DISCUSSION : FORESTS, RESERVOIRS, AND STREAM FLow 415 
of comparison. Therefore, only the December to May floods will be Mr. Leighton. 
considered. In making this comparison, the ideal condition would be 
to compare the rainfalls and floods during identical conditions of 
climate, but such a refinement is impossible. On the other hand, the 
multiplication of data afforded by the large number of flood-producing 
storms in the December-May period warrants the conclusion that the 
varying climatic conditions in this period are compensated, and the 
final conclusions which are drawn from the result must be worthy of 
confidence. Dividing the period covered by these 313 floods equally, 
two consecutive 12-year periods are afforded, which give a basis of 
comparison. The floods in the later period, resulting from a given 
depth of storm precipitation, are shown clearly to be more severe than 
in the earlier period. The method of presentation further makes it 
possible to compute the increase in flood tendency due to deforestation. 
In the Tennessee basin it is 18.75 per cent. 
If the number of flood days is divided by the number of storms, 
the result will be the number of days per storm. Applying this to each 
of the series in Table 18, the result given in Table 14 is reached. 
TABLE 14.—Days or Fioop per Storm, 1884-1895 anp 1896-1907. 
Storms, in inches precipitated. 
Period. - 
1-1.5 | 1.5-2 | 22.5 | 2.5-8 | 33.5 | 8.5-4 | 4-4.5 | 4.545 
1884—1895 0.7 0.5 2.5 1.8 2.6 5 6 8.1 
1896—1907 0.4 0.9 2.6 2.7 3.2 6 8 6.7 
Percentage of increase. | — 43 80 4 50 22 20 | 33 | —1% 
The algebraic sum of these percentages is 149.00 and the ‘average 
is 18.75, which sums up the effect of deforestation on run-off from 
1884 to 1907, inclusive. 
The author devotes some space to a discussion of the effects of 
forests on rainfall, and concludes that there is little or none. For the 
purposes of the present discussion, the question is in no wise involved. 
The requirements are satisfied with the record of actual precipitation, 
be it decreasing or increasing. Colonel Chittenden, however, over- 
steps the bounds of conservatism when he asserts: i 
“Coincident with our recent high waters, which are attributed so 
largely to deforestation, there has been an increase in precipitation, 
where there should, apparently, have been a decrease.” 
Let the author examine the precipitation records over the basins 
of the Tennessee, Cumberland, Kentucky, Pemigewasset, and Catawba 
Rivers, and he will be*convinced that his generalization, in these 
important instances at least, is quite the reverse of the truth. 
