33 



Rocky Mountain regions of the West. A case in point occurred during the 

 past summer in the latter part of July over an area of some six or eight 

 square miles along the divide between the basins of Indian Kentucky and 

 Indian creeks and their tributaries, in eastern Jefferson and western 

 Switzerland counties of this State. The rainfall in this case was un- 

 precedented for the region. On one border of the given area a government 

 rain gauge, kept by J. R. Shaw, Jr., was filled to the brim, the measure- 

 ment amounting to three and one-half inches, and then ran over for an 

 unknown period. Afterward the gauge was emptied and received one and 

 one-half inches niore, making at the least Ave inches, and probably m»ich 

 more, in the period of two hours during which the rain fell, Other and 

 more reliable measurements in locations more nearly the center of the 

 storm area were made and a precipitation of at least ten inches in the 

 two-hour period were recorded. 



The conditions producing this exceptional and very destructive rain- 

 storm were as follows : The region to the west and southwest of the 

 storm-swept region is oue of the roughest topographically in southern In- 

 diana. The whole area for ten or twelve miles in this direction forms 

 the basin of Indian Kentucky Creek and tributaries, and the hills rise 

 in many instances 400 to 450 feet above the valleys, and the slopes are 

 very steep. From the whole basin the forests have been almost entirely 

 removed. On the day referred to the temperature was unusually high, 

 some thermometers within the area registering 102 degrees in the shade. 

 There was no movement of the air until early in the afternoon, when a 

 gentle southwest wind arose, and this caused the highly-heated air of the 

 whole region to move northeastward. The valley of Brushy-fork Creek, 

 one of the principal tributaries of Indian Kentucky Creek, became the 

 center of the air movement. About three in the afternoon a cloud began 

 to form above the divide and around the head of the valley of Brushy-fork 

 Creek. The highly-heated air ascended very rapidly on reaching the divide, 

 and the consequent rapid cooling of the air by expansion caused an equally 

 rapid condensation of the moisture of the air. The cloud increased in 

 volume with very great swiftness, and the rain fell in torrents, first over 

 a very limited area and then over a wider region. The center of the storm, 

 however, instead of moving, as is usually the case, remained almost sta- 

 tionary for a period of two hours. During this time the winds from al- 

 most the entire surrounding region moved slowly towards the now en- 

 larged area of precipitation. There were few if any clouds outside of 



