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. 



Art. VI. — Caricography ; by Prof C. Dewey. 



(Appendix, continued from Vol. xxx, p, 64.) 



Since 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 Cyperaceas 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. In a 

 future paper, a new arrangement of the species may be given, 

 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, it is 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. 



