44 On the supposed Change 



From these observations, it results that in winter the 

 earth of the forest is seven degrees warmer than the open 

 field ; and in summer, it is, on an average, from May 23 

 to August 31, 9 1-4 degrees colder — and on an average, 

 from May 23 to October 1, 8- 1-4 degrees colder. That 

 is, the vibrations in the forest temperature of the earth 

 are between 39° and 58° — only 19 degrees of diiference 

 between winter and summer — while the vibrations in the 

 temperature of the open country, are between 32, or 

 frost, and 68 — making a difference of 36° between win- 

 ter and summer. 



The vibrations of the temperature of the air, are more 

 considerable ; but it is an unquestionable fact that they 

 are much greater in an open country, than in a forest j 

 and so far is it from truth, that the clearing and cultiva- 

 tion of our country, has moderated the rigor of our cold 

 weather, that the cold of our winters, tho less steady, has 

 been most sensibly increased. There is not a greater 

 amount of cold during the winter,' but the cold at times 

 is more severe than before our counriy was cleared. 

 The difference is so sensible, as to be a subject of popu- 

 lar remark among aged people. 



Another effect of clearing the country is to distribute 

 the cold of the year more unequally : hence fruits are 

 more exposed to spring frosts. This is a most serious in- 

 convenience in Europe, and is becoming so in America. 

 The reason of variable and late springs is obvious. While 

 the earth is covered with wood, it is never froze, but as 

 soon as the snow is dissolved in spring, vegetation begins. 

 In an open country, after the snow is melted, the earth is to 

 be thawed ; and the heat of the air for two or three weeks, 

 is incessantly absorbed by the earth and water, while the 

 frost is dissolving. Hence the heat of a warm day in 

 spring is speedily absorbed, and cold succeeds. This 

 alternation must continue, till the earth is warmed. If 

 the w^inter temperature of the earth in a forest is 39° and 

 that of the open country 32, we may easily conceive 

 what an immense quantity of heat it must require to raise 

 the temperature of the open field to that of the forest. It 

 must demand nearly all the heat excited by the solar rays 

 In Aprilj so that in our open country, the earth is proba* 



