370 PROCEEDINGS OP SECTION E. 



A noticeable instance of evaporation over a large surface is 

 furnished by Lake Omeo, which in 1882 was a sheet of water two 

 miles long by one mile broad, and with an average depth of pro- 

 bably two feet six inches, or less. The lake became dry in 1884, 

 and this accords with the following approximate results from the 

 evaporator at Omeo, viz., thirty and a-half inches per annum. It 

 must be borne in mind, however, that the evaporation from a sheet of 

 water freely exposed to the accelerating iniiuenceof summer winds, 

 would be greater than that from a situation sheltered by high 

 ranges. 



There are not wanting evidences that spontaneous evaporation 

 is in excess of rainfall over many areas at sub-alpine localities ii 

 the Australian Alps. 



Hailstones, although frequent in the higher regions of the 

 Australian Alps during summer and autumn, are not so at sub- 

 alpine latitudes, although it is somewhat remarkable that the size 

 of the hailstones is frequently mucli larger at elevations of 2,000 

 to 4,000 feet, than at higher levels. I have noted hailstones 

 fully half-an-inch to three-quarters of-an-inch diameter. As a rule, 

 the hailstones come fi'om the westward, and are generally accom- 

 panied by electric discharges, or strong wind. 



The higher points of the Australian Alps are noted for the 

 excessive dew which is deposited every evening during midsummer. 

 Dr. von Lendenfeld remarks, that he never experienced in any 

 part of the world, at any height between 10,000 and 15,000 feet, 

 such dews as occurred every night at his camp on the Kosciusko 

 plateau. I have experienced similar phenonema on all the higher 

 points over 5,000 feet. 



The lowest mean tempei-ature of the dew-point is reached 

 during the month of July, and highest during February, corres- 

 ponding in this respect to the temperature of the air. It may be 

 interesting to note that the humidity of the air varies greatly 

 during the summer months, especially at the higher elevations ; 

 and at the lower levels, as at Omeo, the shifting of the wind 

 from north to south-west and south, sometimes causes an excessive 

 humidity, as shown by the dense fogs which frequently envelope 

 the higher points over 4,000 feet ; during summer a feature con- 

 nected with such hygrometric conditions arewhat is locally termed 

 southern fogs. 



The greatest mean velocity of the wind occurs during spring 

 and summer, and principally with north-westerly currents of air. 

 On the whole, westerly winds may be said to predominate in the 

 Australian Alps, although local influences at lower sub-alpine 

 altitudes, cause deflection and obstruction to aerial currents. A 

 remarkable phenomenon connected with the temperature of wind 

 which has been frequently noticed in tlie sub-alpine valleys of the 

 Australian Alps, is the occasional whifls, during frosty mornings, 

 of warm currents of air, producing an irritation of the throat 



