384 T^he America7i Geologist. June, 1900 
In Part I Dr. Clark gives an account of the organization of high- 
way investigation by the Maryland Survey. In Part II he discusses 
highway construction in relation to topography, climate and geology. 
This section includes a detailed discussion of the lilhological and 
geological characteristics of the different regions of ^Maryland, the 
account being concerned especially with showing the relative adapta- 
bility of the different formations to highway location and construc- 
tion. 
Part III, by St. George L. Lioussat, deals with highway legisla- 
tion from the historical standpoint. He shows the relation of means 
of communication to the economic development of the state, and 
mentions many incidents of interest concerning the highways in co- 
lonial times. 
The remaining sections treat the subject from the economic stand- 
point. Mr. A. N. Johnson, engineer of the board of commissioners of 
Massachusetts, traveled over 2,500 miles of Maryland roads, and the 
report of his investigations is embodied in Parts IV and V. He gives 
statistics of the mileage of different kinds of roads in the different 
counties and discusses the location, grading, drainage, surfacing and 
maintenance of the various kinds of roads. This section is admirably 
illustrated by maps showing the different sorts of roads in their re- 
lation to geological structure. 
Dr. Reid contributes the remaining sections. Part VI deals with 
methods of selecting suitable road materials, and concludes with a 
table showing the results obtained from various tests performed upon 
various rocks in the laboratory of the Highway Division. Part VII 
deals with the administration of roads in Maryland, in other states, 
and in Europe. Part VIII describes the advantages resulting from 
good roads. 
This volume equals its predecessors in typographical workman- 
ship. Its 460 pages are admirably illustrated by thirty-five plates and 
thirty-eight figures. i. H. o. 
The Natural History of cordierite and its associates. J. J. H. 
Teall. (Proceedings of the Geologists' Association vol. xvi, part 2, 
pp. 61-74, 1899.) 
This interesting review of cordierite and its associates, sillimanite, 
corundum, andalusite, spinel, is designed to emphasize some recent pe- 
trological facts that bear on the phylogeny, so to speak, of these mine- 
rals, and especially of cordierite. The author assumes that, as a rule, 
cordierite crystallizes in individual prisms in contact and metamorphic 
rocks and in multiple prisms in volcanic rocks, and with this as a crite- 
rion he assigns some of the cordieritiferous rocks to the igneous category 
and others to the metamorphic. The kersantyte dike near Michaelstein 
is an instance. He infers that it must have been in a completely molten 
state when injected into the clay slate because the contained cordierite 
is in six sided prisms which break up into sectors in polarized light. 
The author epitomizes the recently published experiments of I\Ioro- 
sewicz on the production of these minerals from a molten mass who 
