/ 
50 Caricography. 
Four of the observations of Prof. Locke exhibit errors greater 
than 10’. They are 
Madison +27’ . Prairie du Chien — 20’ - 
Columbus — 23 Louisville +12, 
The observation at Charlottesville exhibits an error of +26’; 
and that at Baltimore by Prof. Courtenay —44’.. This is by far 
the greatest error of all the observations, if we except that made 
at Pittsburgh in 1819. The observation was made in the mid- 
dle of the city, and it may be presumed that the needle was sub- 
jected to strong local attraction. In my former paper, I noticed 
the Pittsburgh observation as being specially anomalous. My 
own observations show that there was here an error from some 
source of about five degrees. 
It is believed that the accompanying chart will be found to rep- 
resent the lines of equal dip for the northern part of the United 
States with a good degree of accuracy. For the southern states 
they could only be drawn conjecturally, as I know of no obser- 
vations of dip made in this country south of the parallel of thirty 
eight degrees. 
Arr. VI.—Caricography ; by Prof. C. Dewey. 
(Appendix, continued from Vol. xxx, p. 64.) | 
Sivce the last number of the Caricography, only a few addi- 
tions have been made to the Carices of North America. An elab- 
orate monograph of the Cyperaceze of our country by Professor 
Torrey, was published in the Annals of the Lyceum of New 
York in 1836, which contained a list of our known Carices, with 
the additions which his extensive correspondence and facilities 
had made to them, and such corrections as were judged necessary 
from a more full acquaintance with this extensive genus. Ina 
future paper, a new arrangement of the species may be give, 
which shall embrace all the later discovered species and some 
corrections. In this paper it is proposed to continue the history 
of the species which have been found in the United States, that 
the few later discoveries may be generally known. After all the 
ardor with which Carices have been sought, and the multitude 
found, itis wonderful that any have remained to be detected. 
Those species described by the early examiners of our country, 
have nearly all been ascertained, offering strong presumption that 
all of them will yet be found and identified. 
