138 BOARD OP AGRICULTURE. 



subject, viz: "The Influence of Forests upon Climate," would 

 require more time than can be devoted to it, when incidentally 

 treated as a single point in a lecture already too long protracted, 

 and to do it is entirely foreign from our present purpose. 



It should be stated, however, in a single brief sentence, that 

 while forests may not sensibly effect the mean temperature of the 

 globe or the total quantity of precipitation, they unquestionably 

 do promote the frequency of showers and equalize the distribution 

 of rain through the different seasons. 



The subject of the proper distribution of forest trees, in their re- 

 lation to climate, may well engage the attention of the agricultu- 

 rist, for although, in the main, his success depends upon the 

 action of forces which he cannot control, the distribution of mois- 

 ture is dependent upon conditions which he may determine, to a 

 limited extent, according to his will. It remains for us, ladies 

 and gentlemen, to consider the surface of the globe with reference, 

 to the character of rainfall ; and for this purpose the globe may be 

 divided into regions of periodical rains, regions of frequent rains, 

 and rainless regions. 



The periodical rains prevail principally within the tropics, more 

 accurately within the bolt of the trade winds ; and within this 

 belt there is one rainy and one dry season in the course of the year, 

 the rainy season prevailing in the northern hemisphere, when the 

 sun is north of the equator, and the dry season in the northern 

 hemisphere when the sun is south of the equator. Over certain 

 portions, however, of the torid zone, there are two rainy and two 

 dry seasons. That portion known as the equatorial calm belt, is 

 a region of almost constant precipitation. It sways north to 12° 

 north of the equator, and south to 50° south of the equator. This 

 belt is some 6° in -width. As this moves north of the equator 

 with the sun, it pours down volumes of rain upon the region over 

 which it passes ; and then returning witli the sun, it pours down 

 again its buixlcn of rain, so that any locality over Avhich it twice 

 passes is twice visited by a rainy season, and hence has two rainy 

 and two dry seasons. But, for the most part, in the ton-id zone, 

 there is a single rainy and a singlr; dry season, and during the 

 former, the entire rain for the year falls. The rainy season in the 

 northern hemisphere extends over a period of about five months, 

 commencing perhaps with April. Tlic character of a tropical 

 rainy day is (Mitircly dilVeront from a rainy day in our latitude. 

 In general, the sun rises clear in the morning ; about ten o'clock 



