436 Dr. Echo. Jdderin — On Variations of Climate. 



Moreover, they directly affect agriculture, particularly on the larger 

 continents. As a proof of this may be mentioned the great increase 

 in the colonization of the North-West American Continent, and the 

 increased rainfall which followed the last dry period, about 1860. 



Tbe experience of this comparatively short rainy and stormy 

 period easily explains how people assert that the climate has under- 

 gone a change in one direction, with just as much justice as other 

 people claim an opposite experience. 



Having thus explained the manner in which we may assume that 

 the climate varies periodically or regularly in a uniform or variable 

 manner in different parts of the globe, and that the period extends 

 over 36 years, it would appear from observations that we are at 

 present about the middle of this period, having entered the dry 

 span. 



We are, however, aware of other variations occupying much 

 longer periods, which may on account of this greater length exercise 

 a far larger influence upon terrestrial conditions. 



We know that Northern Europe even at a comparatively recent 

 geological period was covered with ice, like Greenland at present, 

 and was therefore at that time as uninhabitable as the latter con- 

 tinent is now ; but we know, too, that this does not indicate a 

 continuous change in one, certain direction, whereby our climate 

 should steadily become warmer and warmer or that it was equably 

 colder the further we go back in time. For various discoveries 

 made by geologists in the flora and fauna from a period far more 

 remote than the Ice Age show conclusively that at that epoch a 

 climate prevailed in Northern Europe which produced plants and 

 animals similar to those now found in the Tropics. The Ice Age 

 must therefore be considered only an accidental deviation — for 

 a comparatively short period — from the mild climate of pre-Glacial 

 time. To fix the time of this tropical climate is, we must confess, 

 impossible, but the alternating geological strata of the earth appear 

 to indicate that we have here to reckon with hundreds of thousands 

 or may be millions of years. 



That this variation in the climate may be connected with the 

 gradual cooling of the earth was formerly an accepted theory, and 

 this with greater reason as it was once assumed that this cooling 

 was general, if not for the whole earth, at all events around the 

 Poles. However, modern savants have shown that this is now an 

 untenable theory, as it has been proved that in Japan, for instance, 

 the climate was at a remote period much colder. 



At a recent meeting of the Eoyal Swedish Academy of Sciences 

 Prof. Nathorst demonstrated that the axis of the earth during the 

 geological periods in question has changed its position within the 

 body of the earth itself, and that the North Pole has approached 

 towards us, away from the Japanese side of the earth. From this 

 should have followed a variation of the Polar Meridian of places 

 upon the earth, and this seems also borne out by recent astronomical 

 observations. It has been found that the change is infinitesimal, 

 perhaps only amounting to a second per century, but this second 



