ep 
this phenomenon, will be shown in another number of this 
ournal, 
Art. XXVIII.—The “Timber Line ;’ by HENRY GANNETT. 
In Dr. Rothrock’s valuable report on botany, recently pub- 
lished by the ‘Surveys West of the 100th Meridian,” the author 
quotes Dr. Engelmann’s statement that “there is little or no 
increase in altitude in the timber line toward the equator, in 
our western hemisphere, south of the 41st parallel of north 
latitude.” 
This statement is approximately true regarding the Rocky 
Mountains, owing, however, not to any general principle, but 
to what may be termed an accident of topography. Even here 
a decided rise is observable from 41° to 39° of latitude. In the 
feet, has a mean temperature, not of 37°, as the height might 
indicate, but of 49°. 
