AN IMPROVED APPARATUS FOR INDICATING THE DISTANCE TRAVELLED BY A SHIP THROUGH THE WATER IN A GIVEN TIME, AND THE SPEED AT WHICH SHE IS TRAVELLING
Year: 1876

page_text: LETTERS PATENT to Robert Henry Armit, of No. 8, Westminster Chambers,
Victoria Street, in the County of Middlesex, retired Lieutenant in the Royal
Navy, for the Invention of "AN IMPROVED APPARATUS FOR INDICATING THE
DISTANCE TRAVELLED BY A SHIP THROUGH THE WATER IN A GIVEN TIME, AND
THE SPEED AT WHICH SHE IS TRAVELLING."
Scaled the 7th October 1876, in pursuance of an Order of the Lord Chancellor, and
PROVISIONAL SPECIFICATION left by Robert Henry Armit at the Office of
the Commissioners of Patents on the 9th March 1876.
ROBERT HENRY ARMIT, of No. 8, Westminster Chambers, Victoria Street, in the
County of Middlesex, retired Lieutenant in the Royal Navy. "AN IMPROVED
APPARATUS FOR INDICATING THE DISTANCE TRAVELLED BY A SHIP THROUGH THE
WATER IN A GIVEN TIME, AND THE SPEED AT WHICH SHE IS TRAVELLING."
The cylinder y in Figure 2 has a catgut string wound round it, with a length of
rope or line with a hook or clasp at the end thereof, to which a weight is suspended,
and the pressure of the water caused by the passage of the ship sets the mechanism
in motion by causing the cylinder y to revolve, and by means of the cogged wheel
at the base of the cylinder the pinion sets the wheels and pinions A, B, C, D, in
motion through the connecting pinions and wheels E, E, E, geared as in Figure 3.
Z, Z, Z, is a train of wheels and fly to regulate the speed of the revolutions of
the cylinder y. The catgut on cylinder y is wound or rewound by a key placed on
the square S as often as needful, according to the time for which the cylinder and
catgut are regulated. Instead of the cylinder and catgut a similar motion may be
obtained by means of springs, as in a clock. The pinions A, B, C, D, have leads
or indicators affixed to the axes, as in Figure 1. The indicator A is caused to
revolve once for every nautical mile, and the indicator B once for every ten miles,
nautical miles, and the indicator Conce for every one hundred nautical miles, and the
indicator D once for every one thousand nautical miles the ship moves through the
water.
I attach a tow line to the hook of an ordinary pulley wheel, Figure 4, with
guard to keep the catgut string in its place, and I couple the apparatus above
described to the mechanism of an ordinary spring weighing machine of which the
hand has been steadied by a ratchet, pinions and wheels, and fly. By means of the

page_text: pressure of a certain number of pounds weight of a given length of line and
weight at the end thereof towed through the water the speed of the ship at any
moment is indicated on the dial of the weighing machine. I find that the actual
pressure exerted by the water is in proportion to the thickness and length of rope
towed, the pressure therefrom increasing in the same ratio as the speed, for example,
a half pound weight attached to a silk thread twenty yards long will exert a
pressure of one and a-half pounds at a speed of eight knots an hour, and a line
three-sixteenths of an inch in diameter and two hundred feet long without a
weight attached will exert a pressure of about fourteen pounds, and if a half
pound weight be attached to such line the pressure will be increased to fifteen and
a-half pounds, and if a six pounds weight be attached to such line the pressure
will be increased in like proportion, videlicet, thirty-one pounds.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Henry Armit in the Great Seal Patent Office on the 9th
October 1876.
ROBERT HENRY ARMIT, of No. 8, Westminster Chambers, Victoria Street, in the
"AN IMPROVED
County of Middlesex, retired Lieutenant in the Royal Navy.
APPARATUS FOR INDICATING THE DISTANCE TRAVELLED BY A SHIP THROUGH THE
WATER IN A GIVEN TIME, AND THE SPEED AT WHICH SHE IS TRAVELLING."
The cylinder, barrel, or tumbler, herein-after called the barrel Y in Figure 2, has a
catgut, silk, or other cord or metal chain, herein-after called the chain, wound round
it, and attached to a length of rope, herein-after called the log line, by a hook or
clasp at the end thereof, to which a weight may be suspended if it be desired to
shorten the log line by reducing its length by the equivalent of the said weight or
otherwise. The strain on the log line causes the barrel or barrels, if more than one,
to revolve. By means of a cogged wheel at the base of the barrel the pinion X is
made to revolve and set the wheels and pinions A, B, C, in motion, through the
connecting pinions and wheels E, E, E, geared as in Figures 3 and 5, but when two
or more barrels are used the motor or first barrel y¹ sets these pinions in motion,
while the supply or feed barrel y works a regulating train of wheels so constructed
as to cause the hand or hands of the registering log to work accurately; Z1, Z2, Z3, Z³,
shew such a train of wheels for that purpose.
The chain or barrel y or y² is wound or rewound by a key, Figure 10, placed on
the square K according to the time for which the barrel and chain are regulated, or
a similar motion may be obtained by means of springs and levers as in a clock.
The pinions A, B, C, have heads or indicators affixed to the axes, as in Figure 1,
and are geared by means of a train of reducing wheels worked by the cogs of the
motor barrel; for example, should there be 6 cogs on the pinion worked by the
motor barrel, they should work into a wheel having 24 cogs; if the pinion of this
wheel has six cogs it should work into a wheel of 60 cogs, and all the other wheels
and pinions should be cut in the like proportion by tenths.
The indicator A, Figure 1, is caused to revolve once for every nautical mile, and
the indicator B once for every ten nautical miles, and the indicator C once for every
one hundred nautical miles, and so on to higher numbers. Or instead of four dials
one only may be used, with one hand indicating the number of miles or knots
traversed, the dial plate being graduated for that purpose from one up to 50 or
100, or higher number of nautical miles; in that case graduated wheels need not
be used. I can attach a log line to the ring of an ordinary pulley wheel, as shewn
in Figure 9, with guard to keep the chain in its place, and I can couple the
apparatus above described to the mechanism of an ordinary spring weighing
machine of accurate construction. The hand of the weighing machine should be
steadied by wheels or pulleys and fly, as shewn at Figure 5 at B, b, b, b, b, worked
by pulley wheel P and chain c, c, c, c. By means of the strain on the log line the

page_text: speed of the ship at any moment is indicated on the dial B, Figure 6, of the.
weighing machine; the distance made good being registered on the dial A graduated
to the number of miles for which the works are regulated.
I now proceed to explain. The actual strain or pressure exerted by the water on
any weight, whether consisting of a length of rope or other substance, is in pro-
portion to the speed at which that substance is towed, the strain on the line,
whether weighted or not weighted, increasing in the same ratio as the speed. I
have found that a half-pound weight attached to a silk thread twenty yards long
will weigh three half pounds at a speed of eight knots an hour, and that a line
three-sixteenths of an inch in diameter and two hundred feet long, weighing 28
ounces without a weight attached, will weigh about fourteen pounds when towed at
the same speed through the water, and that if a half-pound weight be attached to
such line the pressure will be increased to fifteen and a half pounds, and that if a
six pounds weight be attached to such line the strain will be increased in like
proportion, videlicit, to thirty-two pounds, and that if a length of line weighing six:
pounds be attached the strain will also be increased in like proportion, videlicit, to
thirty-two pounds, and that the strain on the tow line will increase or decrease
according as the speed of the ship is increased or decreased, but that when 28
ounces only are used the strain will multiply with the speed, as indicated in the:
following table which is given as an example.
proportion to its normal weight.
UI 10:59 CITIT 28 ounces the strain will vary in
Instead of employing a spring balance, as shewn in the Drawings. When I
employ springs and levers to set the log in motion, I place the works similar to
those of a lever clock in a case, and to the works of the clock I attach a quadrant
rack to gear into a spring balance consisting of a semicircular flat spring secured to
the inner circumference of the case, and one end of the spring is by means of tho
chain attached to a fusce on the speed indicator pinion; that pinion is worked by
means of the quadrant rack. The log line is attached to the rack by means of a
chain. The strain on the spring of the weighing machine regulates by a lever
escapement the motion of a train of wheels passing through the clockwork, and
forming a series of reducing wheels which are worked off the barrel; these reducing
wheels are connected by a cogged wheel to an index pinion on the opposite side of
the clock. On this pinion is a hand which is moved round the distance dial, and so
indicates the distance travelled by the vessel through the water.
The same
clockwork can be readily made to record on the dial plate the exact time of day
and the time at which the log was set, the motion of the whole being regulated by
the strain on the log line as registered on the speed indicator having the spring
balance.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 represents the dial plate of a log to register 100 miles by means of the

page_text: Fig. 2 represents a sectional view of the mechanism which works the hands A, B, C,
in Fig. 1. Y is the barrel with winding up gear and cogged wheel attached.
Round the barrel Y is wound a chain to which is attached the log line to be towed;
the cogged wheel of this barrel is made to revolve by the strain on the chain which
causes the pinion x to rotate. Into this pinion is geared the connecting cogged
wheel E, by means of which the wheels and pinions A, E, B, E, C, etc., are made to
work. At the base of the pinion is a cogged wheel which works the train of
regulating wheels Z, Z, Z", terminating in a fan or fly wheel Zu
Fig. 3 represents a face view of the wheels and pinions x, E, E, E, and A, B, C.
Fig. 4 represents the barrel Y.
Fig. 5 represents a face view of the interior of the log.
Fig. 6 represents the dial plates taken off Fig. 5.
Fig. 7 represents the barrel y rigged to work an endless screw.
Fig. S represents the barrel y rigged to carry the chain c, c, c, c, and to work the
regulating wheels Z, Z, Z, and the fan or fly Z¹¹.
Fig. 9 represents the pulley wheel connecting the spring balance to the distance
dial.
Fig. 10 represents the key, by means of which my Invention is wound or
rewound.
Fig. 11 is a face view of the interior of the barrel when worked by means of a
spring.
Figs. 12 and 13 represent other means of working the distance dial.
Having described the nature of iny said Invention and in what manner the same
can be performed, I wish it to be understood that I do not claim any of the parts
taken separately, but that what claim as my Invention is, the new combination
of known parts, substantially as herein-before described as an improved apparatus
for indicating the distance travelled by a ship through the water in a given time,
and the speed at which she is travelling.
In witness whereof, I, the said Robert Henry Armit, have hereunto set my
hand and seal, this Ninth day of October, in the year of our Lord One
thousand eight hundred and seventy-six.
Signed, sealed, and delivered, by
the above-named Robert Henry
Armit, in the presence of
JI. WICKENS,
Solicitor,
ROBERT HENRY ARMIT. (L.S.)
96, Palmerston Buildings,
Old Broad Street,
London.