126 
THE TELEGRAPH 
The most generally used stretcher is the collar stretcher 
(figs. 68 and 69) ; the drum is carried by an iron plate 
attached by a key to a collar that grasps the mushroom 
insulator (fig. 55). 
Two stretchers, of shapes that differ only so far as may be 
required to bring the axes of the drums into the same horizon- 
Fig. 68. 
Fig. 69. 
tal plane, are fixed on the right and left of the support. By 
this stretcher a wire of 0*2 inch diameter can easily be tightened. 
It requires rather more time to fix them than the double stretcher, 
but its insulating support offers greater firmness and a better 
insulation than the tension support as hitherto used. This 
stretcher is especially advantageous in curves, because it allows 
the acting strain to be applied in the direction of the resistance. 
