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their size, distance, and rotation. Jupiter, the largest planet 
in the system, rotates in less than ten hours, whilst Mars, a 
comparatively small body, occupies upwards of twenty-four 
hours in his rotation. 
The following table shows the relative rates of rotation of 
the seven principal planets : — 
Hrs. nrins. sec. 
Mercury 24 5 28 
Venus 23 21 21 
Earth 23 56 4 
Mars 24 37 22 
Jupiter 9 55 26 
Saturn 10 29 17 
Uranus 9 30 ? Supposed. 
The sun, the central luminary of the system, also rotates 
on his axis, and in a period of 607 hours 48 minutes. 
The object of the present paper is to offer some ideas 
connected with the rotation of all these bodies, and to con- 
sider the conclusions which have been apparently rather 
hastily made, in reference to the cause and continuation of 
the same movement. 
At the present time it is acknowledged that all the before- 
mentioned planets do really rotate. We know the fact, but 
beyond this we have made no step, and to us the rotation of 
a planet is like an eclipse to a savage, — an event which he 
knows does occur, but of the cause of which he is ignorant. 
It is not unusual, even in the present age, to find minds so 
constituted that when they are incapable of explaining a 
succession of effects, they at once leap from the observed fact 
to the Great Primal Cause, and thus as the savage thinks that 
he explains an eclipse by intimating that it is the effect of 
the Great Spirit's anger, so, e^eu to the present day, the 
rotation of the planets is supposed to be accounted for, by 
asserting that they were all spun upon their axis like peg 
tops, and by " Divine Energy," at the creation. It is 
certainly very difficult to find any evidence upon which this 
