IMPROVED APPARATUS FOR MEASURING AND INDICATING THE RATE OF MOTION OF A SHIP OR OTHER BODY THROUGH WATER, AND THE SPEED OF CURRENTS OF WATER OR LIQUIDS
Year: 1871

page_text: LETTERS PATENT to Alfred Evans Fletcher, of Liverpool, in the
County of Lancaster, Government Inspector of Alkali Works for
the Western District, for the Invention of "IMPROVED APPARATUS FOR
MEASURING AND INDICATING THE RATE OF MOTION OF A SHIP OR OTHER BODY
THROUGH WATER, AND THE SPEED OF CURRENTS OF WATER OR
LIQUIDS."
OTHER
Sealed the 13th June 1871, and dated the 17th February 1871.
PROVISIONAL SPECIFICATION left by the said Alfred Evans Fletcher
at the Office of the Commissioners of Patents, with his Petition,
on the 17th February 1871.
I, ALFRED EVANS FLETCHER, of Liverpool, in the County of Lan-
5 caster, Government Inspecter of Alkali Works for the Western District,
do hereby declare the nature of the said Invention for "IMPROved Appa-

page_text: RATUS FOR MEASURING AND INDICATING THE RATE OF MOTION OF A SHIP OB
OTHER BODY THROUGH WATER, AND THE SPEED OF CURRENTS OF WATER OR
OTHER LIQUIDS," to bo as follows :-
My Invention relates to apparatus for accurately ascertaining the
rate of motion of a ship or other vessel or body through water by
persons on the said ship, vessel, or body, and also for accurately
ascertaining the speed of currents in rivers, pipes, or other ways past
fixed points.
The said rate or speed is ascertained by measuring the distance
between the heights or levels to which two columns of water or other
liquid rise or are assisted to rise in the apparatus. Or by observing the
motion of an index influenced by the height of these columns.
The apparatus may be described as consisting of three principal parts.
First, of nozzles or terminations which are placed in the water or
exposed to the current; one of these nozzles or terminations has an
opening facing the direction in which the vessel is progressing, or from
which the current is flowing, and the other has an opening facing the
opposite direction, or else facing downwards. Second, of pipes, tubes, or
ducts leading from each of the aforesaid nozzles or terminations to thic
indicator. Third, this consists of the indicator when employed for slow
speeds, of glass tubes connected with the said pipes, tubes, or ducts,
formed at the upper part with spaces or a space for collecting any air
which may enter with the water; the said upper part is provided with
a pump or other exhausting appliance for withdrawing the air equally
from over both columns of water or for forming a partial vacuum. Taps
or cocks are fitted in the upper part where necessary. The said
indicator which is by preference swung in gimbals, may be placed in
the cabin or saloon on board ship, or in any other convenient position,
either under or above the water line. When used on land to indicato
the speed of currents past fixed points, it is placed convenient for
obscrvation.
Indicators for high speeds are constructed with spaces or a space for
air, provided with an exhausting pump or its equivalent to withdraw air
equally from over both columns, and fitted with stop-cocks or taps, but
instead of having the glass tubes above described for low speeds, a U or

page_text: bent glass tube or its equivalent partially filled with quicksilver is
employed so as to bring the variations of the height or level of the
columns within easily readable limits. The ends of the said U or other
tube or its equivalent are connected with the pipes, tubes, or ducts.
The water columns are thereby allowed to act by direct contact on the
quicksilver. When it is desired to indicate the variations of speed by a
pointer or dial moving with an axis, I place floats on the surface of the
quicksilver and carry a cord from them over a pulley. The axis of the
pulley carries the pointer or dial. The variations of level of the water
or quicksilver in either of the indicators may be caused to form a con-
tinuous register of speed by giving motion to floats and transmitting
that motion, say, to a pencil in contact with a ribband of paper made to
move by clockwork.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alfred Evans Fletcher in the Great Seal Patent
Office on the 16th August 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Alfred
EVANS FLETCHER, of Liverpool, in the County of Lancaster, Government
Inspector of Alkali Works for the Western District, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventeenth day of February, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fourth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Alfred Evans Fletcher, Her
special licence that I, the said Alfred Evans Fletcher, my executors,
administrators, and assigns, or such others as I, the said Alfred Evans
Fletcher, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVED APPARATUS FOR MEASURING AND INDICATING THE RATE OF MOTION
OF A SHIP OR OTHER BODY THROUGH WATER AND THE SPEED OF CURRENTS OF

page_text: bent or formed that the current of water passes across its open end, or it
may be in any position intermediate to these two.
Fig. 1 shows in side elevation two tubes with the ends bent in opposite
directions; Fig. 2 shews in side elevation one tube straight, the other
bent, so as to face in a direction up the stream of water to be measured ;
Fig. 3 is a compound speed tube drawn in side clevation, one tube being
placed within the other; the inner tube has a plain end opening down-
wards; Fig. 4 is a compound speed tube, also drawn in side elevation,
the tubes being made in one piece; Fig. 5 is a transverse section at the
line Z, Z.
The tubes or the compound tube, hereafter for convenience called
speed tubes or speed tube, are so held in the stream of water that the
nozzles or ends of the tubes are exposed to the force of the current.
The apper ends of the tubes are connected by tubing with the indicator.
the
The said indicator consists of two straight vertical glass tubes a,
lower ends of which are connected with the tubes 6 last mentioned, the
upper ends are connected with an exhausting pump c.
A convenient form of indicator is shewn in front elevation by Fig. 6.
A few strokes of the exhausting pump c will bring the water up into the
glass tubes a of the indicator, where it will stand level if the speed tube
dips into still water, but if the water is flowing the column in connection
with that orifice in the speed tube which is directed up the stream will
stand higher than the other column. This difference can be conveniently
measured by the scales of the instrument and the velocity of the stream
found in following table, marked No. 1.

page_text: When it is required to measure the velocity of water or other liquids
flowing through pipes a cock d with a stuffing box e, as shown in
vertical section and elevation by Fig. 7, and transverse section on the
line Y, Y, by Fig. 8, should be screwed into the pipe at places where the
speed is to be measured. The speed tube a is better mado flat, as shewn
in the Drawing, so as not to interfere much with the flow of the liquid
in the pipe. The speed tube should be thrust into the pipe so far as will
bring the orifices, to a distance from either side of the pipe equal to
one-sixth the internal diameter of the pipe. Thus if the pipe is 12
inches internal diameter the orifices should be either 2 or 10 inches
clear inside it. The nozzles g. 9, at the upper end of the speed tube
must be connected by tubing with the nozzles b, b, of the indicator. If
the liquid in the pipe is under pressure the exhausting pump e will not
be required, and can be removed. On opening the tap a portion of
the flowing liquid in the pipe will rise into the vertical glass tubes a
of the indicator. The tap should be closed before all the air has
been expelled from the indicator, so as to place the heads of the
columns of liquid in a convenient place for measuring. As in the
case of the open stream the difference of level can be measured by
the graduated scales of the instrument and the speed of the current
found in Table No. 1.
When the rhysimeter is applied to measuring the speed of a ship at
sca, speed tubes or a compound speed tube similar in construction to
those above described, are employed. The terminal nozzles must be
held in the water outside the ship cither by passing down outside
or through the ship's side or bottom. In cither of the latter cases an
arrangement such as is shown by Figs. 9 and 10, which are views in
side elevation and vertical section, Fig. 11, a longitudinal section at the
line X, X, and Fig. 12, a vertical section at the line W, W, may be
employed. is a cock of brass or other material having at the top a
stuffing box j, and at the bottom a plate, which can be attached to the
inner side of the skin of the ship. The speed tube m will pass through
both the stuffing boxj and the cock i, and so can be made to project,
more or less into the water, or can be removed altogether without
admitting any water to the ship. To assist in moving the speed tube m
up or down a rack and pinion o can be used, as is shewn in the Drawing.
Stulling boxes p are also provided at the top of the speed tube to allow

page_text: for the same motion there. Through these an uninterrupted com-
munication is maintained between the water in cach channel of the
speed tube by means of two connecting pipes of small bore T to the
indicator, which may be fixed in the cabin or other convenient place.
These connecting pipes 7 may be conveniently made of copper of
inch internal diameter.
An indicator of the same form as described and illustrated by Fig. 6
may be used, but unless the speed of the ship is very low the glass tubes
and the scales of the instrument would have to be inconveniently long.
To avoid this I introduce between the vertical tubes a, a, of the indi-
cator a U shaped tube e containing mercury, as shown by Fig. 13, and
cocks 8, or only one cock. Receptacles for air are placed or formed
at the tops of the water columns, so that any air which has gained
admission may collect in them and be readily removed by the exhausting
pump.
In the practical construction of the instrument it is found con-
venient to swell out one limb of the U tube containing mercury, and
so cause the whole column to be shown in one tube, and not the
half of it in each tube. This is shewn by the dotted lines u in
Fig. 13. By the help of the following table.marked No. 2 a scale
can be marked and fixed against the tube containing mercury, so as
to show at every varying height of the mercury the speed to which
tho ship has attained.

page_text: To compensate for the motion of the ship the indicator can be swung
in gimbals, the connections being made either with flexible tubing or
with ground air-tight joints.
Fig. 14 shows the external form of a ship's indicator with single
mercurial column. parc small discs of glass fixed in the sides of the 5
air vessels at the tops of the water columns. By means of the ex-
hausting pump c the air is removed from the air vessels l, t, through
the two-way cock to until the water riscs from the sca and fills them,
and by c any air which subsequently collects can be easily removed.

page_text: are the tubes which connect with the speed tube below. If it is
preferred that the indication of the speed should be shown on a dial
instead of by columns of water or mercury this can be done by con-
necting the pointer through the cords, chains, or rods, with floats resting
on the mercury or the water in the indicator columns. It may also be
made self-registering by the methods which are in use for that purpose
in other instruments. For instance, by means of floats motion may be
given to a pencil which pressing against or periodically made to touch
the surface of a cylinder of paper revolving by clockwork will by a line
or by a series of points continually record the speed of the ship. Or
motion may be given to a counting index, so that the number at any
time shewn will be proportionate to the distance travelled.
I would have it understood that in those parts of my said apparatus
which are exposed to atmospheric influence I propose to place glycerine
or other non-freezing liquid.
Having now described the nature of my said Invention, and par-
ticularized the same in such manner that others will be enabled to
carry my improvements into effect, I claim the improved apparatus for
measuring and indicating speed, substantially as described and illustrated
for the purposes set forth.
In witness whercof, I, the said Alfred Evans Fletcher, have hereunto
set my hand and scal, the Third day of August, in the year of
our Lord One thousand eight hundred and seventy-onc.
5 In the
presence
of
JOHN MAYER.
ALFRED E. FLETCHER. (L.S.)