1868.] Oa a Scientific Exploration of Central Australia. 347 



their periodic time, and is expressed hy the equation a = ^—. This, then, 



may be called the terminal velocity of a wave of a given period. It follows 

 that if a wave is raised through the disturbance produced by a solid body, 

 that wave will at first travel with a speed depending on the virtual depth of 

 the original disturbance ; but as it advances to a greater and greater dis- 

 tance from the disturbing body, the velocity of advance will gradually ap- 

 proximate to the terminal velocity corresponding to the periodic time, and 

 the virtual depth will continually adjust itself to the changing velocity, and 

 approximate gradually to the equivalent pendulum corresponding to the 

 periodic time. Such is the cause of the forward curvature cf the ridges of 

 the obhquely diverging waves which follow a ship*. 



May 14, 1868. 



Lieut.-General SABINE, President, in the Chair. 



The Right Hon. the Earl of Rosse was admitted into the Society. 



The following communications were read : — 



I. Scientific Exploration of Central Australia.'"' By Dr. G. 

 Neumayeh. Communicated by the President. Received 

 April 20, 1868. 



If we look on a map of the Australian continent published ten years 

 ago, we are struck by the immense expanse of land then unexplored ; we 

 perceive at a glance that the south-eastern sea-board only of this great 

 continent had then been examined with any degree of accuracy, and that 

 very little was known to us respecting the character of its shores on the 

 west and north-west. In two quarters only had the zeal and daring of the 

 explorer succeeded in forcing a path towards the central portions of this 

 vast territory, Sturt having penetrated as far as 24^ South and 138° East, 

 and Gregory as far as 21° South and 128° East. The nature of the coun- 

 try traversed by these two eminent explorers was such as to countenance 

 the supposition, that the interior of Australia was little better than one vast 

 desert, offering almost insurmountable obstacles to exploration. The idea, 

 originally advanced by Oxley, that the greater part of the interior was 

 occupied by vast inland lakes, was then abandoned ; and the theory just 

 mentioned took its place. In such a state of utter uncertainty as to the 

 nature of the interior of a vast continent, it is but natural that various 

 theories should be started ; and no doubt they will, in the end, help to keep 

 up the spirit for rigorous examination and exploration, yet care must be 

 taken that they do not, by the unfavourable nature of their suppositions, 

 tend to discourage enterprise. From such a danger we had a narrov/ escape 



^- Tliis is explained in greater detail in a paper read to the Institution of Naval Archi- 

 tects on the 4th of April 1868. 



