MARYLAND GEOLOGICAL SURVEY 19

included which may appear superfluous to the specialist in geology or
insufficient to a student of allied subjects. Among those who have
aided Dr. Mathews in the preparation of this list are Messrs. Uhler,
Bibbins, Spencer and Bagg; while Darton's " Catalogue and Index of
Contributions to North American Geology, 1732-1891, " Watson's
" Bibliography of Virginia, " and many lists of works on special sub-
jects have been used in checking the references collected.

The cartographic catalogue, somewhat unusual in this connection,
contains most of the original maps and many early or. corrected maps
which show the gradual recognition and determination of the limits
and topographic features of the area of the state. An attempt has
been made to give, as far as possible, the size, character and scale of
the maps, while those maps giving geological data are indicated. The
places where these maps have been found, or the authority on which
their titles are based, are indicated by "Peabody, " "Williams, " etc.
Much help in compilation and correction has been gained from Wil-
liams' " Maps of the Geology included within the State of Maryland, "
Phillips' " Cartography of Virginia, " " Winsor's Narrative and Crit-
ical History, vol. iii, " and Marcou's " Catalogue of Geological Maps
relative to North and South America. "

The First Report upon Magnetic Work in Maryland, which com-
prises Part V of the volume, is made by Dr. L. A. Bauer, who has
been conducting this division of the work of the survey. Dr.
Bauer was for several years connected with the United States Coast
and Geodetic Survey in Washington, and is. now the editor of the
Journal of Terrestrial Magnetism. The present report gives the results
of the determination at a number of points of the so-called magnetic
elements, viz., the magnetic declination, the magnetic inclination or
dip, and the horizontal component of the earth's magnetic force.
These three elements completely determine the direction and inten-
sity of the magnetic force prevailing at the points where observation
is made. The results of the work are of great importance to the
county surveyors and others who are engaged in determining the
boundaries of lands, and for other public matters where" the accurate
determination of the magnetic points is required. This important,