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POPULAR SCIENCE REVIEW. 
that have been recorded, one only (as far as we can ascertain) 
has been wanting in it. We refer to the black fused crust 
or rind with which the surface of meteoric stones is covered. 
It usually extends not more than a few tenths of an inch into 
the substance of the stone, and is supposed to result from the 
extreme rapidity with which they descend into the oxygen of 
our atmosphere, causing them to undergo a slight and partial 
combustion, which, however, from the short time necessarily 
occupied in their descent, has not sufficient time to penetrate 
beyond the surface. On cutting and polishing the stones, if the 
smooth face is treated with nitric acid, it will in many cases be 
found to exhibit lines and angular markings, commonly known 
by the name of “ widmannsted figures.” These are tracings 
of imperfect crystals, whilst the broad intermediate spaces, 
preserving their polish, point out those portions of the stone 
which contain a larger proportion of nickel than the rest of 
the mass. We may here add that the noise, said at times to 
accompany the fall of aerolites, does not appear to be a con- 
stant characteristic, nor does the cause or exact nature of it 
seem able to be definitely specified. 
In conclusion, we cannot do better than advise those of our 
readers who desire further information on this subject, to take 
the earliest opportunity — if they have not done so already — of 
paying a visit to the magnificent collection of meteoric stones, 
contained in several glass cases at the end of the Mineral 
Gallery at the British Museum. The catalogue for the year 
1856 gave a list of between 70 and 80 specimens ; in 1863 
this number had increased to 216, mainly through the energy 
of the Curator, Mr. Maskelyne ; and since that date there have 
been several further additions. Chief amongst continental 
museums may be mentioned the Imperial collection at Vienna, 
as possessing a series of specimens, remarkable alike for their 
size and importance. 
SUMMARY OF AEROLITIC DESCENTS WHICH HAVE TAKEN 
PLACE IN GREAT BRITAIN AND IRELAND. 
England. 
1623. January 10. 
1628. August 9. 
1642. August 4. 
1680. May 18. 
Ermington, near Plymouth, Devonshire. 
Hatford, in Berkshire. 
Woodbridge, in Suffolk. 
In the neighbourhood of London. 
