12 Opening Address. 



are yet required, however, before any explanation could be 

 accepted as satisfactory. On this subject Strzelecki remarks tV.at 

 " no datum is as yet offered by which we could legitimately indulge 

 in a theory concerning the origin of this remarkable meteorological 

 phenomenon." This excellent observer attributes to the hot 

 wind deleterious effects on the human constitution, partakuig, he 

 says, " of the character of those produced in Egypt by the sirocco 

 or simoom ; a feverish heat and determination of blood to the 

 head, and in those subject to disorders of the lungs a restrained 

 action in breathing, at times bordering on suffocation; 

 relaxation of the muscles and vessels, inflammatory attacks, affec- 

 tions of the glottis, and opthalmia." And in the Hydrographic 

 Notices recently issued by the Admiralty, the hot winds are 

 said to "produce a disagreeable, dry, oppressive, enervating 

 atmosphere, which is frequently injurious to health." I scarcely 

 think that general experience in Sydney would bear out these 

 opinions. Many people feel the north-east sea breeze much more 

 relaxing and depressing than the hot winds, which indeed to some 

 are more exhilarating than relaxing. 



On the subject of the winds of this country, I have been 

 informed that the Eev. AV. B. Clarke published some letters in 

 the Herald about thirty years ago. I regret that this informa- 

 tion came to me so late that I have had no time to look up these 

 letters, nor have I had time to consult Mr. Clarke himself, and 

 the state of his health prevents his being present with us to- 

 night. It is also to me a matter of regret that in the valuable 

 paper on the Climate of Australia, published by Mr. Jevons in 

 Waugh's Australian Almanac twelve or thirteen years ago, the 

 chapter that he had written on the winds of Australia was 

 omitted for want of space. 



There can be little doubt that all winds are caused by differ- 

 ences of atmospheric pressure, these differences being due chiefly 

 to unequal heating of the air, and to unequal distribution and 

 precipitation of water vapour ; and it may be laid down as a 

 general rule that the wind blows from a region of higher pressure 

 to a region of lower. But Professor Buys Ballot of Utrecht has 

 shown that the course is not direct from the one point to the 

 other, but that (in the northern hemisphere) the wind blows to- 



