IMPROVEMENTS IN APPARATUS FOR MEASURING AND RECORDING THE VELOCITY OF SHIPS, CURRENTS, AND MACHINERY
Year: 1883

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PROVISIONAL SPECIFICATION left by Arthur Temple Hopetown Scott at
the Office of the Commissioners of Patents on the 5th May 1883.
Communicated to him from abroad by James Marmaduke Langdale of Rue
de Grenelle Paris in the Republic of France
ARTHUR TEMPLE HOPETOWN SCOTT of the Trinity House in the County of
Middlesex, "IMPROVEMENTS IN APPARATUS FOR MEASURING AND RECORDING THE
VELOCITY OF SHIPS, CURRENTS, AND MACHINERY," a communication to me from
abroad by James Marmaduke Langdale of Rue de Grenelle Paris in the Republic
of France,
These improvements have for their object the indication at any required time of
the speed per hour, in knots and tenths or other arranged for time and
measurement at which a vessel is travelling or a current running, and the said
improvements also apply to the indication of the number of revolutions per minute,
or other arranged for time, at which the screw shaft or axle of a propeller or any
machine shaft is revolving.
For these purposes I employ a fan capable of being rotated similar to that of
the ordinary ships mechanical log, it is towed by an insulated wire, and revolves
about a cylinder containing a make and break contact arrangement.
The cylinder is pointed at one end, on the outside it has a series of small wheels
on which the fan revolves. At its point is an ebonite plug through which the
copper insulated towing wire is taken in such a manner as to insure its insulation
from the remainder of the cylinder and also to hermetically seal that opening.
This copper wire is taken to a platanized brass spring which is also insulated by
ebonite from the cylinder.
In the direction of its longer axis and at a distance from the point of the
cylinder, is a hermetically sealed partition, recessed on the side anterior to the
point of the cylinder in order to form á bearing for the main shaft.
This partition has a hole in it at side of its centre and is closed against the entry
of water by means of a flexible tube sealed at the end. Inside this tube is a bar
or lever pivotted at whatever point may be most convenient, one end of it closely
fits the tube the other has a platanized toe, and its length is such that this toe
shall be immediately over the platanized brass spring before mentioned.

page_text: Journaled in the partition and running through the entire length of the cylinder
is a shaft, having an eccentric in it, in such a position that it is immediately under
the end of the flexible tube.
The cylinder is made in two pieces screwed together, and the fan is secured to
the shaft by means of screws, so that the fan can be removed and the cylinder
unscrewed.
The towing wire I use is of such a nature as not to allow of torsion; as the log
is dragged through the water the fans are revolved, the fans being in connection
with the main shaft cause it to revolve and in its revolution the eccentric on it
presses against the tube which, yielding allows the end of the lever to move away
from the shaft, which causes its other platanized extremity, to make contact with
the platanized insulated brass spring which, as before mentioned is in connection
with the copper towing wire. Therefore for every revolution of the fan a contact
will take place between the toe of the lever and the spring.
The towing wire is put in connection with the positive pole of a battery which
works the registering apparatus, and the lever is in connection with the body of
the cylinder.
The tube should be made, either of corrugated metal, plain metal, india rubber,
india rubber and metal, or any material which would, while excluding the water
from the compartment, be flexible and lasting. The tube is made to unscrew in
order to allow a new tube readily to be put in should one break or give out.
The speed of the ship is obtained by the following apparatus.
In the circuit between a suitable recording instrument and the towing wire, is
placed a glass holding mercury and so arranged, that only while the glass is
inverted and the mercury flowing from one side to the other, can the electricity
pass to the recording machine.
The time that the mercury takes to run through, during every revolution of the
fan is shown or recorded, on the face of a conveniently arranged dial, which is
graduated according to the duration of time the mercury takes to run through, and
the pitch of the rotating fans, its reading being made to give knots and tenths
or other arranged for measurements.
For indicating the speed at which the propeller or any shaft is revolving-I fix
on the shaft 12 or any convenient number of contact pieces, opposite to them an
insulated contact is placed in such a position that in one revolution of the screw
each of these 12 contacts will successively rub against the insulated contact; an
insulated wire would be taken from the before mentioned insulated contact to the
recording instrument, so that while the mercury was running through the glass,
for every revolution of the screw shaft the recording instrument would be operated
on 12 times.
For making and breaking the above electrical contacts any convenient devices
can be employed, combined with a simple step by step recorder, having a dial and
pointer And in some cases the apparatus can be made to work automatically by
means of an acting clock movement arranged to invert periodically the mercurial
time glass Also for recording a tape suitably put in inotion can be employed,
and a pricker attached to the armature of an electro magnet, for making punctures
in said tape every time the glass is inverted.