328 



The unusual size and varied forms assumed by the hail- 

 stones that fell during the great storm of May 12 is a sub- 

 ject of considerable interest. The conditions that produced 

 these abnormal effects must have been in some ways excep- 

 tional, but they are difficult to define. It seems moderately 

 clear that the smooth spherical form, described above as 

 No. 1, were the original forms, as they were the first to fall, 

 and they formed the nucleus of more complex forms, as seen 

 in the lenticular, the flask-shaped, and some, at least, of 

 the spinous. 



It is difficult to explain the existence of spines on many 

 of the hailstones. Some of the. spines were cylindrical and 

 blunt, while others were tapering and sharp. Can they have 

 been drops of rain, attached to the hailstone, that became 

 elongated by lagging behind during the hailstone's rapid 

 passage through the air, and ultimately frozen ? These spines 

 often occurred in polar arrangement — that is, at apposed 

 extremities — in pairs of two or four. This appeared especi- 

 ally to be the case with hailstones of elongated form, the 

 protuberances being joined on to either end. 



The lenticular forms, by a similar explanation, might be 

 regarded as the result of a spinning movement of the spherical 

 body which formed the nucleus. The latter, if coated with 

 liquid while spinning on its axis, would exert a centrifugal 

 force on the liquid which might by this means become spread 

 out at the periphery. 



The agglutinated forms had a more or less irregular sur- 

 face which appeared to arise from the union of two or 

 several ice fragments. How was such a union effected ? A 

 mere striking together by collisions would probably result in 

 rebound. Is it possible that hailstones, diversely electrified, 

 may be mutually attracted and coalesce as a consequence of 

 such attraction 'I The regelation that took place was appar- 

 ently complete ; for while an external pattern of a composite 

 structure was clearly marked, there were no internal planes 

 of division — what individual outlines that may have origin- 

 ally existed were lost in the perfect blending into one body 

 of clear ice. 



Except for the milky-like surface of the spherical forms 

 the whole of the hailstones observed were of clear ice, indi- 

 cating that their origin was not that of frozen vapour, but 

 frozen rain. 



General Remarks on the Storm. 



While the hailstorm extended over a somewhat wide 

 area, including the city of Adelaide, the abnormal features 

 were limited to a belt of country, about a quarter of a mile 



