50 National Geographic Magazine. 
and third, on their periodicity and the time of the first appear- 
ance of the motion. 
Professor Russell, appropriately it seems to me, remarks 
regarding the landslide winds, that avalanche would be a better 
term than landslide as applied to winds associated with fallen 
masses of earth or snow. 
With the enormous amounts of accumulated tabulated matter, 
and numerous studies bearing on isolated meteorological phe- 
nomena, it is a specially important consideration that some 
students pay constant attention to the investigations of the laws 
of storms. From such researches definite advances in theo- 
retical meteorology may be made and fixed laws determined, 
which may be of practical utility with reference to the better 
forecasting of the weather. In the United States Signal Office, 
Professor Abbe has brought together the results of his studies 
and investigations for the past thirty years, under the title, 
‘‘Preparatory studies for Deductive Methods in Storm and 
Weather Predictions.” This report will appear as an appendix 
to the annual report of the Chief Signal Officer of the army. 
Professor Abbe finds that the source and maintaining power of 
storms depend on the absorption by clouds of solar heat, and in 
the liberation of heat in the cloud during the subsequent precipi- 
tation, which, as he endeavors to show, principally influences the 
movement of the storm-centre. 
In this method one takes a chart showing current meteoro- 
logical conditions, and the permanent orographic features of the 
continent; lines of equal density are also drawn for planes at 
several elevations above sea-level. On these latter, and on the 
lines of the orographic resistance, are based intermediate lines of 
flow, which show where conditions are favorable to cooling and 
condensation. The amount of condensation and its character, 
whether rain or snow, are estimated by the help of the graphic 
diagram. Numbers are thus furnished that can be entered on 
the chart and show at once the character of the new centre of 
buoyancy, or the directions and velocity of progress of the cen- 
tre of the indraft and the consequent low barometer. 
It is hoped that this work of Professor Abbe’s may be, as he 
anticipates, of great practical as well as theoretical value. Steps 
are being taken to test the theoretical scheme by practical and 
exhaustive applications to current work. 
