Note- Taking and the Use of Maps, Etc. — Foerste. 229 
As to general Humphreys, late chief of engineers, I have received 
from him all sorts of proof of his friendship, asking me to renew my 
connection with the engineer corps, which I did, in accepting first, an 
exploration of a part of southern California in 1875 ; and second in 
helping Capt. A. W. Wheeler in his report on the "Third International 
Geographical Congress, at Venice, Italia," 4to, Washington, 188(3, 
which contains such a complete report upon the national geological 
surveys of the world, due entirely to me, although my name does not 
appear in the title, but only and sparingly in the introductory note. 
Cambridge, Mass., September, iaS9. 
NOTE-TAKING AND THE USE OF MAPS IN GEOLOGICAL 
FIELD WORK. 
By AcG. F. Foerste. 
For geological work covering only a small area and confined 
to the consideration of simple, or at least single problems it is 
often unnecessary to keep any detailed system of notes. As 
the area under investigation increases in size, or the problems 
suggested by the same become more intricate it is no longer 
safe to trust to memory for the facts, and notes carefully pre- 
pared in the field are imparatively demanded. If the notes 
taken for this purpose are not too numerous great individual- 
ity of methods of recording the same may be permitted with- 
out detriment to the work or loss of time. With each man, 
however, there is a limit at which notes arranged indiscrimi- 
nately can no longer be readily found, and some sytem must 
be devised by which notes referring to any part of the country 
under investigation may be readily found or the localities 
described in any series of notes may be readily traced on the 
map. Having frequently noticed the difficulties experienced 
by geological friends in the use of methods of many different 
kinds, I have thought that possibly it might be of some assist- 
ance to geologists in general to describe a system I devised 
some years ago, which as a matter of originality is not of a 
high order, but which for its practicability in actual field work 
has shown fewer defects than any system I have actually used, 
in all cases where the country under investigation has been 
accurately mapped. 
A map or series of maps covering the entire country under 
investigation is secured. On these are traced two series of 
parallel lines at right angles to each other. It has been found 
in practice that a distance on the map corresponding to one 
