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monk in the year 1650, and in 1674 two Swedish sailors on 
board ship, were struck dead by aerolites. 
These meteoric stones have been divided into three classes : 
aerolites, siderolites, and aero-siderolites. The first class, the 
aerolites, comprise the greatest number of meteoric stones that 
have been seen to fall. They all, wherever they have fallen, 
whether in Europe, Asia, Africa, or America, present a most 
striking resemblance to each other. They are stony masses, 
covered with a very thin black rind, where they have not been 
broken after their fall. Internally, they are of a greyish white, 
and of a somewhat gritty structure, like coarse sandstone. They 
consist of various silicates interspersed with isolated particles 
of nickeliferous native iron, meteoric pyrites, &c. 
Professor Daubree proposes to divide these aerolites into two 
classes — (1) Those which give after fusion a crystalline mass, 
and (2) those which give a vitreous mass. The first corre- 
sponds to those meteorites composed principally of magnesian 
silicates, and the second to those composed principally of 
aluminous silicates ; the latter being extremely rare, Professor 
Daubree having found four specimens only out of 150 different 
stones preserved in the collections examined. It is certain, 
says M. Daubree, that some terrestrial rocks, and at their head 
lherzolite, present a composition identical even in its varia- 
tions with that of the common type of meteorites. This 
lherzolite is a common eruptive rock in the Pyrenees, and is 
considered generally to be a massive variety of pyroxene. 
The structure of aerolites, though chemically identical with 
some of the basaltic or eruptive rocks, is not mechanically the 
same. Mr. Clifton Sorby, in his microscopical researches into 
the composition of meteorites, states that “some isolated 
portions of meteorites have also a structure very similar to 
stony lavas ” ; and again : “ this sometimes gives rise to a 
structure remarkably like that of consolidated volcanic ashes ; 
so much so, indeed, that I have specimens which might at first 
sight be mistaken for sections of meteorites/* 
Tne second class of meteorites — the siderolites — consist of a 
sponge-like body of nickeliferous native iron, whose cavities 
are filled more or less with crystals of siliceous minerals, 
pi incipally olivine. Of those preserved in the British Museum, 
not one has been observed to fall from the sky. The third 
class, called the aero-siderolites, are composed almost entirely of 
masses of native iron, more or less combined with nickel. Out 
of eighty specimens preserved in the British Museum, only five 
have been seen to fall from the heavens. The remainder are 
believed to be meteorites, for the following reasons. Such 
