997 



'v.--^ i 



We may likewise find reason to think, from tfie action 

 of Jupiter on the eavth, that the earth's revolution round 

 its axis, continually becomes more and more rapid. For 

 the force of Jupiter so accelerates the motion of the 

 earth round the sun, that tlie diminution of the years 

 would be sensible, it' the diurnal motion had not been 

 accelerated nearly in the same proportion. 



It is another observation of astronomers, that the sun 

 does not shine as long on one side the line as on the 

 other : that he stays longer in the six northern shins, 

 than in the six southern : so much longer, as to make 

 no less a difference, than that of nine days. How is 

 this I Did the earth always obvert her northern hemis- 

 phere to the sun so much longer than the southern ? Or 

 lias she gradually warped so much to one side, in a course 

 of near 6*000 years! 



But over and above the sun's motion round his own 

 axis, in 25 days, 15 hours, he has another motion. There 

 is a certain point, which is the true or common centre of 

 all the planetary motions, not quite a semi-diameter of 

 the sun distant from its centre. About this point, the sun 

 and all the planets move ; but in what time is uncer- 

 tain. 



9. Let us consider more closely, the advantages arising 

 to us by the rotation of the earth about its own axis. 

 We are so made, that once in sixteen, or twenty hours at 

 most, we require a time for relaxation. And generally 

 in healthful people this time is pretty equal, between six 

 and eight hours. The storehouses of our spirits, will 

 not permit a longer application than twenty hours, with- 

 eut injury to our constitutions. And at least six hours 

 are required to rill them nsrain. 



It was likewise necessary that the air should be cool 

 and temperate during the time of this rest ; for we ge- 

 nerally find those that sleep while the sun is above the 

 horizon, the worse for it, the sun and the heat exhaling 

 the natural perspirations too violently, and raising too 

 quick -a motion in the blood. And though we- generally 

 L 5 



