420 



V. S. BUREAU OF FISHERIES 



SUMMARY OP RESULTS OF ASTORIA EXPERIMENTS 



1. The best preservative of tensile strength tested on hemp and 

 cotton was the copper oleate-coal tar mixture. 



2. As preservatives of tensile strength of manila hemp, there is 

 very little difference between coal tar and the copper oleates. 



3. At this place the effectiveness of the several preservatives is the 

 same for hemp as for cotton. 



4. The quercitron and ammoniacal copper sulphate mixture 

 caused an immediate decrease in tensile strength of manila hemp 

 and was of no value as a preservative for this material. 



2 3 4 5 



NUMBER OF MONTHS EXPOSED 



Fig. 6. — Tensile strength of hemp lines at Astoria, Oreg. 



SERIES EXPOSED IN FRESH WATER AT PUT IN BAY, OHIO 



PURPOSE OF THE EXPERIMENT 



For the purpose of obtaining further data upon the variation in 

 rate of deterioration of twine exposed in different years in the same 

 locality a second series of lines was exposed in Lake Erie at Put in 

 Bay, Ohio, from June 25 to December 25, 1923. 



WATER CONDITIONS AT PUT IN BAY 



The average monthly temperatures of the water at Put in Bay 

 during the period of the test are shown in Table 3. 



