VOt. XVI.3 PHILOSOPHICAL TRANSACTIONS. 409 



angle which the earth's axis maices with the plane of the ecliptic, or orbit where- 

 in she moves annually round the sun, has been without sensible change in all 

 that time ; which will be very hard to conceive, if we allow a translation of the 

 earth's poles ; for the direction of the axis being perfectly at liberty, it must be 

 purely casual, if it happen, that after such change, it make the same angle with 

 the ecliptic as before. 



A farther argument of this slowness of the change of the poles, is the lati- 

 tude of Alexandria, the habitation of those famous astronomers of antiquity, 

 Eratosthenes, Timocharis, Hipparchus, and Ptolomy, and for that reason it 

 may be concluded that this, of all the latitudes the ancients have left us, ought 

 to be one of the most correct. This by Ptolomy is said to be 30° 58' north, 

 which he uses in all his computations in his Almagest, and seems derived from 

 the proportion of the gnomon to its equinoctial shadow, as 5 to 3 ; but in his 

 geography he uses 31° just. In the year l638, the curious and ingenious Mr. 

 Greaves, when he went to visit the Egyptian pyramids, with a sufficient instru- 

 ment observed the latitude of Alexandria, and found it 31° 4', or 6 minutes more 

 than it is reputed by Ptolomy, and before him by Eratosthenes ; so that in 

 about 2000 years the latitude of Alexandria has altered only a few minutes, and 

 so few that the accuracy of the observations- of the ancients may well be 

 questioned : but both being granted, this motion will amount to no more than 

 a degree in 20,000 years. 



This is said not with intent to invalidate what Mr. Hook has, from so good 

 grounds, advanced, viz. that the ball of the earth, at least the fluids of it, being 

 necessarily of the figure of a prolate sphaeroid, or flat oval, whose shortest dia- 

 meter is the axis, and greatest circle the equinoctial ; if the poles be supposed 

 changed, the equinoctial will be so too ; and consequently the water must rise 

 and cover those parts from which the poles recede, and fall off" and leave bare 

 those places towards which the poles approach. By this means it may be ac- 

 counted for, how such strange marine things are found on the tops of hills, and 

 so deep under ground ; and scarcely any other way. But from these and the 

 like observations it will follow, that if these inundations are produced by any 

 regular motion of the poles, it would require a prodigious number of ages to 

 eflfect those changes we may be certain have been. Besides, if the access and 

 recess of the sea were after such a gradual manner, as when produced by such 

 an easy translation of the poles, as can by observation be admitted, tliose in- 

 undations could never be fatal to the inhabitants, as they would always give no- 

 tice of their coming, so that the people might provide for their safety. But 

 both sacred and prophane tradition agree, that the last great deluge was pro- 

 duced in a few days, without any previous notice ; so that it could not be ac- 



VOL. III. 3 G 



