B. Test of Rein Collection lsthod If the collection of precipitation is to be used as a method of following the denosition of fallout sr, it would be highly desirable to increase the collection period to about one menth, During a lon neriod of collection, the collector woul’ be alternately dry end wet. Under these circumstances, jt mav be considered that a sigrirficant amornt of fallout vould be blo-m out of the collector during dry veriods between rains or accumulated in excess when the coilector contained water, As a test of these possibilities, a number of collections made at Chicago during March, April and May 1955 included, in addition to the stardard oven tub, a second tub covered with a tlastic sheet with a small cenier hole and a third tub -rith the -yeter Isvel nsintained at an irch or :nore by periodically adving water, Results for the "covered" tud ard "wet" tub collecticns have veen resorted in Chicago Eulletin No, 11 and in this report, In the case of the "wet" tub, the volume reported is thet cbtained from the ccilector area and denth of precipitation resorted bv the “leather Bureau for the University of Chicago station, The total Sr70 activity collected by each of these methcds can be directle compared since the collection areas are eoual, 1. Period 1000, March 16, 1955 to 9915, March 21, 1955 CL 59-P CL éo-P 2. Oven tub Covered tub 29.0 + 2.0 dpm total 31.8 + 2. 2 " u Period 1530, March 21, 1955 to 1000, April h, 1955 CL 62 & 456 Open tub CL &77 3. The data are as follows: Wet! tub N¥0O hS.1 + 4.0 dpm total 35.2 ¥ 2 ec n "! Period 0950, April h, 1955 to 1,00, April Us, 1955 CL 551-P CL 552-P Open tub Covered tub 29.0 + 1.9 dpm total 34.3 + 2.4 " " ¢¥