PERIODICITY OF GOOD AND BAD SEASONS. 83 
GREAT FROSTS. 
Another interesting series of phenomena connected with 
droughts I find in the great frosts of Europe—the absence of 
cloud in these seasons, due to the dryness of the air, permits of 
extreme radiation at night, and hence great cold is frequent in 
drought winters, as heat of unusual severity is experienced in the 
summers, and it is another proof of the hold these drought periods 
have on the weather. But let us turn to the lists of the great frosts 
of Europe, collected by the celebrated astronomer Arago—they 
were not collected for the purpose I am going to use them, but he 
selected all of them from ten centuries of European records—as 
there are only sixteen in a thousand years, it is safe to assume 
they were of exceptional severity; and they are so beyond 
question. Our present purpose with them, however, is to see 
whether they support in any way our theory.—Eleven of them fall 
directly into the A drought, three of them fall directly into the 
D Drought, and three into one of the minor droughts lettered E. 
806, the Rhone was frozen over, (end of a long’A drought) 
833, the Po was frozen over from Cremona to the sea (D) 
1234, loaded waggons crossed the Adriatic on ice in front of 
Venice (E) 
1305, all the rivers of France were frozen (D) 
1324, people travelled from Denmark to Lubeck and Dantzic on 
the ice (D) 
1334, all the rivers in the South-east of France and all those of 
Northern and Central Italy were frozen and the frost 
lasted in Paris two months and twenty days (A) 
1468, it was necessary to break up the wine in Flanders with 
hatchets in order to serve it out to the soldiers, owing 
to the intense cold (A) 
1544, the wine in France frozen; had to be broken up before 
issue to the soldiers (A) 
1594, the Mediterranean was frozen over from Marseilles to 
Venice (E) » 
1657, the Seine was completely frozen over (A) 
