55i Transactions. — Miscellaneous. 



whereas when the range is over 1,500ft. in height the rainfall 

 will be heaviest on the western or windward side. In tliis 

 colony the 1,500ft. limit will have to be raised to perhaps 

 3,000ft. or more, on account of the lower latitude. Eemember- 

 ing this, it is not difficult to explain a good many anomalously 

 heavy rainfalls in the colony. In the Kakaia Gorge, e.g., rain 

 comes often heavily fi'om the north-west, admitted presumably 

 over the lower passes or cols in the vicinity. So in the 

 neighbourhood of Mount Cook and elsewhere there is seen 

 something similar, as described by Mr. McKay.* Even at 

 the head of Lake Wakatipu the heaviest rainfall is from the 

 north-west, so that some portion of the rainfall which is gene- 

 rally considered to fall almost entirely on the westei'n flanks 

 of the Southern Alps must pass over the lower elevations on 

 the western side and reach the central portion of the range, 

 and even the eastern flanks, in diminished quantity. 



Loomis gives the following causes of excessive rain- 

 fall :— 



(1.) Mountain- sides deflecting prevalent ocean- winds up- 

 •ward, so that much of their vapour is condensed by the cold 

 of elevation. 



(2.) The high temperature and great humidity of those 

 winds. 



(3.) Proximity of district to sea. 



(4.) Influence of storm-tracks. 



And as causes of deficient rainfall he mentions — 



(1.) Absence of adequate cause to produce strong upward 

 movements of air. 



(2.) Chains of mountains between the place in question 

 and the sea, which obstruct the prevalent winds and rob them 

 of theh moisture. 



In the light of these general principles, it is not difficult to 

 understand most of the local peculiarities as well as general 

 features of the rainfall of Xew Zealand. Its mountains run 

 along its greatest length — i.e., from north to south— minor 

 ranges deviating only a few points from this du'ection. The 

 weather coming from the west, the eastern plains are com- 

 paratively dry, and the west coast is very rainy. 



Dr. Hann confesses " that, on the whole, he has not suc- 

 ceeded in coming to a clear understanding of the winds of these 

 Islands and their causes." He attributes this partly to all the 

 stations being on the coast, and so subject to the disturbances 

 of land- and sea-breezes. But Sir James Hector points out 

 that the influence of mountains and gorges has been still 

 greater in afi"ecting the observations, and thinks the only reli- 



* Trans. N.Z. Inst., vol. vii. 



