184 METEOROLOGY. [July 



of this is the Lenkoran forest on the west coast of the Caspian, 

 where the vegetation is more luxuriant than in any other part of 

 Europe, yet very little rain falls in summer, but the rainfall in 

 autumn and winter is great. The water is stored up by the 

 forest, and is used in evaporation during the heat of summer. 

 Humidity of the atmosphere, however, is not inconsistent with 

 a high temperature, as the Eed fSea shows ; but in forests the 

 humidity is due to the evaporation of the leaves — in other words, 

 to a process by which heat is converted into work, and hence the 

 coolness. Herr Woeikof then endeavours to ascertain the influence 

 of forests on the climatic conditions of their neighbourhoods in the 

 western parts of the Old World, between the 38th and 52nd 

 degrees N. latitude, the places selected being in all cases in the 

 open. Thus for the 52nd degree eight stations are taken between 

 Valentia in Ireland on the west and the Kirghiz steppes on the 

 east; for the 50th, Guernsey on the west, Semipalatinsk on the 

 east, and thirteen stations, and so on for each two degrees of 

 latitude to 38°. The general result of the observations in fifty 

 stations in six different degrees of latitude is that in Western 

 Europe and Asia large forests have a great influence on the 

 temperature of places near them, and that by their influence 

 the normal increase of temperature as we travel eastward 

 from the Atlantic Ocean to the interior of the continent is not 

 merely interrupted, but they give places far removed from the 

 coast a cooler summer than those actually on the sea. A striking 

 example of this is Bosnia. An examination of the statistics shows 

 (1) that in Bosnia the summer is 2°'5 to 4°'5 cooler than in 

 Herzegovina ; (2) even on the island of Lissa, in the full influence 

 of the Adriatic Sea, the summer temperature is more than a degree 

 higher than that of Bosnia, which is separated by lofty mountain 

 ranges from the sea. Bosnia owes this comparatively cool summer 

 to its great forests, while Herzegovina is almost disafforested. To 

 sum up : forests exercise an influence on climate which does not 

 cease on their borders, but extends over a larger or smaller adjacent 

 region according to the size, kind, and position of forest. Hence 

 man by afforestation and disafforestation can modify the climate 

 around him ; but it is an extreme position to hold that by afforesta- 

 tion the waste places of the earth can be made fertile. There are 

 places incapable of being afforested, which would not give the 

 necessary nourishment to trees. — Nature. 



