M. BECQUEREL, ON THE CLIMATIC EFFECTS OF FORESTS. 311 



The climate of a country, according to M. Humboldt, is the combina- 

 tion of calorific, aqueous, luminous, aerial, electrical, and other phe- 

 nomena, which fix upon a country a definite meteorological character 

 that may be different from that of another country under the same lat- 

 itude and with the same geological conditions. According as one or 

 another of these phenomena predominate we call the climate warm, cold, 

 or temperate, dry or humid, calm or windy. 



We always regard heat as exercising the greatest influence, and after 

 this the amount of water falling in different seasons of the year, the 

 humidity or dryness of the air, prevailing winds, number and distribu- 

 tion of storms through the year, clearness or cloudiness of the sky, the 

 nature of the soil and the vegetation which covers it, and, according as 

 it is natural or the result of cultivation. The following questions arise 

 for consideration : 



1. What is the part that forests play as a shelter against the winds 

 or as a means of .retarding the evaporation of rain-water? 



2. What influences do the forests exert, through the absorption of 

 their roots or the evaponation of their leaves, in modifying the hygro- 

 metrical condition of the surrounding atmosphere ? 



3. How do they modify the temperatures of a country"? 



4. Do the forests exercise an influence upon the amount of water fall- 

 ing, and upon the distribution of rains through the year, as well as upon 

 the regulation of running waters and springs? 



5. In w hat manner do they intervene in the preservation of moun- 

 tains and slopes'? 



6. Do the forests serve to draw from storm-clouds their electricity, 

 and by thus doing diminish their eff'ects upon the neighboring regions 

 not wooded ? 



7. What is the nature of the influence that they may be able to ex- 

 ercise upon the public health ? 



From these questions we may see what questions we must solve be- 

 fore being able to decide as to the influence that the clearing off' of 

 woodlands may exercise upon the climate of a country. First of all, we 

 should know the geogra])hical position of the given country, its geolog- 

 ical condition, its latitude, its proximity to or distance from the sea, the 

 nature of its soil and subsoil, as whether pervious or impervious, cal- 

 careous or argillaceous. All of these embrace elements that we must 

 take into consideration. These questions cannot be solved a priori, and, 

 with some exceptions, they demand a i)articular examination, special 

 study and experiments, without which we run the risk of expressing 

 opinions not in accordance with those of other scientific men who, be- 

 ing placed at another point of view may have taken but a part of the 

 question. We will now proceed to give our proofs : 



The action of the forests upon the climate of a country is very com- 

 plex, for it depends : 



(1) On the extent, elevation, and nature of the soil and subsoil; 



(2) On the aspect, in its relation to warm or cold, or to damp or dry 

 winds; 



upon tlio climate of a country, presented with him an engaging theme of observation, 

 and became the subject of elaborate essays. For more than forty years an active 

 member of the French Academy of Sciences, the Comptes Eevdm of that body afiford evi- 

 dence of his diligent and approved labors, and a record of their progress. He was, 

 besides, the author of a special work upon the influence of forests upon climate. He 

 died January 18, 1878, in the ninetieth year of his age. The article here given, em- 

 bodies the ripe experience of a long life devoted to scientific researches, aud is an ad- 

 mirable example of logical conclusions drawn from carefully observed facts. 



