478 DISCUSSION: FORESTS, RESERVOIRS, AND STREAM FLOW 
Mr. Chitten- our forestry friends in a serious tangle, is the fact that the duration 
den, of floods in the second period is in nearly all cases longer than in the 
first. If there is any truth at all in the forestry theory, the removal 
of the forests ought to heighten and shorten the floods; but these 
tables indicate that it lengthens them! In fact, Mr. Pinchot states 
that certain rivers in the South, as a result of deforestation, “disclose 
a marked increase of floods and flood duration”; though, immediately 
after, in the same paragraph, he returns to the conventional theory 
that deforestation leads to “sudden, violent floods of short duration.” 
Discrepancies and contradictions like the foregoing would, as 
already stated, lead a prudent investigator to pause and inquire. He 
could not help seeing that there must be some other explanation. 
Might it not be in the distribution of the rainfall? and might not 
his very method of toning down and smoothing out the records mask 
the particular fact that it was necessary for him to know? Such 
indeed is precisely what has happened. Although the labor of search- 
ing out these individual floods and the attendant rainfall was so great 
that the writer had no time to undertake it, he has fortunately seen a 
most careful recent study covering a portion of the streams embraced 
in Mr. Leighton’s tables and worked out on truly rational lines. This 
consists of three tables (Tables 19, 20, and 21) showing rainfall and 
freshets by months for periods of twenty years for the Ohio at Pitts- 
burg, the Allegheny at Freeport, and the Monongahela at Lock No. 4. 
These tables were prepared in the United ‘States Engineer Office at 
Pittsburg, and, at the request of the writer, their use in this connection 
is permitted. They constitute the most comprehensive study of this 
guestion, on so extensive a scale, that has come to the writer’s notice 
Particular attention is invited to them, for they afford a complete 
explanation of the many discrepancies above pointed out in the study 
by annual means. The following extract is from the notes accompany- 
ing these tables: 
“These monthly comparisons are obviously more significant than 
annual ones, and in general they explain the apparent discrepancies 
shown by the latter. On the other hand the monthly records also exhibit 
some discrepancies that can be readily explained by a more detailed 
examination of such months. In each case they cover a period of 
twenty years and are summarized for the first and second ten-years. 
They all give similar results, showing a greater number of freshets 
for the second period even with a less rainfall. These accordant 
results are somewhat disturbed, however, when we observe the annual 
totals. Here we notice but little consistency in the relation between 
rainfall and number of freshets. On the other hand, this lack of con- 
sistency usually finds a ready explanation in the distribution of the 
rainfall among the different months, and moreover the greater fre- 
quency of freshets in the second period is at once seen to result from 
the very marked increase in rainfall for this period during the month 
of March, which is one of the greatest flood-producing months. Great 
