EEVIEWS. 
79 
For our part we are inclined to join issue with Mr. Hull, on some points — 
two in particular. Tirst, we think he has underated the annual drain upon our 
coal-store : and, consequently, the supply he calculates upon will not last a 
thousand years. Moreover, we think the exhaustion T\"ill be accelerated by a 
much larger increased demand than the three millions of tons he allows. But 
then on the other hand we do not think he has admitted all the available 
store we possess. He has restricted mining-operations within a depth of four 
thousand feet, on account of the increase of temperature — regarded, generally, 
by geologists as equal to one degree of Tahrenheit for every sixty feet — and 
that greater depths present insurmountable difficulties for engineering operations. 
Doubtless, in one sense tliis is a right way to view the question, because as increased 
depth causes proportionably increased expenses, and greater cost of the material 
the more we should be placed at a disadvantage with respect to other nations 
whose coal-fields might be more accessible. When needs must, however, our en- 
gineers will undoubtedly surmount both the difficulties of mining, and find also 
some plan for keeping the mine cool enough for the workmen. We must also 
bear in mind that if the temperature increase with the depth, it does so in an 
ever decreasing ratio ; and that from one degree to fifty feet from the surface, 
we have at greater depths to go seventy-five or eighty feet for an equivalent 
increase. 
Our space, however, will not allow us to discuss these questions at length. 
JVIr. HuU's book opens out a very important subject for consideration, and will, 
we trust, draw a wider attention from the public, and more detailed information 
from the School of Mines. Some important data have already been priuted by 
Mr. Robt. Hunt, in his Mineral Statistics ; and we hope to see these extended, 
and the whole subject grappled with in a manner worthy of a national institution. 
Mr. Hull's book deserves attentive reading; and being inexpensive, that 
result ought to be attained. 
On, tJie Primordial Fauna and the Taconie System. By Joachim Barrande ; 
with additional Notes, by Jules !NL\iicou. Boston, U. S. : ISGO. 
One great value of scientific research is the kinship it makes between peoples 
who would else know little of each other, and without it have no inducement 
to become better acquainted. Commerce is said — and very truly, too — to 
make communion between man and man, though a geographical division of a 
thousand leagues may part them ; but the deep thinking men of any nation, if 
this was the only "free passport," would be sliut out from participation in the 
great and varied benefits accruing from an extended intercourse. For they, 
whom " men of business" usually look upon as " half Avitted," and as men be- 
hind the age — " busying themselves about things unprofitable, and past finding 
out" — have no stake in the Avide-cast net which is fast covering the earth, and 
drawing its riches into certain Vortices of trade, to the impoverishment of 
the many and the enrichment of the few. So that unless rock unto rock 
answered as truly as American cotton does to English gold, or African ivory 
to Birmingham guns, the value of the highest scientific researches a man could 
engage in would be lost in its best and noblest sense, from being locked up 
within the brain that imagined it, or exported wildly, without hopes of an im- 
ported return corresponding to it in value. Science whicli conduces to com- 
merce, being made subservient to the lower purposes of trade, will always be 
cosmopolitan in its extension, and be well thought of everywhere; but it is of 
theoretical geology we are now writing, and this, because it cannot be made 
to agree with any standard of human weight or measui'emcnt, commerce will 
have imught to say to. But here do not let us be misunderstood. We have 
