i8o The American Geologist. March, 1900 
The reviewer is by no means sure that the word is not more useful 
in the sense in which it was used by its sponsor, Dana. 
The next part, from chapter II. pp. 88 to 347, consists of detailed de- 
scriptions of the dififerent quarries, commercial and scientific. Here 
there is a wealth of detailed information. Descriptions of polished and 
rough specimens are conjoined to microscopic examinations, and phy- 
sical tests and frequent analyses. This part of the work is very valu- 
able, giving us some real insight and definite facts as to the correlation 
of texture and physical properties. There are excellent illustrations 
of polished granites, and rhyolytes or porphyries. 
The Potsdam sandstones are quite elaborately treated and impor- 
tant hints given as to improving the reputation of the same. 
In chapter VIII, pp. 358 to 420, are assembled together the results 
of the physical tests which have been previously given in the descrip- 
tion of each quarry, and this is by far the most important chapter of 
the book. 
As to crushing strength the figures run unusually high, and while 
every care seems to have been taken and three dififerent machines were 
used, one would like to' have more comparative tests by the same 
machines and manipulators of specimens taken elsewhere which 
have been tested. At the same time, the few tests of Wisconsin 
stones made elsewhere which are given, harmonize well with the 
series. The high crushing strengths, 47,000 lbs. per sq. in. for the 
Berlin rhyolyte (porphyry), and over 40,000 lbs. per sq. in. for the 
granites, with an average crushing strength of the igneous rocks of 
26,000 to 27,000 lbs. per sq. in., are theoretically highly interesting, 
though as the authors say over 8,oqo lbs. is enough for any ordinary 
structure, and the crushing strength is a much overrated test for 
practice. 
Their tests of the transverse strength are much more important, 
as it is not uncommon to see cracked sills. All but some of the sand- 
stones were passable. 
The modulus of elasticity was also determined and like the crush- 
ing and transverse strength was lowest in sandstones. 
In the specific gravity no great variation was noticed in each kind 
of rock. For instance we have for 
+ •058 
Granite, Sp. Gr 2.655 — 026 
+ •048 
Limestone 2 . S08 — . 068 
-f .029 
Sandstone 2.631 — .107 
The iron coloring the brown sandstones has no perceptible effect 
on the sp. gr. As a rule there is no relation between the specific 
gravity, and the strength or porosity of a rock. All the granites 
weighed within 5 lbs. of 165 lbs. per cubic foot. , 
The porosity or per cent by volume of pores is less than one per 
