Forecasting the Weather and Storms 



trees would offer but little more resist- 

 ance to the tornado than would so many 

 blades of grass, and the drawing off of 

 the electricity of the clouds by the pro- 

 jecting points of the trees would have 

 no effect, as it never has been shown 

 that electricity has anything to do in 

 originating tornadoes ; it is rather a 

 result than a cause. The planting of 

 trees is a useful occupation, even if they 

 have no effect on tornadoes ; but what 

 shall one say of the municipality that 

 hires a cannoneer to guard the southwest 

 approaches to its city and to destroy 

 with shot all tornado clouds, as a small 

 western city once did. Still its action 

 was no more ridiculous than is that of 

 certain provinces in Europe that an- 

 nually expend large sums of private and 

 public money in the shooting of hail 

 clouds, or of otherwise intelligent peo- 

 ple who aid and abet the most ignorant 

 of charlatans in their pretensions of 

 making rain or of forecasting the 

 weather months in advance. 



There is a wide variation in the num- 

 ber of tornadoes that occur during the 

 years. Chart No. XIX shows the loca- 

 tion and the direction of movement of 

 all the tornadoes of a year of small 

 number, and chart XX shows the re- 

 sult of a year of great frequency. 



FLOODS 



With our many thousands of miles of 

 navigable rivers flowing through one of 

 the most extensive and fruitful regions 

 of the world, daily forecasts of the height 

 of water in the various sections of each 

 river are of enormous benefit to naviga- 

 tion, and the warnings issued when the 

 precipitation is so heavy as to indicate 

 the gathering, during the near future, 

 of flood volumes in the main streams 

 are often worth many millions to navi- 

 gators and to those having movable 

 property on low grounds contiguous to 

 the streams. 



The feasibility of making accurate 

 forecasts as to the height of water sev- 



eral days in advance at any station of 

 the system is no longer questioned, and 

 at stations on the lower reaches of rivers 

 one to three weeks' forecasts are feasi- 

 ble. The forecaster at each river center 

 considers the rainfall, the temperature, 

 the melting of snow, if there be any, the 

 area and slope of the watershed, and the 

 permeability of the soil. From a study 

 of floods in former years he knows the 

 time necessary for the flow of the water 

 from the tributaries to the main stream 

 and the time required for the passage 

 of the flood crests from one city to an- 

 other. The forecasts are, of course, 

 empirically made, but still they are 

 sufficiently accurate to possess great 

 value to the people of the river districts. 



Some idea of the vast destruction of 

 property due to floods may be gathered 

 from the statement that the floods of 

 1 88 1 and 1882 caused a loss of not less 

 than $15,000,000 to the property inter- 

 ests of the Ohio and Mississippi Valleys. 

 There was also a loss of 138 lives. In 

 1884 the region of the Ohio alone suf- 

 fered a loss of over $[0,000,000 in prop- 

 erty. In 1897 the l° ss along the sev- 

 eral great rivers was more than the sum 

 of the two large figures just written, 

 and in 1903 the destruction of property 

 might fairly be estimated at $40,000,000 

 in value. 



From data that now covers many 

 years at a large number of stations the 

 following general relations have been 

 deduced : The time it takes high water 

 to pass from Pittsburg to Wheeling is 

 one day ; from Pittsburg to Parkers- 

 burg, two davs ; from Parkersburg to 

 Cincinnati, three days ; from Cincinnati 

 to Cairo, six days ; from Cairo to Vick- 

 burg, seven days, and from Vicksburg 

 to New Orleans, four days. The time, 

 therefore, from Pittsburg to the Gulf is 

 23 days. Similar general relations con- 

 cerning the movements of other rivers 

 have been determined. Since the time 

 is so great — the movement of high water 

 being a little slower than the current — 



