278 THE AMERICAN NATURALIST. [VOL XXXIII. 
with a brief summary of each work. L. A. Bauer contributes a 
chapter on magnetic work, with a preliminary isogonic map of the 
state. In addition to the usual study of economic products, the plan 
of the Survey embraces a special investigation of road materials, of 
artesian well prospects, of water power, and of the physiographic 
features of the state. A geological map of the state, published in 
cooperation with the United States Survey, is incorporated in the 
volume, with also many photographic illustrations, a view of the 
topographic model of Maryland, index maps showing the progress 
of work of the United States Survey, and a hypsometric map. 
The second volume is even more attractive than the first, the half- 
tone illustrations being supplemented by numerous photogravures on 
heavy paper, and colored plates showing the intimate structure of 
polished slabs of building stone which are, in the opinion of the 
reviewer, the most perfect reproductions of natural rock surface that 
have ever been made. Especially remarkable is Plate II, a granite 
porphyry from Ellicott City, in which even the cleavage fractures on 
the surface of the feldspar crystals and the semi-transparent appear- 
ance of the fracture edges are portrayed with perfect accuracy both 
as to color and form. After the administrative report of the super- 
intendent, this volume contains a full account of Maryland building 
stones, by Dr. Mathews, with an introductory chapter on the physi- 
cal, chemical, and economic properties of building stones, including 
methods of testing, by George P. Merrill. Dr. Mathews’s work 
appears again in the third part of the report, in an exhaustive histori- 
cal review of the maps and map-makers of Maryland. It is in these 
historical chapters that the first volumes of the Maryland Survey 
especially excel, and in them is shown the advantage of the extensive 
library facilities of Baltimore and Washington. Henry Gannett, of 
the United States Geological Survey, contributes a summary of the 
aims and methods of modern cartography, giving from his wide 
experience a systematic account of the object of the modern topo- 
graphic map, the methods employed to-day in the government office, 
and figures and formule illustrating the use of instruments: This 
chapter by itself is of great value in giving to the public a statement - 
of the latest methods of topographical surveying, with excellent pho- 
tographic illustrations of the several instruments employed. 
The second volume shows the success of the first efforts of the 
State Survey in impressing on the people of the state the value of 
its work, in that the General Assembly of 1898 passed special bills 
appropriating money for the extension of the topographic survey 
