION. 21 (330.) / Our eyes and telescopes are such tubes. Inwhatever manner we consider light, whether as an advanc-ing wave in a motionless ether, or a shower of atoms travers-i
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