616 president's address. 



toll from the crops of the agriculturist. As a community we 

 seem strangely slow to learn by experience. The introduction of 

 sheep and cattle, to say nothing of rabbits, has been a profound 

 factor in altering the balance of Nature in Australia, and when 

 in addition useful and harmless creatures alike are persecuted 

 out of existence in a spirit of mere idle brutality, it is little to be 

 wondered at that nature retaliates in no uncertain way. 



OCEANIC PHYSICS. 



Taking advantage of the generous latitude in the choice of a 

 subject for his Annual Address which in the past has been 

 accorded to your President, I desire to ask your attention to-night 

 to one to which I have devoted some study during the last few 

 years — that of Oceanic Physics. 



The study of the features of our ocean as they present them- 

 selves to the physicist is very necessary if we are to clearly 

 understand the problems with which we, as naturalists, are 

 continually faced in the course of our observations on the sea and 

 its living denizens. For a proper comprehension of the more 

 important phenomena pertaining to our ocean we must take a 

 great step backwards and draw an imaginary picture of what 

 were the physical conditions of the cosmos at extremely remote 

 periods in geological time. The exigencies of our subject take us 

 far back down the ages to the ver}'^ genesis of the world, and 

 knowledge placed at our disposal by the researches of modern 

 investigators renders it a comparatively simple matter to picture 

 to ourselves the conditions which must have prevailed when the 

 sea lirst began to come into existence. The nebular hypothesis 

 provides that at one stage in the history of the solar system, of 

 which our world is so small a unit, the matter of which it is 

 composed was in an extremely finely divided or nebulous 

 condition, and occupying a very great volume in infinite space. 

 At this time, what is now our solar system probably formed one 



