The bottom being reached, the
unwinding suddenly ceases, and there is nothing further to do but read
the indication given by the differential counter, this giving the depth.
[Illustration: FIG. 5.--APPARATUS FOR MEASURING THE LENGTH OF THE WIRE
PAID OUT.]
Near the winding pulley, there is a small auxiliary engine, M, which
is then geared with the axle of the said pulley, and which raises the
sounding apparatus that has been freed from its weight by a method that
will be described further along.
We have endeavored in Fig. 4 to show the aspect of the bridge at the
moment when a sounding was about being made. From this engraving (made
from a photograph) our readers may obtain a clear idea of the Thibaudier
sounding apparatus, and understand how the wheel over which the wire
runs is set in motion by the Brothergood engine.--_La Nature_.
* * * * *
CABLE GRAPNEL.
Some improvements have recently been made by Mr. Alexander Glegg and the
inventor in the well-known Jamieson grapnel used for raising submerged
submarine cables.
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