Ixxx. Proceedings. 



may be predicted from the declination of the moon's orbit : 

 that is, the greatest declination brings the largest amount of 

 rain ; that these periods recur, but not regularly, every six 

 years, and that the periods between are dry. And something 

 of that kind appears to mark the weather. According to 

 the three-years principle, taking the odd years, those 

 divisible by 3, would be the centres of dry periods, 

 whilst those not divisible by 3 would be the centres of wet 

 periods. For instance, 1881 being divisible by 3, would 

 on this principle represent the centre of a dry period. 

 Although this is but rule of thumb, yet there is certainl}' some 

 coincidence between the principle and what we have ex- 

 perienced in the past. The year 1880, up to a certain period, 

 was a dry year, and of the present year the same may be said. 

 People have a peculiar notion about these wet and dry years. 

 For instance, I have asked a great many persons as to the 

 state of the springs aiter this wet month, and all said they 

 must be rising fast. Nothing of the sort, the springs have 

 been falling from the beginning and are still falling. The 

 cause is the amount of evaporation. In 1879 the evaporation 

 from the water surface was only 10 inches ; and the difference 

 between the amount of rainfall and that evaporated would tend 

 to saturate the ground. And all through 1879 a large amount 

 percolated to a depth of 3 feet ; but not a single drop has 

 passed through this year ; the ground is as dry as possible. 

 While we have had a rainfall up to the end of last month of 

 14 inches, the evaporaticn this year has been nearly 20 inches, 

 that is, in excess by 40 per cent, of the amount of rainfall. 

 So that in this sense it is a dry year, and confirms the above 

 rule. Thus the future character of a wet or dry season might 

 be guessed from the amount of water stored in the ground. 

 That will give a much clearer insight into the character of 

 the year than any other sort of observation ; hence the 

 importance of these percolation experiments. During the 

 period of active growth in 1879, nearly all the manure put into 

 the ground was washed out by the rains, except in the latter 

 part ; and the remarkable fact is, that the latter part of 1879 

 was extremely dry. The diminution of the rain towards 

 the end of the year, when the earth becomes sensitive 

 to absorb it, and the period of great dryness that followed, 

 in fact landed us in August last with the low state 

 of the springs ; but in August the ground received before 

 the rainfall a certain amount of moisture, which was 

 due to the increased humidity of the atmosphere. Long 

 before this period, a replenishment of the ground had taken 

 place. Now that could not have een due entirely to the 



