234 WARKEN UPHAM, ESQ., ON CAUSES OF THE ICE AGE. 



Again, Mr. Upham says : 



The portion of the present cycle of variation, which is used as the basis 

 of thi:^ tlieory, seems insufficient to establish its conclusion of a wide range 

 of obliquity. 



As a geometrician, I am at once at issue with Mr. Upham. 1 

 have stated that the radius of the circle now traced by the Pole 

 is 29° 25' 47". If I were even half a degree in error, I could not 

 calculate accurately the position of a star for even ten years in 

 advance. The error would be manifest. But I, and others, can 

 now calculate for 150 years in advance to within a fraction of a 

 second. I should like to know whether Mr. Upham has formed his 

 conclusions on opinion or on calculation. If the latter, I shall be 

 happy to compare our two calculations to see who is in error, and 

 I would submit that some star, say Alpha Draconis, should have 

 its right ascension and declination taken from Bradley's Catalogue 

 of 1755, and from this one observation calculate its right ascension 

 and declination for 1850 and 1890. I can predict that if Mr. 

 Upham makes this calculation, he will soon find that the slightest 

 error in his radius will produce a considerable error in his results. 

 But we have Ptolemy's Catalogue of 140 a.d. for reference, so 

 that 1 750 years gives us a check on our work. 



Again Mr. Upham says : — 



The same arguments forbid its application to account for the Glacial 



epoch as against CroU's theory. According to General 



Drayson, astronomical conditions capable of producing an Ice Age have 

 occurred every 31,000 years. 



This may be Mr. Upham's theory, but it is not mine ; see 

 chapter 17 of my book. I fear, however, I cannot quite agree 

 with his logic. The daily rotation of the Earth fully explains 

 the rising and setting of the various celestial bodies, but it 

 fails to explain the changes in the Sun's midday altitude from 

 summer to winter. Hence we ought to reject the daily rotation 

 as an explanation of the rising and setting of celestial bodies, 

 because it fails to explain summer and winter. I will give a few 

 quotations from chapter 17 of my book. I have there pointed out 

 that the present position of the Pole of second rotation is probably 

 due to the position which the centre of gravity occupies relative 

 to the Earth's centre. I then refer to the elevation or depression 

 of land, or even of continents, causing the waters of the ocean to 

 be distributed differently from what they are at present, and hence 

 causing the centre of gravity of the Earth to slightly alter its 



