56 Fly -rods and Fly -tackle. 



discover the real character of the board without first 

 ruining the paint. By employing the same waterproof- 

 ing process two lines may be made, one of the best and 

 the other of very inferior material, which will so closely 

 resemble one another that no purchaser can tell them 

 apart except as the superiority of the one over the other 

 becomes evident by use. While both may be quite 

 strong enough when bought, it is obvious that the bet- 

 ter line has a much wider margin for deterioration be- 

 fore the safety limit is reached, and, consequently, that 

 it will outlast and is really cheaper than the other. 



For example, some cheap enamelled waterproofed lines 

 were obtained and submitted to the chief expert of a 

 large silk-mill for analysis and report. They looked as 

 good as ,the best. When procured I could not break 

 them with my bare hands. But when the waterproof- 

 ing composition was dissolved away and the textile 

 residue crucially examined, they were found to be made 

 up of a thin silk covering braided over a cotton core. 



The basis of all these waterproofing mixtures is what 

 the organic chemistries call a "drying oil" usually 

 linseed-oil. Other things are mixed with the oil ; what, 

 each maker keeps as secret as he can. One might as 

 well ask a man what he said and did when he proposed 

 to his wife and expect a full, true, and explicit answer, 

 as to ask a line maker how he made his waterproofing 

 mixture and expect to learn anything definite from him. 

 The drying of these oils is an oxidation process, and the 

 products of this oxidation are extremely acrid. No 

 common vegetable fibre, perhaps no vegetable fibre, 

 will endure their action without ruinous deterioration. 



The oxidation of linseed-oil is carried on on a large 

 scale in the manufacture of linoleum. Cotton-cloth 



