226 H- J- Dunn ■ 



Professor Grant, 1 Dr. Summers; 2 Profeisor^Skeats, 3 and others 

 have suggested that the forms of australites arc due to rotary action, 

 and these small examples certainly appear to favour this view. 



Darwin and the licv. W. B. Clarke were the first to suggest that 

 the forms of australites were due to rotary movement. 



It is for the phvsicist now to demonstrate by actual experiment 

 whether molten ^lass by rotation would form such bodies, and also- 

 whether the flow structure so well shown in sections of australites. 

 could be produced by rotary action alone. 



Experiments might result in determining how long such small 

 bodies would remain plastic in the atmosphere, and in this way the- 

 height "above the surface at which they commenced their career 

 could be determined, also the speed of the revolutions necessary to- 

 produce these forms from molten trlass before it lost its original 

 viscosity ami became rigid. 



Should such experiments prove that australites owe their* form' to- 

 rotary movement, and that they are not the blebs of bubbles, then 

 the problem of their distribution remains still to be solved, : and in 

 this connection it may be mentioned that in the auriferous alluvial 

 gold working at Stony Creek, Grampians, 'Victoria, an irregular 

 fragment of obsidian 2 inches long and J inch broad, finely pitted on 

 the surface and showing How structure, was found in the wash-dirt 

 associated with examples of australites. It is somewhat water worn 

 and appeal's to have lain long in the gravel. A chip has quite 

 recently been detached which shows its vitreous nature. The speci- 

 men belongs to Mr. Ferguson, an officer of the Geological Survey, 

 and ii is in the Geological Survey Museums. Melbourne. The same 

 means that transported this fragment from its volcanic source could 

 have also transported the australites found with it. 



In the groove between the core and the rim of some australites 

 there is a white substance that under the lens appears to be silica. 

 Dr. Du Toit. of the South African Geological Survey, drew my 

 attention to Hue lines that radiate from the centre of the underside 

 of ^om<- of the button-shaped australites. This feature occurs on 

 several examples. 



List of Localities of Australites shewn on Plate. 



Pig. I- Mt. William Col, IHeld. Grampians, Victoria. 



do. do. do. do. 



-- ••'.. do. do. do'. do. 



I Proc. Roj Soc. Victoria, vol. \\i., part ii.. ]>. 413. 



Australian Association for the Advancement of science, vol. xiv.*, Melbourne, 1918. 

 I' Roy. Soc. Victoria, vol. xxvii., part ii., p. :{<>."!. 



