A MACHINE FOR MEASURING A SHIP'S WAY, WHICH WILL BE OF GREAT USE IN NAVIGATION
Year: 1772

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
Foxon, of Deptford, in the County of Kent, Carpenter, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Fifth day of December, in the thirteenth year of His reign,
give and grant unto me, the said William Foxon, His especial licence that I,
the said William Foxon, during the term of years therein expressed, should
and lawfully might make, use, exercise, and vend, within England, Dominion
of Wales, and Town of Berwick-upon-Tweed, my Invention of "A MACHINE
FOR MEASURING A SHIP'S WAY, WHICH WILL BE OF GREAT USE IN NAVIGATION;" in
which said Letters Patent is contained a proviso, obliging me, the said
William Foxon, under my hand and seal, to cause a particular description of
the nature of my said Invention, and how the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery, within four calendar
months after the date of the said recited Letters Patent, as in and by the
same (relation being thereunto had) may more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Foxon, do hereby declare that my said Invention of a Machine for

page_text: Measuring a Ship's Way, which will be of great Use in Navigation, is described
by the Drafts and explanations thereof following, viz*:-
The hydrometer consists of a spiral, log, of sufficient weight to be just
buoyant, which kept constantly in the water during a voyage will revolve with
a swiftness proportional to that of a ship; this is connected to a train of
wheelwork within board, by means of a line long enough to keep the log out
of the eddy of the ship, which is at a medium about fifteen fathom.
As the log revolves it tends to twist the line, which effect is immediately
communicated to the arbor (A), which carries an endless screw (B) and a
fly (C) to regulate its motion; and this is the first mover of the rest of the
wheelwork.
The screw (B), which takes into the wheel (D), which carries a pinion of (E),
takes into (F), carries an endless screw (G), takes into a wheel (H), carries an
endless screw (I), takes into a wheel (K).
A nautical mile, according to the latest and best experiments, contains
6084 feet, but in the machine it is estimated at 5998 feet, the difference
being thought necessary to be neglected to prevent the ship's overrunning her
reckoning, but which may be easily reduced to a proper standard by arith-
metical calculation, or such alteration in the train of the wheels as may be
thought expedient.
Now, as the log makes one revolution for every 2 feet 41% in. that the ship
moves thro' the water, consequently the wheel (D) makes one revolution in
49 feet 11 in., or one knot; therefore, in twelve such knots the wheel (F)
will make one revolution; and, as the axis thereof carries a hand round the
dial plate f, that plate will serve to shew the smaller distances to every 7th
or 10th part of a knot.
The wheel (H, as is evident, will be turned in 120 times 12, or 1440
knots, which is equal to 12 miles at the rate first assumed, 120 knots being
equal to 71977 feet; now this carries round a hand on the plate h which
shews to every tenth of a mile as far as 12 miles; but as a ship may go more
than 12 miles before it may be convenient to inspect the log, a third dial
plate K is contrived, whose hand being moved once round for every 24 turns of
the last,. will shew the ship's way as far as 288 miles with only one revolution
of this last-mentioned hand; and consequently, running on one course, it need
only to be inspected once in 24 hours.
For the better reducing the mile here assumed to the true nautical mile,
note, that 100 true miles are equal to 101 miles assumed.
To use this machine on a voyage, at the moment of beginning your reckoning,
write off in your log book the numbers standing on each plate, beginning with

page_text: that whose hand moves swiftest, viz., f, and the same repeated every 24 hours,
or oftener if the first course is changed during that time; the distance run
during the interval will be obtained by common substraction.
In witness whereof, I, the said William Foxon, have hereunto set my
hand and seal, this Seventeenth day of March, One thousand seven
hundred and seventy-three.
KUGELEY.
JAC BANNISTER.
AND BE IT REMEMBRED, that on the Twenty-fourth day of March, in
the year last above mentioned, the aforesaid William Foxon came before our
said Lord the King in His Chancery, and acknowledged the Specification of his
Invention aforesaid, and all and every thing therein contained and specified,
in form above said. And also the Specification aforesaid was stampt according
to the tenor of the Statute made in the sixth year of the reign of the late
King and Queen William and Mary of England, and so forth.
Inrolled the same Twenty-fourth day of March, in the year abovesd.