IMPROVEMENTS IN INSTRUMENTS FOR TIMING SHIPS' Logs
Year: 1869

page_text: LETTERS PATENT to John Smith, Manager to Messrs. M. F. Dent & Co.,
Chronometer, Watch, and Clock Makers, of Nos. 33 and 34,
Cockspur St., Charing Cross, in the County of Middlesex, for the
Invention of "IMPROVEMENTS IN INSTRUMENTS FOR TIMING SHIPS'
Logs."
Scaled the 29th March 1870, and dated the 13th October 1869.
PROVISIONAL SPECIFICATION left by the said John Smith at the
Office of the Commissioners of Patents, with his Petition, on the
13th October 1869.
I, JOHN SMITH, Manager to Messrs. M. F. Dent & Co., Chronometer,
Watch, and Clock Makers, of Nos. 33 and 34, Cockspur St., Charing
Cross, in the County of Middlesex, do hereby declare the nature of the
said Invention for " IMPROVEMENTS IN INSTRUMENTS FOR TIMING SHIPS' LOGS,"
to be as follows:-
This Invention has for its object improvements in instruments for
timing ships' logs. At the present time it is usual to measure the

page_text: interval during which the log line is allowed to run out by means of a
sand glass, but this is inconvenient, especially at night, and it is deficient
in accuracy.
According to my Invention I construct a time measurer in such
manner as to give an audible signal at a certain prearranged time after
a finger key has been depressed. The bell may be caused to sound 14
seconds after the finger key has been depressed, or at other convenient
interval of time. The instrument as I prefer to construct it consists of
a mainspring actuating through a train of wheels an escapement wheel
into which an anchor escapement works. This escapement is governed
by means of an arm on its axis, which in vibrating beats up against
stops, one on either side, and which are adjusted nearer to or further
from each other to regulate the time of the instrument. The first or
slowest wheel of the train has a snail cam or wheel upon its axis, and a
notch is formed in this wheel at the bottom of the incline where it
approaches most nearly to the axis. The end of a detent lever enters
this notch and locks the train of wheels, until by depressing the
finger key the detent lever is lifted; then immediately the train of wheels
begins to run. The snail wheel as it revolves raises the detent lever
against the resistance of a spring with which it is provided, and on the
axis of the detont lever is a hammer, which is thus simultaneously
raised. When by the rotation of the snail wheel the fall upon it is
brought to the nose of the detent lever; this lever with the hammer
immediately returns, the hammer strikes upon a bell, and at the same
time the train of wheels is stopped. The mainspring may be wound in
the ordinary manner, or the depression of the finger may in addition to
liberating the train of wheels be also caused to wind the mainspring. A
stop wheel is provided, which both prevents the mainspring being over-
wound and also prevents the train running when the spring has become
so far unwound as to be too weak to maintain the proper rate of speed.

page_text: Clock Makers, of Nos. 33 and 34, Cockspur Street, Charing Cross, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of October, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Ier heirs and successors, give
and grant unto me, the said John Smith, Her special licence, that I,
the said John Smith, my executors, administrators, and assigns, or
such others as I, the said John Smith, my executors, administrators,
and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed,
should and lawfully might make, usc, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN INSTRUMENTS FOR
TIMING SHIPS' LOGS," upon the condition (amongst others) that I, the said
John Smith, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and scals, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Smith, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say :-
This Invention has for its object improvements in instruments for
timing ships' logs. At the present time it is usual to measure the
interval during which the log line is allowed to run out by means of a
sand glass, but this is inconvenient, especially at night, and it is deficient
in accuracy.
According to my Invention I construct a time measurer in such
manner as to give an audible signal at a certain prearranged time after a
push piece has been pressed in. The bell may be caused to sound 14
seconds after the push piece has been pressed in, or at other interval
of time.
The instrument as I prefer to construct it is shown at Figures 1 and 2.
It consists of a mainspring in a spring box a acting through a train
of wheels, seen in Figure 1, on an escapement wheel b into which

page_text: an anchor escapement work. This escapement is governed by means
of an arm & on its axis, which in vibrating beats up against stops e, e,
one on either side, and which are adjusted nearer to or further from each
other to regulate the time of the instrument. The first or slowest wheel
of the train, or that on the spring box a, has a snail cam or wheel f
upon its axis, and a notch may be formed in this wheel at f' at the
bottom of the incline where it approaches most nearly to the axis. The
end of a detent lever g then enters this notch and locks the train of
wheels, until by depressing the push piece the detent lever is lifted;
then immediately the train of wheels begins to run. The snail as it
revolves raises the detent lever 9 against the resistance of a spring with
which it is provided, and on the axis of the detent lever g is a hammer i,
which is thus simultaneously raised. When by the rotation of the snail
the most elevated part of it passes the bearing point of the detent lever g,
this lever with the hammer immediately returns, the hammer strikes
upon a bell, and at the same time the train of wheels is stopped. In
place of arranging the ends of the detent lever g to drop into a notch
at in the snail wheel, an arm 9* may be provided fastened on the
lever to act with a pin on the escapement wheel, and so stop the
running of the train. This latter arrangement is preferred. A stop
wheel is provided, which both prevents the mainspring being overwound,
and also prevents the train running when the spring has become so far
unwound as to be too weak to maintain the proper rate of speed. The
mainspring is wound in the ordinary manner. Instruments may also be
constructed in which the push piece in addition to liberating the train
of wheels may wind the spring.
The Drawing Figure 2 shows an instrument requiring no winding other
than is accomplished by the use of the push piece. A, A, is a brass box;
B is a push piece that goes through the box and the cock or support C,
and acts on an arm rivetted on an arbor, on the lower end of which is
rivetted the curved rack D. This rack acts in a pinion fixed to a stop
wheel with a single notch in it, with which works a click placed on the
escape wheel E, and this pinion and stop wheel turns on the arbor
of E. The rack has fifteen teeth and the pinion twelve, and when the
push piece is pressed in, the pinion with the stop wheel is turned upon
its axis a little more round than one full turn, and in returning through
the action of the click turns the escape wheel E. F is a hammer lifted by
an arm on the rack when the push piece is pressed in, and G is the bell

page_text: spring on which the hammer strikes; H is the balance; I, the balance
cock or support; K, the balance spring stud; L is a lever moveable on
the centro L'; M is a piece jointed on the end of the lever L; it serves
to retain the hammer when raised; the hammer having a notch in which
a pin M' in the moveable piece M falls when the hammer is lifted up.
This lever and moveable piece fall against pins, and are provided with
springs to bring them to the position in which the Drawing shows them.
L' is a spring on the lever L, the point of which drops into a hole in the
periphery of the balance; P is the spring of the push piece, and O
and N, the rack and hammer springs. When the push piece is pressed
in the rack moves to the left, and thereby turns the pinion with tho
stop wheel underneath the escape wheel a little more than one turn
back; the hammer at the same time moves to the right and hooks itself
on the pin M' in the moveable piece M. When the finger is then taken
off the push picce the rack and hammer move a little forward by the
action of their springs until the click on the escape wheel stops in
the notch on the stop wheel. The hammer by this action draws the
lever L forward, whereby the balance is set at liberty and allows the
wheel E by the pressure of the rack spring upon the rack to turn round
until a piu E placed on the wheel gets in contact with the end of the
picce M, whereby the pin that supported the hammer is drawn out of
the notch; the hammer then falls, and the lever L, which is acted on by
a small spring, again flies in and stops the balance. The escape wheel
has 28 teeth, and makes a revolution in 14 seconds. The seconds are
indicated by a hand on the dial.
Another modification of the instrument is shown at Figures 4 and 5.
The frame consists of a top and bottom plate a and b connected together
by pillars in the usual way. In Figure 4 the parts are seen which are
mounted on the top of the upper plate, and in Figure 5 the parts which
are between the plates. c is a slide connected with the plate a by
screws a', a', passing through slotted holes of a length to allow of the
requisite extent of motion; c' is a click on the slide c provided with a
spring c; it acts on the ratchet wheel d on the spring barrel, so that by
repeatedly pulling out the slide c the spring is wound. A stop finger is
employed to prevent overwinding. d' is a wheel on the spring barrel
gearing with a pinion e on an axis e', which if desired may also carry a
hand indicating the seconds on a dial, round which it travels in
56 seconds. is a spur wheel on the axis e' gearing with a pinion on

page_text: the intermediate axis f, which also carries the wheel
gearing with a
pinion g' on the axis of the escapement wheel g, on which an ordinary
lever escapement works; is the balance, and h'a pin, on its periphery,
and a stop i¹ on the lever i stands in the way of this pin until by pressure
on the button; the lever is lifted; is the axis of the lever i, and the
stop is a flat spring capable of yielding upwards, but not in the
contrary direction, so that when the stop i is dropped in after the train
has been running it may always catch the pin on the balance on the
upper side; k is a lever turning on a centre at k', and provided with a
spring, which when the lever i is moved to release the balance drops
in under its end and supports it; e, e, are four pins on the wheel e³, onc
or other of which as the train runs is brought against the arm m, which
is upon the same axis with the hammer m', and lifts the hammer.
When the pin passes the arm m the hammer falls by the action of the
spring mand strikes a bell, which for the sake of clearness is omitted in
the Drawing. m³ is a finger on the same axis with the hammer, and which
as the hammer is raised also rises past the end of the lever k, the small
spring * fixed on the lever yielding to allow it to pass. When the
hammer falls the finger m² descends upon the spring k*, which is unable
to yield in a downward direction, and so the lever k is moved until the
lever i is freed. The spring of this lever then at once causes it to return,
and the balance is stopped.
In witness whereof, I, the said John Smith, have hereunto set
my hand and scal, this 22nd day of March, in the year of our
Lord One thousand eight hundred and seventy.