E. P. Culverwell^Theory of the Ice Age. 9 



in the meridian of Greenwich, and a mean of 25° F. in the central 

 meridians of the American and Asian continents ; in other words, 

 the midwinter temperature of 54° N. is at present about 5° F. lower 

 than that of 50° N. in the continents, or, in the meridian of Green- 

 wich, about 3° F. lower. (This is, of course, taking the average rate 

 of fall between 50° N. and 70° N.) But the present midwinter 

 temperature of lat. 54°, as directly dependent on sun-heat, has been 

 shown to be lower than that of lat. 50° was in the epoch of great 

 eccentricity. Hence the temperature of lat. 50° in the supposed 

 Glacial epoch cannot, so far as direct sun-heat is concerned, have 

 been as much as from 3° F. to 5° F. lower than its present tempera- 

 ture. Similar reasoning applies to the other latitudes. 



Thus the conclusion is that the lowering of midwinter temperature 

 from 50° N. to 70° N. due to diminshed winter heat in the epoch of 

 great eccentricity cannot have been as much as from 3° F. to 5° F. 



Another way to look at it is, that the midwinter sun-heat 

 temperature of England, which is included between the parallels 

 of 50° and 55°, cannot have been as low as that of the region 

 from York to the Orkneys is now. 



Thus the foundation of the astronomical theory breaks down 

 completely. It requires us to suppose that the same quantity of 

 sun-heat as that which now, falling on Yorkshire, gives us a mild 

 and equable climate, will, if it falls on Cornwall, produce an Ice 

 Age ; or again, that if the present winter sun-heat at Oxford were 

 to be reduced to the amount which now falls at Melrose Abbey, such 

 deluges of snow would cover Oxford that a summer heat far greater 

 than that noio received there would be unable to melt it, so that 

 from year to year so great an accumulation of snow would result 

 that the Gulf Stream would be turned back to the Southern 

 Hemisphere. Observe, a summer heat far greater than that now 

 received at Oxford; for, in the 166 days of the short hot summer 

 of great eccentricity, Oxford would receive as much summer heat 

 as is now received in an equal time by latitude 35°, say by Tangier 

 or Algiers (see a paper in the Phil. Mag. of December, 1894). 



But it is unlikely that there was any fall whatever in midwinter 

 temperature in Great Britain during the epoch of great eccentricity ; 

 for, as we have seen, that temperature depends very greatly on the 

 heat received from the Gulf Stream. Now, between the Azores and 

 Ireland, the Gulf Stream is known to travel at the rate of about 

 3-9 miles per day, or 10 degrees in six months. Therefore, the 

 waters whose warmth in winter keeps our climate so temperate, 

 depend for a great portion of that winter warmth on the summer 

 sun-heat received at a point 10 degrees to the south-west on their 

 path ; and this, as I have said, was far greater in the epoch of 

 great eccentricity. 



The numbers I have given all relate to the greatest possible 

 eccentricity of the orbit. If we apply them to the considerable 

 eccentricity of about 100,000 years ago, as calculated by Leverrier, 

 we must reduce them by about one-fourth part. 



(D) With the disappearance of (C), this argument also disappears. 



