Proceedings. Ixxxi.. 



immediate rainfall in September, if the ground had been as dry- 

 as it is now, because we know that in September 1879 the 

 wells began to rise long before the rain began to fall. So that 

 there is no doubt that when the earth begins to cool down, as 

 it does every night, and we have very heavy dews, a large 

 amount of moisture is absorbed, and the earth becomes sensi- 

 tive to pass rain through. When reading a paper here some 

 time ago on the subject of rainfall I mentioned that there had 

 been an enormous increase of rain in this district, especially 

 during the last 40 years. It was something like 23 inches 

 during the first decade, 1840-50, 24 inches in the decade end- 

 ing in i860, 25 inches in that ending in 1870, and 28 inches in 

 the decade ending lasting year. Now, what can be the cause 

 of this enormous increase ? I think it is due to the increased 

 growth of timber in the country and the large planting of trees 

 which has taken place of late years. We have authentic 

 information showing that when trees were cut down in certain 

 islands, the springs disappeared, but that when these places 

 were replanted the springs commenced to flow again. I have 

 had a number of holes bored into some trees in my garden, 

 and I found a remarkable difference between the temperature 

 of these trees and that of the external air. In summer the 

 trees are always colder, and therefore they act as condensers 

 of moisture, just in the same manner as elevation causes an 

 increase of rainfall. In the winter, on the other hand, they 

 give warmth ; and as we see an increase of temperature in 

 winter leads to an increase of rainfall, so the multiplication 

 and increased growth of trees increases the rainfall both in 

 summer and in winter. 



Dr. Carpenter remarked, in reference to the absence of 

 sunshine upon the land generally, and the consequences that 

 have befallen us from that cause, he would wish to see added 

 to Mr. Corden's tabular statistics, if possible, some information 

 as to the amount of carbonic acid that might be present in the 

 atmosphere. He believed that in consequence of the enormous 

 extension of manufactures in this country, and the enormous 

 amount of carbon now daily oxidised all around us, there would 

 be found, if a record had been kept, a sensible increase in the 

 amount of carbonic acid in the atmosphere at present. If the 

 amount was found to have increased from two, 40 years ago, 

 to four parts in 100 now, and five or six sometimes, that 

 influence would make itself felt undoubtedly on the general 

 welfare, or otherwise, of the inhabitants. The ditTerence 

 which that condition of the atmosphere would make in the long 

 run must have some effect, because the air containing a larger 

 amount of that acid than usual, effects would be produced 



