78 
MCADIE. 
Convenient symbols for representing these were also de¬ 
vised by Howard. The system is unsatisfactory, however, 
in this: that, being based purely upon appearance, no account 
is taken of the origin and manner of formation of the 
cloud. Clouds of very dissimilar origin may have a similar 
appearance. Modern meteorology demands more than a 
record of the appearance of the cloud. It seeks the mean¬ 
ing of each formation and regards the cloud as an exponent 
of the physical processes operating in the air and resulting 
in cloudy condensation. The cloud is primarily valuable not 
on account of its beauty, but because it makes manifest 
motion in the atmosphere, which is not otherwise discernible. 
It outlines to some degree the storm mechanism at different 
levels in the atmosphere. Making due allowance for the 
fact that the cloud does not always give the true motion of 
the current in which it moves, as witness the Table cloud 
at Table mountain, it is still, when rightly interpreted, a 
most significant index of air motion. There is no sound 
reason why the forecaster should not derive as much in¬ 
formation concerning the movements of the air from a 
cloud map as from a pressure or temperature map. A happy 
illustration of the practical use to which a cloud map can 
be put may be found in the storm of August 26-7-8-9, 
1893, more familiarly known as the Sea Islands storm, in 
which 1,100 lives were lost. (Wall map shown illustrating 
cloud movement over the southeastern section of the 
country.) South of Savannah, the telegraph lines being 
down, reports were missing. It was of the utmost importance 
at a time like this to locate the storm center as accurately 
as possible in order to determine its future probable course. 
No pressure readings in southern Florida or Georgia were 
available; yet, even with this rough system of cloud observa¬ 
tion and report, it is obvious that the upper clouds at Lynch¬ 
burg, Knoxville, Chattanooga, and Norfolk locate the “ low ” 
on the Georgia coast, and the chart makes plain that the 
upper clouds at Knoxville were probably moving from the 
