SIGNS OF RAIN. 85 



wind is, generally speaking, the driest by the hygro- 

 meter, unless at that particular season when the evapo- 

 ration on the sandy plains of Germany has become a 

 maximum from the action of the summer heat, a 

 mantle of cloud upon a high mountain, as far to the 

 westward as it can be seen, is a much more certain 

 prognostic of rain than any barometer. We have often 

 had occasion to notice the progress of this change : 

 after weeks of drought, the sky began to be overcast, 

 but along with that the drought became more keen and 

 constant, so that there was no dew ; the channels of 

 the rills were dry and champed, and the small trick- 

 lings and oozing in those places which yield a little 

 water, but cannot be called springs, wholly disap- 

 peared ; so did the frogs, the slugs, and all other 

 creatures that suffer much from excessive evaporation. 

 Gradually the atmospheric haze became thicker and 

 thicker, and for a time the east wind appeared to 

 strengthen with it. That, however, only increased the 

 collision and condensation, and the consequent satura- 

 tion of the current from the east. At last the wind 

 from that point fell nearly to a calm, the trickling 

 water again began to show itself, and the frogs to leap 

 about in the evening. The old people (for they were 

 naturalists in their way) knew the sign, and rejoiced 

 that their crops were not to be parched up. " It is 

 the earth," said they, in their homely phrase, " coming 

 out to meet the rain." Next day the mantle was on 

 the mountain, at nightfall it began to patter, and ere 

 morning the earth was refreshed by a copious flood. 



It is only in the months of April, May, and June, 

 when the evaporative power of the air, at least on the 



