Geography of the Avr. 49 
REPORT—GEOGRAPHY OF THE AIR. 
‘By Gen. A. W. GREELY. 
It is with a feeling of increased responsibility, shared doubtless 
by the Presidents of other sections, that the Vice-President of 
the Geography of the Air brings before you his modest annual 
contribution in one branch of geographical science. 
We live in an age so imbued with earnest thought, and so 
characterized by patient investigation, that an eager gleaner in 
scientific fields finds at the very outset his mind filled with the 
garnered grain of golden facts. The more cautious searcher 
often follows with uncertain mind, and doubtless in his back- 
ward glances sees many fairer and heavier sheaves than those he 
bears with full arms, from the fruitful harvest. If, then, you do 
not find here dwelt on such geographical phases as you judge 
most important, attribute the fact I pray you, not to neglect, but 
to lack of observation, or to the exercise of an undiscriminating 
judgment. 
First let us turn to the higher class of investigations, wherein 
that handmaid of science, a true and noble imagination, comes to 
supplement exact knowledge, to round out and give full form 
and perfect outline, either shaping a number of disjointed and 
apparently heterogeneous facts into a harmonious series, or evolv- 
ing from a mass of confusing and seemingly inexplicable phe- 
nomena a theory or law consistent therewith. 
In this domain Professor Ferrel’s book on Winds is probably 
the most important theoretical meteorological discussion of the 
past year. It owes its value to the fact that it puts into compar- 
atively simple and popular form the processes and results of his 
intricate mathematical investigations of the motions of the air, 
published by him years since, and later elaborated during his 
service with the Signal Office. 
In connection with the subject of winds, Professor William M. 
Davis has formulated an excellent classification, depending first, 
on the ultimate source of the energy causing the motion ; second, 
on temperature contrasts which produce and maintain winds; 
VOL. II. 4 
