STRETCHERS. 
123 
It is usual to number the wires in the manner shown in 
fig. 65, so that they may be known throughout the whole 
route. 
Stretchers , or Strainers .—Double stretchers of the form 
adopted in France, and single stretchers on the Belgian system, 
Fig. 62. 
have been generally used up to the present time. The simple 
stretcher is represented in fig. 66. It is formed of a cast-iron 
drum on the axis of which is a ratchet-wheel. The drum is 
divided by an opening for half its length. A support, formed 
of a strong slip of iron so bent as to allow sufficient space 
