KEYIEWS. 
417 
of the theory of the conservation of energy— for such his hypothesis really is — 
will be known to many a generation in the future, when the mere lawyer 
is completely forgotten. We think, therefore, that the writer of the book 
before ns may very well be pardoned for the following sentence : — “ Every- 
one is but a poor judge where he is himself interested, and I therefore write 
with diffidence ; but it would be affecting an indifference which I do not 
feel if I did not state that I do believe myself to have been the first who 
introduced this subject as a generalized system of philosophy, and continued 
to enforce it in my lectures and writings for many years, during which it 
met with the opposition usual and proper to new ideas.” 
Of this book it would be difficult to speak too highly, for it is a master- 
piece of reasoning extending over the whole range of physical science, and 
tending in every way to prove the master’s idea, viz., that force is inde- 
structible. It would be out of place, in a short notice such as this, to 
introduce lengthy quotations, and yet without them we could not attempt 
to show the extremely happy manner in which the author explains what 
were at one time regarded as the complexities of his case. Of the style of 
the book, too, we cannot say too much. It is indeed a masterly essay. 
Whether the author has done well to add his several papers bearing on the 
subject and printed elsewhere we shall not say, but it appears to us that 
the book would have had more interest to the general student had they been 
absent. However, many of them are intensely interesting, and as a whole 
the volume is one that, like Mr. Darwin’s “ Origin of Species,” should hold 
a place in every scientific man’s library. 
GEOLOGICAL SURVEY OF MISSOURI.* 
T HIS report, accompanied by nearly two hundred illustrations, and a large- 
folio atlas of sections and typographical maps, is divided into two 
parts, the first of which is chiefly devoted to the distribution, description, 
and mode of occurrence of the iron ores, by Dr. Adolf Schmidt, and the 
second part to the area and topographical features of the coal-fields by Mr. 
G. C. Broadhead, who also furnishes an account of the geology of seven 
counties, together with a geological report of the county adjacent to the 
Pacific railroad from Sedalia to Kansas city ; and in the same part the 
general and economic geology of Lincoln county is described by Mr. W. B. 
Potter. The first chapter, somewhat bearing on the subject of the iron ores, 
is by Mr. Ralph Pumpelly (the director of the survey), treats of the geology 
of Pilot Knob and its vicinity, from which it appears that porphyry forms the 
entire substructure of the region, which, however, had been eroded into hill& 
and valleys before the deposition of the overlying lower Silurian limestone. 
The porphyries are stratified, belong to the Archeean (Azoic) formation, and 
are considered to be the near equivalents of the great iron-bearing rocks of Lake- 
Superior, New Jersey, and Sweden. These rocks have undergone immense 
* “ Geological Survey of Missouri. Preliminary Report on the Iron Ores- 
and Coal-fields from the Field-work of 1872.” New York : 1873. 
YOL. XIII. — NO. LIII. E E 
