The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

AUSTRIAN AND PRUSSIAN INSULATORS. 553
seen by the sectional fig. 58. The Fig. 58.
wire is twisted around the neck s y
of the cap. When more than one
wire is used on the route, the insulators are fixed to brackets or
iron arms. 1Ii
On the line from Frankfort to
Castel, opposite Mayence, I noticed, in 1854, the wire was insulated with a covering of india-rubber, fixed in a notch at each
pole. Over the notch was fastened a piece of tin to serve as
a roof.
THE AUSTRIAN AND PRUSSIAN IN'SULATORS.
Fig. 59 represents an insulator used on some of the Austrian
lines. The post T is tapered to a point c, about two inches in
diameter at top, and the tapered part above c is about six inches
long. A porcelain cap or inverted cup is fitted to the tapered
end. On the top of the cap at e there is a small groove or hole
a, in which the conducting wire b b is fastened.
Fig. 59. Fig. 60.
The Prussian telegraph lines are remarkable for their perfection as to construction, and particularly in regard to the efficiency of their insulation. Fig. 60 represents the mode of
insulating heretofore employed on many of the lines in Prussia and Hanover. The cap is made of porcelain, four and one
half inches high, three and one half inches wide below, and
one half an inch thick. These caps are fitted to iron arms as