Meteorites and What they Teach us. — Ilenaoldt. 83 
<;nt from those which constitute the crust. It ha8 been estab- 
lished that the average density of the earth is a little over 5^ ; 
in other words the earth weighs 5^ times as much as a globe 
of the same size comi)Osed of water, but that the specific grav- 
ity of the known crust, viz., the average weight of the rocks, 
minerals, etc., with which we are acquainted is less than 2^. 
We are thus driven to the conclusion that the interior of the 
globe is composed of substances having more than twice the 
density of those which we find at the surface. 
Now it seems to the writer that in the meteorites which 
have from time to time fallen upon the earth's surface we 
have been provided with a most important collection of 
objects on which to study the character of its interior. Being 
the fragments of other planets they confirm in a remarkable 
manner those general conclusions which we have been enabled to 
draw from undisputed facts respecting the interior of the 
globe. The density of by far the greatest number of them 
wonderfully coincides with that of the greater portion of the 
globe. It has often been pointed out that the interior of the 
earth is in all probability a vast metallic mass consisting 
mainly of iron, and among the meteorites we have a great 
preponderance of iron-masses, while the different classes of 
meteoric, with exception of the chondrites (which beyond 
doubt have resulted from the accumulation of cosmic parti- 
cles) represent a variety of lesser depths, those which are of 
an essentially stony character being delivered from portions 
of the crust. 
It has been the writer's endeavor in the above to give a brief 
outline of what has been accomplished ^|i recent years by 
those devoted to the study of meteorites. Much of what he 
has stated will be notliing new to those who may be acquainted 
with the existing literature on meteorites and who have kept 
pace with the progress of recent inquiry. But it would gratify 
him if his efforts have awakened more than a passing interest 
in others, if he should have succeeded in showing that the 
study of meteorites has an importance far beyond that which 
they have hitherto attributed to it ; that it is of importance 
alike to the physicist, astronomer and philosopher; that with- 
out it no rational conception of the constitution of this uni- 
verse is possible and that even now no progressive geologist, 
mineralogist, chemist or teacher of natural history — in short 
