58 Prohahle Astronomical Causes of 



high latitudes, the two currents are by no means equal in 

 amount, so that the balance of force would go to retard the 

 earth's motion. 



These forces are, it must be admitted, most ridiculously 

 small, but even an almost infinitesimal force, acting contin- 

 ually, must ine\dtably stop a motion, however swift, and put 

 an end to a momentum, however great. There is no resource, 

 therefore, but to conclude that these respective agencies — if 

 you admit them — acting throughout countless ages, have 

 tended, and are materially tending, to bring about an utter 

 stoppage of our planet's axial revolution. 



IV. There are some few astronomical facts relative to 

 other planets of our system which may serve to throw still 

 further light upon this subject. 



The moon, which has no axial revolution, is quite 

 spherical. Seen through a telescope, too, it presents a feature 

 — for my own part I attach but little importance to the fact 

 — yet, as bearing upon the present subject, the feature is 

 rather remarkable. Near the satelhte's upper limb is the 

 great crater of Ty cho, and from this as a centre run a number 

 of radiating lines, corresponding with (supposing this crater 

 to have been once the moon's pole, when she had an axial 

 revolution like the other planets) the hypothetical star-like 

 fissures at the north and south poles of this our earth. 

 Adjacent to the space over which the rays extend is a region 

 seemingly of quiescence, and beyond is what seems to me a 

 zone in which a puckering up of the surface has taken place, 

 analogous to that supposed in the tropical regions of our 

 own globe. I lay but little stress upon this fact, and merely 

 mention it in passing and by the way. 



The surface of no other planet is thus open to telescopic 

 inspection, but there are certain physical facts connected 

 with several illustrative of the theory in a measure somewhat 

 remarkable. 



In the first place there is a very striking difierence in the 

 rate of their respective rates of axial revolution. Nearly all 

 revolve in different times, and thei^|is this peculiarit}^-, that 

 the slowest motions are just where the quickest ought to be 

 expected, and vice versa. 



Thus the Earth's period of axial revolution is twenty-four 

 hours, but that of Jupiter, a much larger planet, is only 

 twelve. Saturn, less than Jupiter, but an immense body as 

 compared with the earth, is ten and a half hours. That of 

 Mars (a planet whose diameter is half that of our own) is 



