XX.] THE MOVEMENTS OF THE EARTH. 347 



east, and, after marching across the sky in a curved path, 

 to set towards the west. Every night, too, some of the stars 

 appear, in like manner, to rise and set ; and this is what they 

 must certainly do, if, as we know to be the case, on inde- 

 pendent grounds, the earth turns round upon its axis from 

 west to east. 



Every one must have noticed in travelling by railway, that 

 if his own train is in a station, alongside of another, he con- 

 stantly fancies the other train is moving, when it is his own 

 which has gently started ; and, on looking out of the window, 

 when the train is at speed, it may be really difficult to per- 

 suade oneself that the telegraph posts, and the nearer trees 

 and houses, are not whirling past the more distant objects, 

 in a direction contrary to that in which the train is moving. 

 And although^ when one looks at the rising or the setting 

 sun, it seems contrary to the evidence of one's senses that 

 the sun is not moving and the earth is ; yet this is one of 

 the many cases, in which what is called the direct evidence 

 of the senses is nothing but a hypothetical interpretation 

 of the facts of which sensation tells us. That this appar- 

 rently obvious and natural interpretation of the fact of the 

 change of place of the sun and stars — an interpretation 

 upon which the whole human race were agreed a few cen- 

 turies ago — is wrong, and that it is the earth which rotates, 

 has long been rendered highly probable; and the experiments 

 of M. Foucault some years ago completed the proof. 



The diurnal rotation of the earth does not explain all 

 the apparent movements of the heavenly bodies. For 

 example, it is observed that the sun does not rise, day after 

 day, in exactly the same place. In mid-spjing and in mid- 

 autumn, it rises almost precisely due east; but, in midsum- 

 mer, it rises to the north of the east point of our horizon, 

 and, in mid-winter, it rises to the south of this point. The 



