39 
caused by the breaking-up of the stone into fragments, sometimes 
into one or two thousand pieces, at others into two or three 
only. 
Meteorites may be roughly divided into three classes :—1., 
those wholly metallic (Siderites) ; 11, those composed of stone 
and metal in about equal proportions (Siderolites) ; 111, those in 
which stony matter largely preponderates (Aerolites). Mr. Pank- 
hurst pointed to a model of a typical specimen of the first class 
seen to fall in Arabia in 1865. Ninety-two per cent. of it was pure 
iron, the remainder nickel. No other metals but these two are 
found in the metallic state in meteorites. Common as iron is, 
it is one of the rarest things on earth in its pure state. It is not 
the least remarkable of the many remarkable things connected 
with these bodies that the purest iron men have hitherto obtained 
has come from the sky. These alloys of nickel and iron often 
show a beautiful crystallization. About 20 years ago a notable 
discovery was made in Greenland. In a vast outpouring of 
basalt huge masses of an alloy of iron and nickel were discovered. 
It is analogous in composition to that of some meteorites, and 
among other substances was accompanied by graphite and ~ 
olivine. 
The second class (Siderolites) is represented by specimens of 
the stones which fell at Estherville in Iowa in May, 1879. The 
largest mass weighs 437 lbs. and is now in the British Museum ; 
one of the smallest, in Mr. Pankhurst’s own possession, only 15 
grains. Nearly 1,000 lbs. weight of matter came to the earth at this 
fall. Of the third class (Aerolites) there is a characteristic speci- 
men from the Brighton Museum collection, which fell at Pultusk 
in Poland in 1868. Some two thousand are said to have fallen ; 
great numbers, however, being very small. By the side of the 
Pultusk stone is a section of a very similar one which fell at Mocs 
in Transylvania in 1882. It isa typical specimen of an Aerolite. 
The grey rocky matter is mainly silica, magnesia, and iron, and, 
curiously enough, it is analogous in composition to those lavas 
which are regarded as having been erupted from the deepest por- 
tions of the earth’s crust. Scrutiny through a microscope throws 
some light on the strange secrets of its genesis. It is largely 
built up of small spherical granules (chondoi) which seem to have 
condensed in molten drops from some fiery cloud. _ Mineralogic- 
ally, the rocky portion of meteorites mainly consists of bronzite, 
enstatite, and olivine. In some stones a species of felspar is 
found ; sulphur also, though generally in combination with metals, 
and in some very extraordinary stones carbon is met with. The 
elements which principally enter into their composition are iron, 
nickel, oxygen, magnesium, aluminium, carbon, sulphur, 
chromium, and phosphorus. No new element has been found, 
but several compounds peculiar to the laboratory of space. 
