120 
THE TELEGRAPH . 
their entrance into offices and into tunnels, and at the points of 
connection with subterranean or sub-aqueous lines. It also 
takes the place of the bell insulator in lines of irregular direc¬ 
tion, at sharp angles. These cases occur only on high roads. 
The wire is then kept in this insulator by fastening to it 
Fig. 57. 
the two ends of a fine wire that is wound round the mushroom 
support. 
Iron fittings of a particular form are used to support the 
mushroom insulator according to the different cases we have 
enumerated above. When it is fixed against rock or stone, 
flat galvanized iron supports of the form shown in fig. 56 are 
used ; when it is attached to a flat wooden surface, then tri¬ 
angular supports (fig. 58) are employed. 
