HOW TO DRESS A WET FLY. 89 



the thread must always, during the winding, be 

 strained at the same angle to the direction in which 

 the pencil points. For suppose the pencil to be 

 covered exactly with a rectangular strip of paper, 

 and suppose the thread to leave a mark on the 

 paper ; then, when a spiral has been wound and 

 unwound, suppose the paper to be removed and 

 flattened out. It will appear as illustrated by the 

 shaded portion of the figure (Fig. 50). A marks 

 extremity of the spiral and B the other. 



Now, from the dotted portion of the figure it is 

 easily seen that the length of any spiral reaching 

 from A to B must be equal to the length of some 

 line reaching from A to B', B' being perfectly 

 determinate from the position of B and the 

 number of turns in the spiral. But the shortest 

 of all lines reaching from A to B' is the straight 

 line AB'. Therefore the shortest spiral reaching 

 from A to B is that wound in accordance with the 

 above-mentioned conditions. 



If, now, the ends of this shortest spiral be bound 

 fast to the pencil, it is clear that, unless the 

 thread forming the spiral stretches, it is quite 

 impossible for any part of it to slip. 



We see, then, that to dress a palmer properly 

 it is necessary, both to wind the hackle as has 

 been directed, and to fasten it with the tying silk 

 as soon as it has been wound as far as the shoulder. 

 The wrong method is, after having wound the 

 hackle in open turns up the body, to proceed at 

 once to wind it in a few close turns at the 

 shoulder, without previously making it fast. I 

 trust that I have made this point very clear, for 

 it involves an important principle which is often 

 disregarded. 



When there is any considerable degree of taper 

 in the body, the considerations by which we 

 determine the shortest spiral must undergo some 

 modification. 



