Review of Recent Geological Literature. 179 
On the Buildi)ig and Ornatnentat Stones of Wisconsitt . By Er- 
nest Robertson Buckley, Ph. D. Wisconsin Geological and Natural 
History Survey, Bulletin No. IV. Economic Series No. 2. 
Economic geology is the science of raw materials, and in any such 
state report as this we may recognize three parts, appealing to three 
classes of readers. First, there is the record of scientific fact interest- 
ing to fellow workers in the same field of sciences. Second, there 
may be more or less of a synopsis of what is already known on the 
subject, that the local public may be enabled to appreciate the meaning 
and importance of the scientific facts. And, thirdly, there is a large 
amount of data as to the commercial value of the raw materials which 
appeals to the business man. In this last regard the report- is merely 
an advertisement of the resources of the state. 
The report before us is an important one in all three respects. 
Many of the illustrations particidarly, while far from devoid of scien- 
tific value, seem to find their chief function in adding to the attrac- 
tiveness of the volume as an advertisement. To the readers of this 
magazine, however, it will be most important to point out where in 
this bulky volume, the first class of facts are to be found. 
Part I, "On the Demand, Uses and Properties of Building and 
Ornamental Stones;" and Part II, Chapter I, "A Brief Geological 
History of Wisconsin," are a short summary of the general informa- 
tion needful to appreciate the volume. The description of the methods 
of the laboratory tests, pp. 54 to 74, is, however, an essential part of 
the scientific data. Special attention is given to the question of 
porosity, and especial pains were taken to ensure complete drying. 
To determine the porosity, instead of — 5- — (where a is the weight 
dry in air, b the weight saturated with moisture in air, c the weight 
a 
saturated with moisture in water, the formula la-b) a-c 
a-4-(a-b) — ?_ 
a-c 
is suggested, which gives the percentage of pore space to the volume 
of the rock. It may be noted that — - — is the specific gravity of the 
rock, and has an independent interest. Otherwise it would be vastly 
simpler to put the formula in the form in-d-f- ^'J^ ) 
There is little of novelty in the geological history, which follows 
the lines of Van Hise's and Chamberlin's work, though it is interest- 
ing to note that he finds no occasion to use the term Algonkian, but 
reverts to the Upper and Lower Huronian and Keweenawan. The re- 
mark that "late study of the northern crystalline area has shown that 
much that has been included in the Archean is really Huronian," 
must be read remembering that Archean is not used in the usual and 
original sense, but in its narrower meaning, as applied to a pre-Cam- 
brian, non-clastic formation; in other words, the original crust of the 
earth. 
