IOWA AC.^DEMY OP SCIENCES. 
67 
many trips by rail through the flooded district. The terrible 
strength of the water flow then became apparent and, noting 
the limited drainage area of Dry Branch in particular, I began 
to take more interest in the event, believing at this time that 
the real precipitation must be about five or six inches. I have 
since made a thorough canvass of the county and record for 
those interested in these phenomena only those things which 
are beyond dispute. 
At 10 o’clock on Monday night, August 15th, it began to rain. 
The precipitation was not extraordinarily heavy, and while it 
rained steadily no one noticed that there was anything unusual 
about it. According to good authority, the so-called cloud-burst 
began about 2 o’clock A. M. and ceased shortly after 4. It 
rained more or less for an hour later, however. A liberal esti-' 
mate of time for the heavy rain is three hours. The precipita- 
tion outside of these three hours, from all accounts, could 
hardly have been more than two inches. 
The area of heavy rainfall can be approximately bounded on 
the south by the divide between Spring creek and Flint river. 
The former stream was not out of its banks. Keokuk reports 
a trace only. The county line forms a close boundary on the 
west, Yarmouth being in the edge of the heavy rain, but suf- 
fered only from lightning. Washington reports 1.72; Iowa 
City, .40. The north boundary of very heavy rain is not far 
above the county line, Wapello reporting 5.16. On the east, 
the river was the boundary for excessive rain, although the 
precipitation was heavy as far east as Biggsville, 111. This 
maps out two-thirds of Des Moines county, or approximately 
250 square miles. The Flint river and its tributaries drain 
one-half of this area. Dry Branch, Yellow Springs, Dolbee 
and Swank creeks drain the remainder, save a strip of three 
miles in width, which drains north into Louisa county. Dry 
Branch drains only about eleven square miles, yet its waters 
caused much damage. Yellow Springs creek drains a much 
larger area and carried, perhaps, more water, proportionately 
to its bed, than Dry Branch. 
It is not easy to estimate the rainfall accurately. There 
were no rain gauges in the county at this time". I shall give 
some of the reports as I obtained them. Great care has been 
taken to get accurate and truthful accounts in this phase of the 
investigation. 
