MENTAL EVOLUTION 133 



. . . inundated the city of Mayence and the cathedral 'usque ad 

 cingulum hominis.' The walls of Cologne were flooded so that 

 they could be passed by boats in July." This occurred also in 

 1374 in mid-February, which is an unusual month for such dis- 

 asters. "Again in other years the drought was so intense that 

 the same rivers, the Danube, Rhine, and others, nearly dried up, 

 and the Rhine could be forded at Cologne. This happened at 

 least twice in the same century. There is one exceptional summer 

 of such evil record that centuries afterward it was spoken of as 

 *the old hot summer of 1357.' " 



Pettersson also states that on the coasts of the North and 

 Baltic seas not less than nineteen storms "of a destructiveness 

 unparalleled in later times are recorded from the fourteenth cen- 

 tury." The coastline of the North Sea was greatly altered by 

 these storms. Thus on January 16, 1300, half of the island of 

 Heligoland and many other islands including Borkum were en- 

 gulfed by the sea. So great was the destruction of sea-coast 

 villages that this storm is known under the name of "the great 

 man-drowning." Again in 1304, on November 1, the Island of 

 Ruden was torn asunder from Rugen by the force of the waves. 

 Many other similar disasters occurred, almost always in the cold 

 season. 



From this assemblage of facts, which might be greatly increased, 

 it appears that the fourteenth century, especially its early part, 

 was marked by notable storminess in both of the belts where 

 storms now increase during times of many sunspots. As to v,^hat 

 was happening in the sun at that time our knowledge is extremely 

 scanty. European records of sunspots begin only in 1610, and 

 are accurate only since 1755. In China imperfect records are 

 available almost as far back as the time of Christ. Of course 

 these include only years when the spots were visible to the naked 

 eye. Moreover, since there was no official agency for making 

 observations, it must often have happened that great disturbances 

 passed unrecorded because no one happened to set down the fact 



