A MARINE ALARUM CHRONOMETER FOR ASCERTAINING THE TIME OF A SHIP'S LOG LINE RUNNING OUT, THE TIME OF THE WATCHES ON SHIPBOARD, AND MANY OTHER USEFUL PURPOSES
Year: 1805

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DE LAFONS, of Threadneedle Street, in the City of London, Watchmaker,
send greeting..
WHEREAS His present most Excellent Majesty King George the Third, in
and by His Royal Letters Patent under the Great Seal of the United Kingdom
of Great Britain and Ireland, bearing date at Westminster, the Nineteenth day
of November, in the forty-sixth year of His reign, for Himself, His heirs and
successors, did give and grant unto me, the said John De Lafons, my executors,
administrators, and assigns, His especial licence, full power, sole prividege and
authority, that I, the said John De Lafons, my executors, administrators, and
assigns, and every of them, by myself and themselves, or by my or their deputy
or deputies, servants or agents, or such others as I, the said John De Lafons,
my executors, administrators, or assigns, should at any time agree with, and
no others, from time to time and at all times thereafter during the term of
years therein expressed, should and lawfully might make, use, exercise, and vend,
within that part of His said Majesty's said United Kingdom called England,
His Dominion of Wales, and Town of Berwick-upon-Tweed, my Invention
of "A MARINE ALARUM CHRONOMETER FOR ASCERTAINING THE TIME OF A SHIP'S
LOG LINE RUNNING OUT, THE TIME OF THE WATCHES ON SHIPBOARD, AND MANY OTHER
USEFUL PURPOSES;" in which said Letters Patent there is contained a proviso
obliging me, the said John De Lafons, by an instrument in writing under my
hand and seal; particularly to describe and ascertain the nature of my said
Invention, and in what manner the same is to be performed, and to cause the

page_text: same to be inrolled in His Majesty's High Court of Chancery within one
calendar month next and immediately after the date of the said recited Letters
Patent, as in and by the same Letters Patent, relation being thereunto had,
will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John De Lafons, do hereby describe and ascertain the nature of my said
Invention, and the manner in which the same is to be performed, by the several
Drawings in the margin of these Presents, and as follows, that is to say:
I construct and make the said marine alarum chronometer for ascertaining
the time of a ship's log line running out, which is a substitute for the half and
quarter minute glasses used at sea (and which may be called or denominated
log chronometer), as follows; and which, by various additions and alterations,
as after mentioned, may be made applicable to many useful purposes :-
EL
In Figure 1 and 2 in the said Drawings, the great wheel A has four pins
or ratchet teeth fastened at a convenient distance from the centre, or,
according to the use) a ratchet may be fixed with any number of teeth. B, the
arbor which passes through the plates, and carries the hand or handle, having
the end or some part of this arbor or work affixed thereto, propelled forward
by the main spring in the barrel C (or otherwise as hereafter mentioned);
this arbor has likewise the collet and piece D fastened to it, on which is put
the spring and click E and F, this click having a tail or pin at the end G,
which, passing by the pin or arch K, is drawn out of the ratchet. This click
and discharge may be made different ways, as diagonally, in Figure 3, in which
Figure the piece K is flat and parallel to the great wheel, or with a spring
only, as shewn in Figure 4, to act in the ratchet teeth and discharge the
arbor B (Figure 1 and 2). The click being drawn out of the ratchet by the
going of the piece, gives liberty to the arbor B to turn on the centres, and
the hand or handle, or any piece affixed to the arbor, to strike against a bell
or anything else at pleasure. This hand or handle, or other piece affixed to
the arbor, besides striking the bell likewise strikes the end or some inclined
plane aflixed to the pump piece 1, as the nutt L or otherwise, which being
struck by the hand, handle, or other piece as aforesaid, raises the pump piece 1,
and a pin affixed to it internally stops the machine by touching the escapement
wheel or balance. When the bell is not used this falling of the hand, handle,
or other piece as aforesaid, is sufficient notice of the expiration of the time
required. The picce thus stopped will remain so, when the hand or handle is
turned to the quarter or half minute or other time, until the nut L is pressed
down, which discharges the pin out of the escape wheel, or otherwise, at the
exact moment when required. A spring bears against the pump piece to keep

page_text: it in its place when either up or down. The great wheel A, designed for
nautical purposes, turns a pinion with a crown or balance wheel, which acts
in a common verge and balance, with fans or flys to adjust it accurately to
time (although any other escapement or pendulum.spring may be occasionally
applied, either to those for sea use or for other purposes. I also make the
machines with a rack or portion of a wheel, as.at Figure 5, which, when it
has acted on the pinion, will drop off by the power of the main spring, and the
rack itself, or any piece affixed thereto or to the arbor thereof, will, strike
against a bell or anything else at pleasure. There is a hand or handle upon
the arbor of this rack to turn to the required time as before mentioned. When
this construction is used there is a hole drilled through the pinion, and a
ratchet or pin affixed on the wheel, and a click.is affixed on this pinion, so
that the pinion may turn one way and lay hold of the wheel the other way; or
the pinion and arbor may be fastened together, and the. wheel be at liberty to
move one way and hold the other. This rack may also, when. it has done the
work in one pinion for the going or time past, drop into another for the
purpose of ringing a bell, as is.usual to alarums. When Figure 5 is used a
collar or rim should be affixed on the blank of the rack, of the same size as
the bottom of the teeth, but affixed on the blank space between the teeth,
which collar or rims falls into an arch or pins affixed on the pinion, and thereby
keeps the pinion in its place to receive the rack when wanted. The nautical
machine may also be made with an escapement and discharge, as at Figure 6.
The letters corresponding with Figs. 1 and 2 renders the first description
sufficient. The mechanism may be placed in a frame, like watch or clockwork,
or supported by cocks on one plate, at discretion. The pinion M, Figure 5,
to give motion to a train, or otherwise to ring a bell, as is usual to alarums;
or if a portion of a wheel be affixed to the arbor B, instoad of the hammer, as
at Figures 1 and 2, and fall on a pinion, as at Figure 5, the effect will be the
The great wheel A in Figures 1 and 2, or the rack in Figure 5, may
have the teeth contrate, which will bring the balance in another position, but
in other respects produce the same effect.
same.
When these machines are wanted for other purposes, such as regulating the
time of the watches kept at sea, or to awake any one at a given time, or for
regulating the time for culinary uses, such as boiling eggs or otherwise,
then the great wheel A, Figure 1 and 2, may turn any number of wheels
(instead of the scape wheel only) to multiply the time of the machine going;
those I make for pocket alarums go twelve hours; those for culinary uses
shorter spaces of time, according to the purpose to which they are intended to
be applied. The numbers for the teeth of the wheels and pinions are

page_text: calculated the same as watchwork. Where much accuracy is not required, I
substitute a train of wheels, and a fly or a skew wheel and worm; I also omit
the stop or pump work occasionally, and raise the hammer by a pin or tooth
affixed to the ratchet or arbor of the great wheel, as the hammer of a clock is
usually raised. These machines may be easily made by means of a weight
instead of the main spring, with all the above properties, except they are not
so properly portable, nor can they act in all positions. The power may also
be given to the said machines by a spring similar to a gun spring, either
double or strait or otherwise. The machines may be made of various metals,
hard wood, ivory, bone, or similar substances, whichever may be thought most
proper; but I prefer metal. In order to render the nautical machines
impervious to the water, they are screwed in and variously fixed with oiled
leather, bladder, or otherwise, and have a wooden or metal cap within a wooden
or metal box, with a handle for convenient holding, but may be made in
various forms to the same effect; they may also be easily made to pull by
a chain or string, or to push in a manner similar to a repeating watch. The
face of these machines should be divided according to the use they are intended
to be applied to, and are set by turning the hand or handle to the time required
to be known or determined.
In witness whereof, I, the said John De Lafons, have hereunto set my
hand and seal, the Fourteenth day of December, in the forty-sixth year
of the reign of our Sovereign Lord George the Third, and in the year
of our Lord One thousand eight hundred and five.