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

THE HINDOSTAN INSULATOR. 557
The cap is of wrought iron, galvanized, eight and a half
inches high, ten and a half inches in circumference above,
twelve and a half inches in circumference below, its lower
edge or rim everted to thirteen and a half inches, closed above,
and perforated to permit the passage of a screw bolt four inches
long and one half inch in diameter. Two strong metal studs,
three fourths of an inch in diameter, and one inch long are
riveted on the cap, one at each side of the screw, for the purpose of preventing lateral motion of the bracket to be afterward
applied.
The cap being inverted, the cement is thus applied. Three
parts, by weight of fine, clean and perfectly dry sand, with
one part by weight of the best pine rosin, are melted in an iron
pot and well incorporated by stirring. The consistence should
be that of thick mud. Enough of this cement to occupy half
an inch of the cap should be poured in and allowed to cool,
which takes about five minutes.
The post is now inverted, and its small end placed on the
hardened cement, so that a clear space of half an inch remains
between the wood and the cap all round. Melted cement is
now poured in so as to fill this space up to the brim. As
the cement cools, it contracts slightly, so as to become concave.
The post must be kept perfectly steady while the cement is
cooling and setting, which occupies about five minutes. It is
now ready to receive the bracket.
The quantity of cement used for each cap is one pound fourteen ounces.
Fig. 65. Fig. 66.
The bracket (fig. 66) is of oak, eleven inches long, four
broad and three deep, perforated in the centre for the passage
of the cap screw, also perforated at one and a half inches from
the end for the passage of the binding screws for the attachment of the iron rods, and having on its lower surface two
cavities, one inch deep, three fourths inch wide, to r ceive the
studs of the cap. On the upper surface a circular hollow is
sunk at each end, one half inch deep and: one and one half
inch in diameter, to receive the necks of the porcelain insulators,
subsequently described.