CORRUGATED DISK PULLEYS.


This is a pulley recently introduced by Messrs. J. and E. Hall, of
Dartford Eng. With the exception of the boss, which is cast, it is
composed entirely of steel or sheet iron. In place of the usual arms a
continuous web of corrugated sheet metal connects the boss to the rim;
this web is attached to the boss by means of Spence's metal. Inside
the rim, which is flanged inward, a double hoop iron ring is fixed for
strengthening purposes. The advantageous disposition of metal obtained
by means of the corrugated web enables the pulley to be made of a
given strength with less weight of material, and from this cause and
also on account of being accurately balanced these pulleys are well
adapted for high speeds.

[Illustration]

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[KANSAS CITY REVIEW.]




EARLY HISTORY OF THE TELEGRAPH.


Although the electric telegraph is, comparatively speaking, a recent
invention, yet methods of communication at a distance, by means of
signals, have probably existed in all ages and in all nations. There