ABBE!. 
source; everywhere kites and balloons, mountain stations 
and cloud observations are being utilized as means of study- 
ing the upper atmosphere, while on the other hand each 
national weather bureau is extending its field of observation 
horizontally, so as to secure a broader weather-map. The 
insight we get by the help of mechanics, the help we can de- 
rive from mathematical physics, the suggestions that we get. 
from cosmical physics, the new ideas that we get from the 
laboratory study of chemistry, electricity, and radiation, the 
broadening of our field of observation by the use of wireless 
telegraphy, all conspire toward the better establishment of 
our science and consequently the perfecting of the daily pre- 
dictions. 
ELE M EN TAR Y M ETEOROLOG Y . 
In every branch of human activity we begin with the 
simplest ideas and easiest actions, and then progress to the 
most complex combinations and most difficult constructions, 
eventually arriving at abstractions of whose essence we know 
nothing, but whose effects are observable and measurable. 
This statement applies to all branches of science, and meteor- 
ology is no exception. We begin with the direct testimony 
of the senses, then we recognize the abstract idea that force 
must pervade nature and must be the foundation of all the 
phenomena that we have apprehended by means of our five 
senses. 
The simplest atmospheric phenomena were first observed, 
and these stimulated the earliest philosophers of classical 
antiquity. Until most recent times meteorology was not 
advanced by the work of professional meteorologists so much 
as by occasional contributions from those whom we ordi- 
narily speak of as astronomers, geographers, physicists, chem- 
ists, but who in earlier times were known as philosophers. 
To the astronomers we owe certain fundamental facts, 
namely, that the earth is a sphere, that it rotates on its axis 
and revolves about the sun and that its axis is inclined to the 
ecliptic. To establish these few simple points required two 
thousand years — from the days of Eratosthenes, born 276 
