DISCUSSION. by 



would destroy all useless trees, I would suggest that especial 

 attention should be given to the cultivation of thick shady 

 deciduous trees in their place, such as the chestnut, walnut, plane, 

 and sycamore trees on the plains and moderately elevated table 

 lands of the interior, whilst the most valuable species of Californian 

 pines and cedar should be cultivated on the coast range, in order 

 to induce as much as possible that alternation of currents 

 favorable to rainfall. 



Mr. H. C. Russell (Government Astronomer) : — I should like 

 to occupy the time of the Meeting for a few moments, to give 

 expression to some of my own views upon this subject. It is one, 

 as some of the members know, I have paid some attention to and 

 have taken a great interest in, and it is not long since I endeavoured 

 in the public prints to show that the result of investigations carried 

 on in France, England, and America, in what seems to me the 

 most conclusive way of testing the effect of forests on rainfall has 

 been that no such effect can be discovered. Meteorological 

 observations have been carried on in France for about 200 years, 

 and no decrease in the rainfall can be discovered whatever, 

 although the population of France has increased, and necessarily 

 the amount of forests destroyed has been very great during that 

 period. The same has taken place in England and in America. 

 Now to my mind that is the strongest evidence of all. A great 

 deal has been made of experiments carried on with the intention 

 of showing that the temperature of the forest is very much lower 

 than the surrounding area, and that the amount of rainfall 

 deposited on the forest is much greater than that deposited on the 

 plain country near it. But these experiments have continued 

 only for a short time, and the evidence of different observers is 

 so contradictory that it must be taken for what it is worth. It 

 is a difficult thing to ascertain what is the amount of rainfall on 

 a forest as compared with plain country near it. Then again 

 we have statements published that forests are warmer than cleared 

 country at night and cooler by day, and it has been asserted that 

 because forests are cooler therefore more rain is deposited on them. 

 I think those who say this must have overlooked the fact that 

 if the forest is cooler, it is very little cooler, and is a very small 

 body compared with the great extent of atmosphere above it ; and 

 everyone knows that if two masses of air of different temperature 

 are brought together they soon take the mean temperature v of 

 the two, but the forest being but little cooler than the atmosphere 

 and insignificant in extent relatively, it can have scarcely any 

 effect iu lowering the temperature of rain clouds. Again, Nature 

 has provided us in New South Wales with a great stretch of 

 plain country and alongside of it a great extent of forest. From 

 a careful examination of the rain records on both, extending over 

 several years, I cannot detect any difference in the proportion of 



