IX. 
INTERNAL STRUCTURE AND PROGRES- 
SION OF GLACIERS. 
It is not my intention, in these articles, to 
discuss a general theory of the glaciers upon 
physical and mechanical principles. My special 
studies, always limited to Natural History, have 
but indifferently fitted me for such a task, and 
quite recently the subject has been admirably 
treated from this point of view by Dr. Tyndall, 
in his charming volume entitled “ Glaciers of 
the Alps.” I have worked upon the glaciers 
as an amateur, devoting my summer vacations, 
with friends desirous of sharing my leisure, to 
excursions in the Alps, for the sake of relaxation 
from the closer application of my professional 
studies, and have considered them especially in 
their connection with geological phenomena, with 
a view of obtaining, by means of a thorough 
acquaintance with glaciers as they exist now, 
some insight into the glacial phenomena of past 
times, the distribution of drift, the transportation 
of boulders, etc. It was, however, impossible to 
