H 4 
THE TELEGRAPH 
ropes carry the weight, w, by means of hooks. The cast-iron 
base is placed on the spot where the post is to be erected, and 
on the top of it a rope collar is fitted to deaden the impacts. 
A rod passes through the upper part of the tripod and is fixed 
temporarily in the base, and this serves as the guide for the 
weight, w, through which it passes. When w has been drawn 
up to the top it is allowed to fall upon the rope collar, and the 
operation is repeated until the top of the cast-iron base is 
level with the ground. The guide rod is then removed, and 
the iron post fixed in its place. At first the post was fixed 
with cement as in Siemens’ system, but now it is secured by 
iron wedges of different sizes. These posts are very firm, and 
never swerve in the ground. It will easily be understood that 
the earth is compressed and rendered firm by the driving in of 
the wedge-shaped base like a stake. 
A form of iron post patented by Lee & Rogers of Man¬ 
chester, and known as the riband iron post , is made of angle 
irons of various heights, connected by intersecting bands of 
wrought-iron, which are riveted together where they cross 
each other and the angle irons. The whole is firmly fixed in 
a cast-iron foot ending in a tripod base. 
This post has not been much used in telegraphy. It is 
elegant, but it is not very firm, and it has little resistance for 
lateral strains. It can rarely be used, and then only in cases 
where its lightness and elegance recommend it to favour. 
Insulating supports. —The insulators used for supporting 
the conducting wires are usually formed of a porcelain bell 
into which an iron hook is fixed by plaster. The bell is 
sometimes fixed to the post by a galvanized iron stirrup 
and two screws, and sometimes by means of a support. One 
of these arrangements for a small insulator is shown in 
fig. 51. The larger insulator represented in fig. 52 differs 
from the former in size, in the shape of the stirrup, and 
in having a double inside bell of ebonite (hardened or 
vulcanized india-rubber) by which the hook is covered. A 
beech-wood support is interposed between the neck of the 
insulator and the post. This is the Belgian form of insulator. 
In fixing the small insulator to the post it is necessary to 
compress the stirrup by means of a small screw-press so that 
it may tightly embrace the bell. In this way the latter is 
