32 



From abundant- proof and many observations, as well as from the natural reasoning 

 concerning what must be the case under such circumstances, it is evident that there is 

 arising from forests a vast amount of vapour of water, which, as we hav5 seen, is the 

 lightest of vapours. This vapour will necessarily be cool, as is the forest region from 

 which it comes. 



The winds bearing moisture coming from the south will not be generally as cool. 

 These, meeting the ascending streams of cool and moist air arising from a forest region, 

 TOUst be deprived thereby of their power of holding a great part of the water they carry, 

 •which must shortly descend in rain near the place of conjunction, according to the tem- 

 perature of the approaching wind, and the amount of water it bears. 



Thus we have the chain of proof, and the direct influence of forests in securing rain 

 during summer given in its completion. Spring and summer are the seasons when the 

 internal functions of trees are in their greatest activity ; then is transpiration most active; 

 then rise from them most columns of humid air towards the clouds. Spring has not 

 so many leaves, but then the sun pierces the forest, and draws from the ground — the bed 

 of moisture, as before explained — an amount of vapour many times greater than the fields 

 can afibrd. This cool vapour, rising and meeting the south, south-east, or south-west 

 wind forms rain. And these seasons, spring and summer, are those in which rain is most 

 ■needed by the thirsty fields and the growing vegetation. This is the value of woods to 

 the farmer. 



We have now gone over the complete system of transpiration of moisture by wind 

 throughout the atmosphere from equator to poles and back to the equator again. But it 

 was also remarked that there were many important circumstances of local origin which 

 produced local results in the distribution of moisture and the arrangement of climate. To 

 us in the Province of Ontario there are existingvery important local circumstances indeed, 

 which undoubtedly have a great influence, that is to say, the presence of the great lakes. 

 Our chief reservoir of moisture, as is that of all the world, is th& equatorial ocean. But 

 our lakes also greatly help, and there is no doubt that their presence largely contributed 

 to the establishment of the splendid forests we have destroyed, and to the accumulation 

 of the layQr of rich land on which those woods rested. We cannot do better than now to 

 ■call to our assistance the aid of a gentleman who has given, as far as I can find, the best 

 ■explanation of these local phenomena. Dr. P. H. Bryce, M. A., of Toronto. 



But before reading this it would be well to study carefully the few pages following, 

 here, after which the other as connected with these great principles, will be much better 

 ■ comprehended. The article is from the world-renowned pen of Herschel, and is fully in 

 accord with the explanations of writers of a late date : — 



Of Land and Water as Recipients and Communicants of Heat. 



"Of the solar heat which actually reaches the surface of the globe, that which falls on 

 water penetrates it to some moderate depth and is absorbed internally, while that which 

 1 is incident on land is wholly absorbed superficially, or within a very minute thickness. 

 Water, moreover, is eminently a non-conductor of heat, so that once received into its sub- 

 -stance, it is only diffusible by agitation ; and since this, however violent at the surface of 

 ^he ocean, diminishes rapidly with the depth, the ultimate communication of heat down- 

 awards to any considerable depth is a very slow process. By far the greater portion of the 



