Retrospective Criticism. lOS 



Both these motions are very distinct, though they are only varied ex- 

 hibitions of one very simple cause ; viz. the necessary circumstance that 

 every body which performs an orbit, as a consequence turns once on its 

 own axis. The earth does so, and thereby gains on its own absolute 

 orbit a space equal to its own circumference, adding a forty-seventh for the 

 moon ; and arrives at its nodes in the equator so much sooner every year 

 than in the preceding, thereby creating the exact precession of the equi- 

 noxes. The same advance of the stars then carries forward the place of 

 the apses by a proportionate quantity, insomuch that the earth's circum- 

 ference +:jV fo^ the moon, is an exact mean proportional of the other two 

 quantities. The times are 20,931, 23,190, and 25,868 years ; the angles 

 50- r^, 55-69'", and 61-9''; and the miles in space, 23,317, 25,426, and 

 27,724 ; whence it appears the sun's mean distance is 93,820,000 miles. 



With reference to the detailed inferences of Sir John, and his friend 

 Guesney, the whole is a whimsical error, arising from globe-makers locat- 

 ing an ecliptic for the practical purpose of determining declination ; but 

 the ecliptic of our terrestrial globes is not the ecliptic of nature, which 

 having no terrestrial locality, all the deductions of those gentlemen afe 

 gross errors. 



When astronomers say the pole of the equator goes round the pole 

 of the ecliptic, they indicate no change in the oblique relations of the 

 equator and ecliptic, but merely refer to the succession of the constella- 

 tions by the precession or falling back of the nodes. This motion has no 

 physical effect, because it is of no consequence whatever whether one 

 constellation or another is vertical at the equinoxes j but the progression 

 of the line of apsides has physical effects, because it changes the declina- 

 tion of the aphelion and perihelion points by 47°, and of course the direc- 

 tion of the least and greatest action and reaction. 



If we want to know why there are tropical productions in northern 

 climates, more than currents would warrant, we seem to have a cause in 

 the narrowing of the obliquity, at the rate of a minute of a degree in 120 

 years, or a degree in 7200 years. If, then, this law is constant (but I sus- 

 pect it is a decreasing series), 144,000 years would extend the tropics to 

 the Alps, and 216,000 years would extend them to Liverpool; since 

 which there would have been ten revolutions of the line of apsides, or 

 transitions of the ocean from one hemisphere to another. 



The cause of the inclination of the axis of a planet to its orbit is the 

 inequality of its solid masses, the sphere being made up by the waters, 

 but not the density, and the axis passing through the centre of density. 

 The diminution arises from the constant force tending to bring the equa- 

 tor into the plane of the orbit motion, which is assisted by the action of 

 water, air, &c., on the solid masses. 



The whole of the celestial phenomena, as I have shown in every instance, 

 are strictly mechanical, and subservient to the ordinary laws of mechanics, 

 without any attraction, gravitation, or other superstitious fancies : but my 

 present purpose is to rescue myself from the mistakes of Sir John Byerley 

 and M. Guesney. They could not have read the essays which they 

 quote, and probably have not seen my protest and supplement. I am. 

 Sir, yours, &c. — 7^. Phillips. 



" Wilson, the Ornithologist,'' did not die " a short time since," as stated in 

 your last (Vol. IV. p. 558.), but in 1809. — J. Rennie, LcCy Kent, Nov. 3. 

 1831. 



Mr. Alexander Wilson was born in Renfrewshire, Scotlahd, on the 6th 

 of July, 1776; emigrated to the United States in the year 1794, and died 

 in Philadelphia, of the dysentery, Aug. 23. 1813, aged 47. — John Perry. 

 Manchester, Nov. 23. 1831. 



[The first correction dates Wilson's death 1809 ; the latter, 1813: which 

 is right ?] 



H 4 



