IOWA ACADEMY OF SCIENCES 
225 
These tables ajid charts show clearly: 1. That the area of greatest 
precipitation is not the same for different stations. They suggest that 
the cyclonic distribution of precipitation bears a definite relation to cli- 
mate, and varies with this. 
2. That if the area of greatest precipitation is to the southeast of 
the center of cyclones in the Upper Mississippi Valley (as taken for 
granted hitherto in general works on American meteorology?) there 
must be a very marked diurnal shifting of this area concerning which 
nothing is at yet known; for to make up for the deficiency of precipita- 
tion in this part ctf the composite cyclone of the morning hour theio 
would have to be a corresponding excess during some other part of the 
day. 
3. That, in either case, the variations in the location of this area of 
greatest precipitation, be they local or diurnal, are quite probably of 
sufficient magnitude to appreciably affect the accuracy of weather fore- 
casts. 
Explanation of Figures. 
Plate XVII. 
Fig. 1. This figure shows the location of each of the twenty-five 
tracts as averaged in each cyclonic area. The numbers are those given 
under the columns “number of tracts” in the preceding tables. 
Pig. 2. Distribution of precipitation and wind directions in a com- 
posite cyclone,- based on the 8 A. M. observations taken at Davenport 
during the years 1893-1897. 
Pig. 3. Distribution of precipitation and wind directions in a com- 
posite cyclone, based upon the 8 A. M. observations taken at Amarillo, 
Dodge City, Wichita and Oklahoma during the years 1894-1898. 
Fig. 4. Distribution of precipitation and wind directions in a com- 
posite cyclone, based upon the 8 A, M. observations taken at Helena, 
Miles City, Leander and Boise City in 1899. 
Fig. 5. Distribution of precipitation and wind direction in a com- 
posite cyclone, based on the 8 A. M. observations taken at all the stations 
in the Upper Missouri Valley during 1899. 
Fig. 6. Distribution of precipitation and wind direction in a com- 
posite cyclone, based on the 8 A. M. observations taken at Detroit and 
Buffalo during the years 1900-1903. 
Note: In the figures numbered 2, 3, 4, 5 and 6, the shading repre- 
sents different percentages of precipitation as follows: 
Solid black, 
Crossed parallel lines, 
Parallel lines. 
Interrupted parallel lines, 
No shading, less than 
40 peri cent, and above. 
:t0-39 per cent, 
20-29 per cent, 
10-19 per cent, 
10 per cent. 
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