ARTICLES 60 1 



accordant with it is a fact worthy of consideration, since the 

 formula is based purely upon a mathematical development of 

 the collected results of observations and is not founded upon 

 a single simple idea such as Drayson's 'true centre of polar 

 motion,' and it should therefore be admitted as inferential 

 evidence of value." 



• 



Finally in 1906 an astronomer, G. E. Sutcliffe, wrote a 

 pamphlet which showed that Laplace had made an error be- 

 tween a + sign and a — sign, which has vitiated the whole 

 of his calculations, putting him out of court in the matter of 

 the invariable plane. 1 These calculations are all the armoury 

 that astronomers had left to them wherewith to explain the 

 present decrease in the obliquity ; though it would appear 

 that quite recently another cause has been brought forward 

 to account for the decrease. This is the attraction of the 

 planets for the equatorial protuberance. To quote from 

 Pioneers of Science (Sir Oliver Lodge) : 



" Another and a smaller motion of a similar kind (i.e. to 

 the precession caused by the sun and moon) has been worked 

 out since. It is due to the unsymmetrical attraction of the 

 other planets for the same equatorial protuberance. 



" It shows itself as a periodic change in the obliquity of 

 the ecliptic." 



To this is added a footnote : 



" The two motions may be roughly compounded into a 

 single motion, which for a few centuries may without error be 

 regarded as a conical revolution about a different axis with a 

 different period, and Lieut. -Colonel Drayson writes books em- 

 phasising this simple fact under the impression it is a discovery." 



In this attempt to belittle Drayson it is interesting to note 

 the admission, for the first time, that the motion of the pole 

 may be regarded as round a different axis with a different period, 

 the sum and substance of Drayson's contention. Until this 

 century there never has been any countenance given to such 

 a statement. Precession was then always attributed to the 

 action of the planets, as well as of the sun and moon. This, 



1 Sutcliffe further stated that the very theory on which the calculation was 

 founded showed, when tested by spherical trigonometry, that the obliquity should 

 —agreeably to the theory— be increasing, instead of diminishing, as it actually is. 

 The pamphlet entitled A Gigantic Hoax can be seen at the British Museum. 



