18 



U. S. BUEEAU OF FISHEEIES. 



heavy growth of ascidians or sea squirts broke the lines and carried 

 them away. The Dutch method followed the tars closely, being 

 not quite so good at first, but better at the finish. The lines treated 

 with copper oleate, M, N, O, and P, showed at the beginning the 



MONTHS EXPOSED 



Fig. 5. — Tensile strength of cotton lines exposed in sea water at Beaufort, N. C. 



usual weakening due to lubrication, but upon exposure lost strength 

 less rapidly than those preserved by either the Dutch method or j 

 tar; in fact, were second only to those treated with the copper paint 

 at the end of six months. 



