Taylor and Wells. — Preservation of Nets and Lines. 41 



^on the sample, if the sample does not stretch, the distance be- 

 tween the jaws remains constant; if any stretch occurs, the jaws 

 move away from each other, and this motion is transmitted to 

 a sheet of cross section paper by which means is recorded the 

 up-and-down movement or ordinates, representing stretch. At 

 the same time the motion of the weight lever is transmitted to 

 move the pen, causing to be recorded the horizontal component 

 of the line, which is the abscissa. Thus the machine not only 



Fiff. 1.- 



MONTHS EXPOSEO 



-Tensile strength of cotton Imes <^xposed to weather conditions 



at Washington, D. C. 

 measures the tensile strength of the sample, but the stretch, and 

 records both, automatically. The measurements of tensile 

 strength were made in a room of constant temperature and con- 

 stant humidity. 



The tables and graphs reproduced herewith give the results 

 of the tensile strength tests so far obtained in the various series. 



EXPERIMENTS ON EFFECT OF WEATHER (aIR CONDITION). 



Fig. 1 represents the results (given in Table II) of the series 

 which were placed on the roof of the Fishery Products Labora- 

 tory in Washington. As regards what happened to the tensile 

 strength of the lines in the long run, the results fall easily into 

 two groups, those preserved with tar, (F, G, H) and Petroleum 

 Product No. 1 (a proprietary preparation) on the one hand ; and 

 white lines, those preserved with copper oleate, Bull's method 

 -and the Dutch method on the other (B, C, D, E, I, L). Water- 



