A CONTRIBUTION TO THE STUDY OF AUSTRALITES. 3 3 
For one of these curious glass bodies that fall to the earth, 
there must be millions of falling stars, and yet these small bodies 
are never found, and they would be just as easily found as Austral- 
ites or Billitonites. Observations show that a man watching 
the sky under favourable circumstances would if he kept his 
eyes fixed on one spot of the heavens sec from five to sixty-nine 
falling stars per hour or an average of over eleven throughout 
the year. Altogether it is believed from several computations 
that from 15 to 25 millions of small meteorites reach the earth 
as falling stars every day. This is counting only visible meteorites 
and they are not all glowing and visible so there can be no 
questioning their much greater profusion than Australites. 
Siderites require some 2,912° F. of heat to fuse them ; these 
glass bombs would require only 2,383° F. (which is the same as 
1,524° C.) ; yet I have here as you can see a perfectly shaped 
lens form Australite weighing just 4.9 grains which has a sharp 
straight edge all round and shows no sign of distortion as it 
must if it had reached the globe even very slightly plastic (Plate 
XVI. Fig. 5.) 
The temperature necessary to produce a fluid glassy lava 
denotes a very hot volcano for the production of these bodies. 
From what I read, the temperature of Vesuvius which produces 
a plastic crystalline lava is very little more than half that stated 
by Professor Kerr Grant to be necessary to fuse Australites. 
Volcanoes producing glass are rare in this world ; those 
producing stony lavas are common. It is curious that the only 
lava meteorites reaching us should be glassy though plutonic 
aerolites often occur. 
I cannot understand why Professor Kerr Grant should take 
the trouble to consider rotation forms as accounting for the 
Australite shapes as a glass meteorite could never so fuse from 
the friction of the atmosphere as to become a mass of molten 
alass ; if it did it would be instantly dispersed into microscopic 
dust by the opposing air. If it did become as suddenly heated 
as would be the case from air friction at the rate of progression 
of a meteorite it would tend rather to decrepitate or chip than 
fuse and the time occupied bv its passage of the whole atmosphere 
would be too short to permit any but the smallest to be heated 
to such a temperature all through as to fuse it. In any case 
there would be no time for them to take rotation forms and cool 
again before reaching the earth. 
Without any question these bodies have been cold except 
perhaps their very surface at the time they struck the ground 
or they must have been distorted. 
When a siderite such as an ordinary falling star which is 
believed to enter our atmosphere on an average about the size 
