104 TALKS AFIELD. 



The Compass-Plant. 



Adventurers upon the prairies of Illinois 

 and upon the plains west of the Mississippi 

 early recognized a leaf compass in the great 

 lower leaves of the rosin-weed. These leaves 

 stand nearly vertical, with their faces pre- 

 sented to the east and the west, and their 

 edges to the north and the south. So marked 

 is this polarity that travelers can often di- 

 rect their journeyings by the positions of the 

 leaves. The first record which was ever 

 made of the polarity of the compass-plant 

 was that given by Major Benjamin Alvord 

 of the United States Army to a scientific 

 journal in 1842. A second communication 

 appeared from him the next year. So in- 

 credulous were scientists in regard to the 

 polarity of the plant, however, that Major 

 Alvord in 1849 again made record concern- 

 ing it, this time before a body of scientists 

 in Cambridge, and with the support of state- 

 ments by other army officers. 



There have been many conjectures as to 

 the cause of the peculiar attitude of the 

 leaves of the rosin-weed. Major Alvord at 

 first supposed that the leaves contained suf- 

 ficient iron to render them magnetic, but a 



