th a very sensitive governor,
capable of being so adjusted that any required speed may be given to
the carriage and model. The resistance which the model encounters in
its passage through the water is communicated to a spiral spring, and
the extension this spring undergoes is a measure of the model's
resistance. The amount of the extension is recorded on a revolving
cylinder to a much enlarged scale through the medium of levers or bell
cranks supported by steel knife edges resting on rocking pieces. On
the same cylinder are registered "time" and "distance" diagrams, by
means of which a correct measure of the speed is obtained. The time
diagram is recorded by means of a clock attached to an electric
circuit, making contact every half second, and actuating a pen which
forms an indent in what would otherwise be a straight line on the
paper. The distance pen, by a similar arrangement, traces another line
on the cylinder in which are indents corresponding to fixed distances
of travel along the tank, the indents being caused by small
projections which strike a trigger at the bottom of the carriage as it
passes, and make electric contact. From these time and distance
diagrams accurate account can be taken of the speed at which the model
and its supporting carriage have been driven. Thus on the same
cylinder is recorded graphically the speed and resistance of the
model. The carriage may be driven at any assigned speed by adjusting
the governor of the driving engine already alluded to, but the record
of the speed by means of the time and distance diagrams is more
definite. When the resistances of the model have been obtained at
several speeds, varying in some cases from 50 to 1,000 feet per
minute, the speeds are set off in suitable units along a base line,
and for every speed at which resistance is measured, the resistance is
set off to scale as an ordinate value at those speeds. A line passing
through these spots forms the "curve of resistance," from which the
resistance experienced by the model at the given trial speeds or any
intermediate speed can be ascertained. The resistance being known, the
power required to overcome resistance and drive the actual ship at any
given speed is easily deduced by applying the rule before described as
the law of comparison.--_The Steamship._

* * * * *

THE SHIP IN THE NEW FRENCH BALLET OF THE "TEMPEST."

A new ballet, entitled the "Tempest," by Mess