Obsidian Bombs iv Australia. 43 



think that they were produced by natural agency, but the shape 

 and superficial appearance suggest a mould in the ground, the 

 sides being formed by slips of bark or wood, which produced 

 the grooves. The plastic material, he supposes, was not poured 

 but pressed into it by a saucer-shaped mould. It is strange, if 

 they have been used by the aborigines as charms or ornaments 

 and so distributed by them, that no authentic record is extant. 

 "We hear of them being in the possession of the natives, but I 

 have not been fortunate enough to find anybody who has actually 

 seen tliem in use. Professor Spencer tells me that he never saw 

 them worn by the natives of Charlotte Waters, where they 

 occur plentifully, and that no notice of them whatever was 

 taken ; and even if they were distributed in this way to some 

 extent, it brings us no nearer to the discovery of the point or 

 points of origin, upon which the proof of a terrestrial origin 

 must necessarily depend. As a matter of fact, nowhere within 

 the colonies has any eruptive point, however far distant, been 

 proved to have produced objects of a similar nature from which 

 the aborigines could have obtained them, and therefore they 

 could only have found them scattered on the surface in the 

 manner in which we know them to occur. 



Twelvetrees and Petterd's hypothesis, that they might have 

 been distributed by winds, although original, cannot be regarded 

 as a satisfactory solution of the problem. That objects of their 

 size and weight could have been carried by winds from their 

 place of origin, which is assumed to be outside Australia, to 

 their ultimate position is incredible. It is true that volcanic 

 ash may be carried many hundreds, and even thousands, of miles 

 from its place of origin, as was instanced in the last eruption of 

 Krakatoa, in 1883 ; and in the western States there occur 

 remnant beds of tine volcanic dust, such as must have originally 

 covered many square miles of territory, but the sources from 

 which they were derived are now wholly ob.scured. In this case, 

 however, we are dealing with a totally different material. 



Professor Bonney calculates that it would take from 4000 to 

 25,000 particles of volcanic dust from Cotopaxi to make up a 

 grain in weight, and it will be well understood that if dust of this 

 fineness reached the upper currents of the atmosphere, it would 

 remain suspended for lengthy periods, and might be then 



