FISH-NET PRESEEVATIVES. 



25 



Method of measuring wearing quality. — ^Tlie principle of the method 

 is the obvious one, which consists of drawing or ''sawing" the hnes 

 across some wearing or abrading edge under a constant pull and meas- 

 uring the number of strokes required to wear it out. In practice, 

 however, this proved to be difficult of application. Close-grained 

 wood was tried first, but the results were not at all consistent or even 

 similar for similar samples. It was found that the edge wore sleek 

 at a very inconstant rate. With iron, steel, hard rubber, and even 

 glass the same difficulties were encountered. The most satisfactory- 

 results were obtained by causing the sample to saw against itself at 

 a rather acute angle and under pull of a definite weight. 



The construction and operation of the machine for making this 

 test is shown diagrammatically in Figure 13. To an eccentric, a, are 

 fastened the lines to bo tested, h and h', which are passed over the 

 rollers, h and h', and fastened at c and c'. Other pieces of the same 

 line, d and d', are made fast at e and e', and run through the slack 

 part of h and h', at/ and/'. The samples so attached form angles 

 cfh and efg, etc., of about 13°. Weights of 1 kg. (g and g') are 

 attached to the free ends of the lower piece of line. The eccentric a 

 is revolved by a motor, imparting a reciprocating motion to the sam- 

 ples h and h', which causes them to saw across similar samples, d and 

 d'. The samples thus wear out and the weights drop to the floor. 

 The number of strokes necessary to wear each sample down to a 

 breaking strength of 1 kg. is taken as a measure of the wearing quality. 

 The machine was made so as to run 10 samples at a time, five on each 

 side of the table, and a mechanical revolution counter was used to 

 assist in keeping count. In Figure 9 (p. 21), the machine used is 

 shown with all samples in, ready to start. 



Table 9. — Wearing quality of cotton lines exposed in sea water at Beaufort, N. C. 



A — ^\'Tlite line, untreated control 



F — Coal tar 50 per cent, benzol 50 per cent 



G— Pine tar 50 per cent, benzol 50 per cent 



H — Pine tar and coal tar 25 per cent each, benzol 50 per cent.. 



I— Quercitron and potassium bichromate 



J— Petroleum product No. 1 



L — Dutch method 



M — Copper oleate 7i per cent in gasoline 



N— Copper oleate 12^ per cent in gasoline, oil 5 per cent. 



cresol 1-1000 



O — Copper oleate 12^ per cent in gasoline 



P — Copper oleate \2\ per cent in gasoline, 2 per cent oil 



Q— Copper paint No. 1 plus 50 per cent creosote oil 



R — Copper p£unt N o. 2 



S — G ilsonite 



X— Petroleum product N o. 2 



(^) 

 {^) 

 (^) 



(^) 





 6.1 



22.8 

 5.1 

 41.5 

 11.6 

 14.0 

 (}) 

 (2) 



• Avorage of 100 tests; every other figure in this table is the average of 50 tests. 

 1 Lino was disintegrated and gone. 



Results of wearing tests. — This method of making the mechanical 

 wearing tests on the various samples exposed and tested, though 

 good enough for use and having already given some valuable data, 



