and Resistance of Vessels and other Moving Bodies.
Year: 1885

page_text: and Resistance of Vessels and other Moving Bodies.
I FRANK CAWS of 60 Fawcett Street Sunderland in the county of Durham
Architect do hereby declare the nature of my' invention for A NEW OR IMPROVED
RESISTANCE AND SPEED METER to be as follows:-
a
=
The object of my invention is to provide a mechanical contrivance or meter by
which any person of ordinary intelligence shall be able readily and speedily to
ascertain the resistance and consequently the power required to drive any ship or
other moving body at any given speed, the model of the ship or other body being
provided.
I attain the object mainly by an application of the laws of gravitation to one or
more pendant weights-where two or more weights are used one of them descends
vertically by its gravity and moves the other horizontally. The resistance of the
ship or other body opposes the horizontal motion and registers on a suitable scale,
the measure of retardation, and the relationship between the retardation and the
velocity and density of the descending weight gives all the required data for
arriving at the speed and power of the ship or other body. The relationship in
20
== velocity due to gravity.
Where the motive weight is dispensed with I substitute suitably arranged clock-
work or other motive power; or I may use the falling weight in combination with
the clockwork or other motive power.
In the particular application of the invention to the case of ships, I provide a
tank of any suitable length (say 20 feet) filled with water, in this I place the
model of the ship to be experimented upon; and, when a motive weight is used to
propel the model through the water, I suspend it over a frictionless pulley, by
means of a suitable cord attached to a carriage which it moves along on frictionless
rollers. To the carriage I hang a horizontal scale so arranged that a "jockey" or
pointer actuated by the suspended weight, which is retarded in its horizontal
course by the resistance of the ship shall be moved so as to register the amount of
ID 1

page_text: retardation due to the resistance of the model at any particular moment desired,
whether the speed be rising, falling or uniform. The motive weight which imparts
its power to the carriage is so suspended that when the experiment is commenced
it shall stand at nil on a vertical scale; a sliding bracket being attached below the
weight at any desired level on the scale at which the results are required to be
taken; upon which bracket the descending weight alights and is arrested.
To eliminate from the meter the disturbing element of friction, I provide a
suitable extra or counter-weight which exactly counterpoises the frictional inertia
of the carriage and its appendages..
As is well known the speed of a model is to the speed of the ship as the square
root of the number of times the scale of the ship exceeds the scale of the model:-
Thus in a model of full size the speed of the ship will be ✓ 48 = 6.9 times
the speed of the model-And further the resistance of the ship will be to the
resistance of the model as the cube of the number of times the scale of the ship
exceeds the scale of the model:-Thus for a ship 48 times the scale of the model
the resistance of the ship will be 483 times that of the model.
In the particular application of the invention to the case of ships; when (either
in addition to or instead of a motive weight) the power is supplied by clock work
or other motive contrivance, fixed within or upon the model and actuating a
propeller or propellers the pendant weight, pointer, and scale, register the resistance
and speed in a similar manner to that above described either in combination with
the vertical scale and its sliding bracket before specified, or with clockwork or
other motor index, or in combination with both the vertical scale and the index of
clockwork or other motor.
An Apparatus for Finding the Relations Between the Speed
and Resistance of Vessels and other Moving Bodies.
I FRANK CAWSs of 00 Fawcett Street Sunderland, in the county of Durham
Architect, do hereby declare the nature of my invention for A RESISTENCE AND
SPEED METER, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The object of my invention is to provide a mechanical contrivance or apparatus
which may be employed where the space at command is limited and at moderate
cost and by which any intelligent person shall be able readily and speedily to

page_text: ascertain the resistance of and consequently the power required to drive any ship
or other moving body at any given speed the model of the ship or other moving
body being provided together with the necessary tank of water or other medium
of motion as required.
I attain the object mainly by an application of the laws of gravitation to a
system of pendant weights and counterweights connected by lines or cords
(preferably of silk) ruuning over frictionless pulleys by which the model is
propelled and the distance run and the time occupied are registered and in some
cases by the additional aid of a resistance indicator or initiator.
In order to propel the model I attach to it a tow line, or in the event of the
initiator being used I attach the tow line to it and secure it to the model and
I fasten the other end of the tow line to one of the weights which I call the
motive weight which may be regulated to any required density; in order to register
the distance travelled by the model I fix a vertical scale in any convenient position
behind the motive weight (which falls by its own gravity) and I read off the
distance fallen by the weight, which is the distance run during the experiment,
an adjustable bracket upon which the weight falls being provided as an indicator.
I do not confine myself to the use of a motive weight as I may substitute clock work
or other motive power or I may make use of a combination of motors.
In order to register the time occupied by the run I make use of a second weight
which I call the time weight the object of which is to dispense with clocks or
other timekeepers (for where the whole operation is one of ouly a few seconds
these can hardly be read with sufficient accuracy) and I measure the time by the
distance which the time weight falls by its gravity checked by an ascending
weight of known proportional density. The relationship between the densties
of the time weight and the check weight rules the relationship between the
acceleration of the time weight and the acceleration of free gravity and is shown
by the following formula—
g=acceleration of free gravity.
Behind the time weight a vertical scale is fitted, with an adjustable bracket upon
which the weight falls, this bracket serves as an indicator by which the distance
through which the weight has fallen is read, and thus the precise time occupied
may be calculated.
Although I prefer to use a time weight I do not confine myself to this method
of registering time.
When the density of, and the distance fallen through by the motive weight are
known together with the time occupied by the experiment the resistance of the
model due to varying or steady speeds may be educed.
When it is desired to registed the resistances of the model by means of the
initiator I fasten it to the model and I attach the tow line to the pendulum or
spring or other moving part (according to the type of initiator employed) which is
deflected or extended, by the gravity of the motive weight and a pointer or jockey
which may be disengaged at any desired point; is moved to and fro on a suitable
scale, thus the resistance may be registered at any moment either at the point of
attaining uniform speed or at any subsequent point of uniform speed (when the
resistance and power are of course equal) or at any point of initiation or retarda-
tion when the power is in excess of the resistance or the resistance in excess of the
power.
:
In order to secure an absolutely simultaneous record of results I make use of an
electric circuit and electro-magnetic instruments.
Referring now to the accompanying drawing which illustrates the apparatus as
employed when experimenting upon the models of ships-I would not however,

page_text: have it understood that I confine myself to the particular mechanism herein
described and shown.
Figure 1 represents a general view of the apparatus complete.
Figures 2, 3, 4, 5, 6 and 7 are details.
.. Referring, then to the general view, A represents the tank of water B the model
of the ship to be experimented upon, C the tow line, which may be of silk, fine
wire or other suitable material; if fine insulated wire be used it may be employed
as the conductor of the electric current. I carry the line C over the pulleys D
and E, either or both of which may be arranged to run on frictionless rollers d as
shown in the brackets to the motive weight F which is graduated to the required
density, G is the scale and H the bracket by means of which the distances fallen
by F are guaged, the former being-marked with a graduated scale to represent any
desired distances such as feet knots or miles and fractions of same, the latter being
adjustable by the screw a, as shown more clearly in detail figure 2, to the greatest
exactitude. The vertical distance through which the weight F falls is the distance
run by the model during the experiment less the deflection or extension of initiator
index, when initiator is employed.
The time weight is represented by J it is connected to the counterweight K by
the line L of silk or other suitable material, which passes over the pulley M
arranged to run on frictionless rollers & similar to pulley E a small spring drum y
being provided for adjusting the length of the line L which below K is extended
and carried through a double eye or staple at N and used as a leash line for
holding the model B in position until all is ready for experimenting the friction of
Lin N aided by the resistance of the time weight being sufficient to prevent the
power or weight F from carrying the model forward until the leash is severed
which may be done by burning or otherwise when all is ready-Thus the severing
of the leash line frees the model with its motive weight at the same time that it
frees the time weight and a simultaneous start is effected a check line L' connected
to check weight K¹ is provided for taking the weight of J. immediatley it strikes P.
Below the time weight a guage O and bracket P are fitted similar to G and H
respectively but marked or graduated to show feet, minutes or seconds and
fractions of seconds, or as may be desired. By noting the exact distance fallen
through by the weight J the operator may learn the exact time occupied by the
model in arriving at any particular point of the run, whether it be during initiation
on attaining uniform speed or subsequently.
The electric battery is represented by Q by it the current is generated which
indicates the exact and simultaneous record of results. From Q I carry an
insulated wire R to the brackets H and P and thence to the indicator S and
switch T and when an initiator is employed I carry R to the ring U which may
be placed at any desired point upon the suspended wire tramway X and thence to
the disconnector V and the initiator I the return current passing through W which
may be twisted round R for the greater part of its length as shown. The point of
suspension of the ring U is dependant upon the distance run by the model and is
so adjusted that the oscillation of V shall not affect the speed of the model at the
points at which the results are to be taken. By means of the switch T which may
be of any usual type I connect or disconnect those parts of the apparatus which
I require or wish to dispense with, for the particular experiment in hand. The
different parts of the apparatus are so arranged that the electric signals may be
made either on making or breaking contact and any of the indicated results can be
taken by separate circuits or in one circuit as desired.
The initiator is represented by the letter I and when employed is fixed to the
model as shown. It may be of two kinds as shown in figures 4 and 5 the former
being of the spring and the latter of the pendulum type, or an overhead carriage
and swinging plummet may be used.
Referring now to the detail drawings―
Figure 2 represents the brackets H and P with their attachments. P¹ is the,
bracket and Or the vertical scale graduated as required a vernier & being attached

page_text: to the bracket. A screw a is provided which works in the nut o attached to P¹
the lower end being held as shown in the bracket or eyebolt j on the clamp h
(which may be secured in any desired position on O¹) by turning the handle i the
bracket P¹ may be adjusted to any required exactitude. On the face of P¹ a plug g
which may be of boxwood, ebonite, or any suitable nonconducting material is
provided having a metal zone k as shown are binding screws for attaching the
electric wire and m m are electric spring terminals which hold up the plug g, until
it is knocked down by the falling weights F or J as the case may be. As the
plug g descends the metal zone k passes through the electric terminals m and as it
passes connection is made and may be signalled on the electro-magnetic indicator S
figure 1. If it is desired to signal by breaking contact the plug g is set with the
electric zone between the terminals m and when knocked away by the weights
the current is broken and may be signalled on the indicator. A pad of blotting
paper or other suitable material may be fitted to the top of g to deaden the blows
of F or J.
Figure 3 represents one half of the indicator S the other being precisely similar
and both being contained in one case it consists of magnets a fixed to the frame b
and encased in coils of insulated copper wire, c is an armature hinged at d and
provided with a very small lip at e, which holds the lever h up so long as the
armature is not attracted by a. When the electric current passes to the magnets
(by means of the wires R and W not shown in this figure) the armature c is
attracted and h to which the signal disc is attached falls on its hinge at i and the
signal is given. The instrument may be arranged to signal the breaking of the
electric circuit, & being attracted by the magnets a while the current passes and
falling when it is broken. By means of the switch T I can make use of either half
of the indicator or of both together in one circuit.
Figures 4 and 5 represent two forms of indicator-Referring first to figure 4
n is the base plate of wood or other suitable material by which it is fixed to the
model a metal index c being secured to n, upon c a light ebonite jockey or
indicator u slides, to which a binding screw p for connecting the wire from the
battery is attached together with a screw q having a flat spring underneath for
pressing on the index bar and fixing it in any desired position when required and
which lifts and clears c when relieved of pressure-A horse shoe magnet rencased
in coils of insulated copper wire is carried on rollers 8 its ends heing bent down as
shown to reach the jockey: an armature carried by arms hinged to the clamp v
as shown being provided which rests in a bracket attached to the jockey u when
the electric current is off and carries the jockey forward and backward, and which
is lifted from the bracket when the current passes and leaves the jockey stationary.
A spring t is placed above the magnet r and one end is fixed to the block w on the
base plate n the opposite end being secured to the magnet by means of an ebonite
clamp a small disconnector v₁ of ebonite or other suitable nonconducting material
is provided by which connection between and u is prevented when desired. The
tow line C is secured to the clamp v by means of a small hook, and a wire passes
from little v through u to which the leash line L is secured. In order to read the
index with greater facility I provide a contrivance which I call an "enlarger" it
consists of a frame of ebonite a to which is fixed a dial b on the centre ca spear f
loaded at d is mounted e is a pin from which a festoon of silk or other suitable
material passes to p. As u moves to and fro the heavy end of the spear friding
on the festoon rises or falls and the slightest movement of the jockey may be
enlarged as desired. In working the instrument to signal on making contact at
the attainment of uniform speed I secure the jockey u at the limit of deflection of
the spring t (which depends upon the density of the motive weight employed) and
having attached the leash line I start the apparatus. During initiation if the
power be constant the clamp which starts from zero on the index c instantly
advances with diminishing acceleration to its maximum limit where u is fixed and
as the magnet poles touch the connecting terminals on u which are connected by a
wire-to-the-bending screw p the current passes and the desired signal given. If

page_text: through friction or from other cause the power is decreased v recedes from u and
returns again if the cause of reduction is removed. The jockey u may be fixed at
any point on c short of the limit of deflection and the moment of contact signalled.
In order to register the exact intensity of the power or the varying resistance at
any particular moment when the power is varying during initiation or otherwise
instead of fixing on the index bar c I place it against the poles of the magnet
and employ the hinged armature to hold it in position as above described and
prevent its being projected forward and disconnected from r by the first violent
jerk of the motive power: during this stage the action is mechanical but the
moment the power is detached an electric current passes and the armature ¹ is
lifted from its catch by magnetic attraction leaving in situ registering the desired
particulars. The armature may be lifted by mechanical means and the use of
electro-magnétism dispensed with altogether.
When the electric current is continuous and the point of breaking contact is to
be registered I leave the jockey u loose, it then follows the magnet as it moves to
and fro but remains stationary at the exact point at which contact is broken thus
registering the exact resistance at that point. Referring now to figure 5, n is a
frame of brass or other suitable material by which it is fixed to the model, a metal
index bar c being secured to n, upon c a light jockey u is fitted which may be
secured in any desired position by the screw q a binding screw p being provided
for connecting the wire from the battery. A pendulum r (shown more clearly
with its connections in Figure 6) is suspended from the centres v to which the
spears wand w¹ are connected, a spring buffer 8 being placed so as to prevent the
pendulum from swinging to and fro and disturbing the spears, while w follows
the pendulum to the limit of deflection and remains there w¹ moves to and fro
with the pendulum during initiation (when from the intervention of friction or
otherwise the power is not uniform) but is suddenly detached the moment the
motive power is detached the latter slacks the tow line and allows t t¹ which are
connected to x by the bars as shows which are always in line with the pull of the
tow rope, to swing on their centre y in the catch and push the catch on its
centre causing it to swing rapidly forward and release the spear w¹. The
pendulum and the spears ww work about the same centre v but are independant
of one another -A small disconnector v' of any suitable nonconducting material is
provided by which connection between and w¹ may be prevented when desired.
I attach the tow line C and the leash line L to t and t¹ respectively by means of
small books. In working the instrument to signal on making contact at the point
of attaining uniform speed I secure the jockey u at the limit of deflection of the
pendulum (dependant upon the density of the motive weight) and having made
the electric connections by the screws p and p¹ I start the apparatus. During
initiation if the power be constant the spear 2 starts from zero on the index o
instantly advances with diminishing acceleration following the deflection of the
pendulum till it reaches u and makes contact at which moment the desired signal
is given. If through the intervention of friction or otherwise the power fluctuates
the spear w¹ marks the fluctuations as they occur and at whatever instant the
power is removed the spear will stand in situ recording the power exerted at that
moment. But in these experiments the leash line must be attached to the stern of
the model not to the pendulum r, the pendulum starting at the point on c which
indicates the maximum power. The jockey may be fixed at any desired point on
the scale c short of the full deflection given to w¹ by the motive weight and the
moment of contact between w¹ and u signalled. This instrument may be used to
register the resistance at any desired point without the aid of electricity (in this
case the jockey u is not employed) the tow line C is attached to t and the apparatus
started, the spear w follows the motion of r but remains stationary at any point
of deflection on the sudden stopping of the motive weight and thus the exact
resistance at that point is registered on the scale c.
Referring now to figure 7 which represents the detacher or disconnector V, and
is an instrument required when an initiator is employed a a are electro magnets

page_text: encased in insulated copper wire and fixed to a central frame b, c c are armatures
hinged at d, the lower ends of which are made with lips at e which hold the
disconnecting piece h (to which the circuit wires to the initiator are secured by
screws) in place so long as c c are not attracted by a a. When the electric current
passes to the magnets by the wires R and W they attract the armatures which
with the assistance of the springs g open and the disconnecting piece h falls. The
instrument may be arranged to disconnect at the breaking of the electric circuit,
h being held in position by the attraction of the magnets while the current passes
and falling when it is broken.
In adjusting and working the apparatus the following relationships must be
borne in mind viz―
That the resistance of the full size ship is as many times greater than that of
the model as the cube of the scale of the model; also that the distance travelled
by the full sized ship is as the square root of the scale of the model multiplied by
the distance travelled by the model in the same time. These relationships are
however subject to modification due to non-equivalency of skin smoothness and
corrections based upon experiments must be made.
The method of operating when it is desired to find the speed at which a given
power will drive a given model is as follows
After adjusting the motive weight F to represent the power required I connect
it to the initiator I on the model B by the tow line C and note the exact deflection
shown on the initiator which is caused by the motive weight as already described.
I then connect the leash line L to the initiator and by it hold the model
stationary. The time weights J and K being adjusted, of known proportional
density and the former set to zero on the scale O, I set the bracket P to suit as
Dearly as I can judge or calculate the initial period due to the speed which will be
produced by the given power. I also set F at zero on the scale G and adjust H in
a similar manner to P to suit the initial period. I connect the brackets H and P
together with the detacher V and initiator I in the electric circuit from the
battery Q, to the signalling box S by means of the wires R and W and the switch T
and start the apparatus by burning or otherwise severing the leash line L then by
the signal S I note whether uniformn speed is indicated in the period allotted and
if not I repeat the experiment adjusting the brackets each time until the required
signal is given thus I learn that in a certain period and with a run of a certain
distance the model has reached uniform speed.
The length of initial run in attaining uniform speed when the power is a constant
weight acting over frictionless pulleys may be calculated by the laws of gravity
provided the mean value of variable acceleration is known, to ascertain this how-
ever reference to a specially prepared table is necessary, which will show certain
speeds with their initial times and distances; ascertained from actual experiment
as well as from theoretical calculations or otherwise.
When these tables are not employed a period of uniform speed run is required
to enable the operator to ascertain the imformation desired. Therefore having
learnt the points both of time and distance at which the model has attained
uniform speed I proceed as follows-First I disconnect the initiator I and its
connections-I then again set the weights F and J at zero on their respective
scales G and O. And then lower the time weight bracket P so as to give as many
seconds run at uniform speed as may be desired and then lower the motive weight
bracket H to give as nearly as I can judge the distance through which the weight F
will fall, during the time allowed. I then connect the electric apparatus and adjust
the bracket Has described until I get the signal showing that the weights F and J
have reached their respective brackets simultaneously. "I then note the total time
occupied and distance run in this second experiment, and I deduct from these the
time occupied and distance run in the first experiment. Thus I learn the time
occupied and distance run by the model at uniform speed with the known motive
weight.

page_text: i
When the tables above referred to are made use of a period of uniform speed run
may be dispensed with as the deductions obtained from the initial run will in this
case give the uniform speed attainable with the weight or power employed.
I do not confine myself to the method of operating as above described as the
apparatus is applicable to many other purposes such as establishing by, a series of
experimental analytical investigations the best form of vessel for use under, any
particular conditions and the best form of propeller under such conditions, also for
gauging the resistance arising from the submerged skin of vessel under various
conditions of smoothness, and for gauging the nature, and differing effects of fluid
resistance under varying speeds whether rising uniform or falling.
I make use largely of graphic form of analysis of the various results obtained
but algebraical formula may also be employed.
Having described the apparatus as fitted for testing ships models, I would not
have it understood that I confine myself to this application of the invention as it
is also applicable for testing other moving bodies. But in other cases a line of
rails or other medium of motion may be substituted for the tank.
:
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1. In an apparatus for finding the relations between the speed and resistance of
vessels and other moving bodies the application of gravity to the measurement of
distance and time substantially as and for the purposes shown and described.
2. The application of a selfregistering pendulum and also of a selfregistering
spring resistance indicator or initiator substantially as and for the purposes shown
and described.
3. In an apparatus for finding the relations between the speeds and resistances
of vessels, the use of electricity as a gauge of simultaneous action of the various
parts substantially as shown and described.
4. The application of electricity to register the resistance indicated on a spring
gauge or initiator substantially as shown and described.
5. The application of an enlarger to the indicator or initiator substantially as
and for the purposes shown and described.
6. The general arrangement of the various parts of the apparatus substantially
as and for the purposes shown and described.
TX
Ր. 1
1000