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

538 TELEGRAPH INSULATION.
lation of the line wire from earth currents. At numeral 1,
fig. 21, the cone is concave. When the water collects upon
Fig. 20. Fig. 21. Fig. 22.
the upper part of the insulator it does not follow the glass to
the numeral 1, but falls from the centre projection. The
moisture under the drip forms globules, and breaks from the
cone at or above 1, as seen falling from the flange of the cone,
fig. 25. The point of drip, therefore, is not at the lower end,
Fig. 23. Fig. 24.
but above at the centre projection as just described. Fig. 26
represents the drip of a house. The falling drop breaks.the
rain and keeps dry the projection seen under the eave of the
house. In the same manner the dripping from the above
described glass insulates the lower cone from the rain. Of
Fig. 25. Fig. 26.,D ___