IMPROVEMENTS IN THE CONSTRUCTION OF COMPASSES AND APPARATUS FOR ASCERTAINING AND REGISTERING THE VELOCITY OF SHIPS OR VESSELS THROUGH THE WATER
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Jonn
RANSOM ST. JOHN, of the City of New York, in the United States of America;
Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent, under the Great Seal of Great Britain, bearing date
at Westminster, the Twenty-seventh day of December, in the fourteenth year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Ransom St. John, Her especial licence, full power, sole
privilege and authority that I, the said John Ransom St. John, my exors,
admiors, and assigns, and such others as I, the said John Ransom St. John,
my exors, adññiors, and assigns, should at any time agree with, and no others,
from time to time and at all times during the term of years therein men-
tioned, should and lawfully might make, use, exercise, and vend, within
England, Wales, the Town of Berwick-upon-Tweed, and in all Her Majesty's
Colonies and Plantations abroad, and in the Islands of Jersey, Guernsey,
Alderney, Sark, and Man, my Invention of "IMPROVEMENTS IN THE CONSTRUCTION
OF COMPASSES AND APPARATUS FOR ASCERTAINING AND REGISTERING THE VELOCITY
OF SHIPS OR VESSELS THROUGH THE WATER;" in which said Letters Patent is con-
tained a proviso, obliging me, the said John Ransom St. John, 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 same to be inrolled in Her Majesty's High Court of Chancery
within six calender months next and immediately after the date of the said
in part recited Letters Patent, as in and by the same, reference being there-
unto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
John Ransom St. John, do hereby declare that the nature of my said Invention
and the manner in which the same is to be performed, is particularly described
and ascertained in and by the following description thereof, reference being
bad to the Drawings hereunto annexed, and to the letters and figures marked
thereon (that is to say) :-
:-
My Invention of improvements in the construction of compasses and appa-
ratus for ascertaining and registering the velocity of ships or vessels through
the water, relates,―
First, to improvements in the construction of the mariners' or other
magnetic compasses, whereby any variation or deflection of the magnetic
needle from the magnetic meridian, if produced by local causes, may be at
once seen and the amount of such variation or deflection indicated and
ascertained by merely inspecting the card.
The second part of my improvements relates to certain novel constructions
or arrangements of apparatus for ascertaining and indicating the rate or speed
of ships or vessels.
In the accompanying Drawings I have shewn two different kinds of appa-
ratus for effecting the above purpose; the first of these I denominate an
"aquatic velocimeter," and which consists of an apparatus which is to be let
down into the water under the vessel, through a hole made in the bottoni
thereof, on one side of the keel. This apparatus consists principally of a fan-
wheel which is caused to rotate by the water passing by it, and, by means of
gearing, to communicate motion to hands or indexes adapted to a graduated
dial plate in the cabin or on the deck, so that by an inspection of the dial plate
not only the total distance run can be clearly seen, but also the speed or rate at
which the vessel is then proceeding can be accurately ascertained. Under
this head I have also described an improved geared hand log, whereby I am
enabled to ascertain and register in a more accurate manner than with the
ordinary log, the length of line run out in a given time and consequently the
rate of speed of the vessel.
Having thus briefly set forth the object of my several improvements, I will
now proceed to describe in detail. the arrangements and construction of parts
which I have found by experiment to act most satisfactorily for effecting the
intended purposes.
In reference to the mariners' compasses to which the first improvement
relates, I would observe, that it is well known that the magnetic needles of
mariners' compasses are liable to be acted upon by local causes so as to cause
them to vary from the magnetic meridian, and thereby indicate erroneously, which,

page_text: if not known at the time, may cause the master of a vessel (if trusting to his com-
pass and believing it to act correctly) to steer in a wrong direction, and perhaps
unwittingly run into danger. Now the object of this part of my improvements
is to indicate when any variation of the magnetic needle of the compass takes
place from local causes, and to determine on inspection the amount of such
variation or deflection, so that by a simple calculation, the master can easily
ascertain the true magnetic meridian. Such being the nature and object of
my improvements in compasses, I denominate compasses constructed upon my
improved plan "self-determining local variation compasses."
The following is a full, clear, and exact description of the construction,
preparation, operation, and effect of the said discovery and improvements,
reference being had to the Drawings annexed to and making part of this my
Specification of the said discovery and improvements, wherein Fig. 1 is a plan,
and Fig. 2 is a sectional elevation, of a compass fitted with my improvements.
The like letters and numbers as marks of reference apply to the same parts in
each Figure, as follows:-1 is the spindle or pin (see Fig. 2) to carry the cap 2,
which sustains the ordinary compass card 3, and the main magnetic needle a,
shewn by dotted lines in Fig. 1 as under the card; these are so far made as usual;
but between the cap 2 and needle a a cross bar b, shewn by dotted lines in
Fig. 1, is fitted under the common card, or may be made to carry a circle of
thin metal, on which the usual divisions of the compass may be marked; but
in either case the ends of the bar bare each fitted with a pin or spindle c or
c¹ that sustains a cap dor d', each cap carrying an index arm for f¹, the
shorter ends of each of these have a balance weight 4 to keep the arms
horizontal, and the ends of the bar 6 are each fitted with a forked shield or
keeper-piece 5, one tongue of which is secured beneath the bar b, the other
tongue turns inwards and over the caps d or d¹ so as to keep them and the
index arms for f¹ upon the pins c or c¹. Beneath these caps and arms are
fitted the auxiliary or satellite magnetic needles and e¹. On the card, or on
two metal arms attached to or made with the bar b, if a frame. is used instead
of a card as before noticed, are two graduated sectors g, g, for use as hereafter
set forth; this completes the general construction and description of the com-
pass proper. The box in which it is placed is shewn in the usual form, but
may be fitted in any other convenient manner; the preparation of the needles
and the adjustment of the other parts, being as follows:-The main needle a
is to be properly and evenly hardened at each end, and is to have these as
equally charged as possible, by giving each the needful number of touches
with the proper poles of the inductive magnet, and the position of the magnetic
needle a under the card or frame, in relation to the cardinal points, is to be

page_text: the same as now usual; and the best of even grained steel is to be used in
making both needles and satellites.
The auxiliary or what are herein termed the satellite needles are to be
placed, as shewn in the Drawing, with their centres as nearly as possible
equidistant from the main centre and the centres of the poles of the main
needle. They are to be about one-fifth of the length of the main needle, they
are to be about one-thirtieth part of the weight of the main needle, and are
to be hardened and charged at the ends by the inductive magnet precisely in
the same manner as the main needle. The satellite needles and index arnis
f and with the caps d and d' are to be properly balanced in place on the
pins c, c', before these needles are charged by the inductive magnet. For
adjusting the magnetizing of the satellite needles the main when duly charged
must be laid and kept in the magnetic meridian until the satellites are
charged, and this is to be done by touching them with the proper poles of
the inductive magnet a sufficient number of times to make them stand
parallel with the main needle with the north pole of each satellite needle,
toward the south pole of the main needle, and vice versâ, and to make them
work true the charge must be increased or diminished as the progress of the
operation may shew them to be needful. If, for instance, the north pole of
either satellite be too weak it must be touched by the south pole of the
inductive magnet; if after that it be too strong the south pole of the satellite
must be touched with the north pole of the inductive magnet. If both poles
become too strong for the proper effect above described, either may be
weakened by touching it with tho similar pole of the inductive magnet. To
avoid this, the first charge of the satellites should be quite weak to admit of
strengthening up to the point of equal relation to a position with the main
needle and the nonius, and care should be taken not to give the satellites
a maximum charge at first. This process requires great care, attention, and
patience, and should not be hurried, as it is not possible to foretell the
number of touches needful because there is no means to measure the amount
of susceptibility to the influence of the main needle which the first touch of
the inductive magnet may give to the satellite, nor can the increase or
diminution of this susceptibility by any subsequent touch be foreknown, there-
fore the process must be patiently followed up until the satellites stand parallel
to the main needle when the index arms f and f¹, standing at right angles
to the satellites, will be in the same line or in the equator of the compass
card or frame at the point marked o, which is the nonius of each sector
scale 9, and is the point of no variation of the main needle a.
The satellites being thus equally charged and adjusted, the sector scales g

page_text: are then to be graduated as follows:-The line of the scale being marked on
the card or frame from the pins c, c¹, as centres, at the northern extremity of
the sector scale line on the east side place the letter E, and on the southern
extremity the letter W, at the northern extremity of the sector scale on the
west side place "W," and at the other end "E." With the nonius o in the
equator of the card, and under the points of the index arms f, f¹ move
the main needle one degree either east or west of the true meridian and let
it lie there. When the satellites have settled perfectly still, make a point
mark on the line of the scale under the point of each index arm; this done,
move the main needle ono degree over and past the magnetic meridian the
other way, and when the satellites have become perfectly still mark under
the index arms as in the first case; proceed thus alternately until the scales
are marked each way as high as the satillites will work before they turn back
or stand still, when the main needle is moved forward either way, which will
depend entirely on the susceptibility of the needles, for which reason it will
be almost impossible to make two sector scales aliko for different needles, and
rarely or never beyond ninety degrees, though a full circuit of the satellites
may be made by adjusting them with a light charge or at a sufficient distance
to have their poles reversed from the above process or pointing in the same
direction as the poles of the main needle.
By the first described arrangement and charging of the satellites, when the
main needle passes ninety degrees from the magnetic north either way, the
satellites and index arms will begin to return upon their scales as the main
needle continues to vary, and leave the magnetic meridian beyond ninety
degrees, but they will both stand at nonius o when north pole of the needle is
made to point due magnetic south, and from thence up to ninety degrees on
the main needle returning, the satellites with the index arms will proceed
upon the sector scales, and from ninety to due magnetic north they will
gradually return to nonius o when the main needle arrives in the magnetic.
meridian.
It will be understood by the foregoing description of the construction of the
compass, and the preparation and adjustments of the satellites and sectors,
that the marks "E" indicate easterly variations, and the marks "W" indicate
westerly variations, according to the direction the arms f. f, tend to form
their respective noniuses, and the amount of this variation either way under
all ordinary causes with usual protection to the compass will be ascertained!
as follows:-When there is no variation from local causes. the index arms;
will each be over its respective nonius o; but when the satellites vary, so
that each index arm points to any given number of degrees on its sector scalo

page_text: add the two amounts together, and the half of this sum will be the amount
of the actual variation either east or west produced by local causes, the
direction of the variation whether east or west being indicated by the letters
that the pointers may both tend towards from the nonius; but if both
indexes shall be either north or south of the equator or nonius, between the
east and west points of the sectors, subtract the less from the greater angle,
and the balance will be the variation of the main needle from the magnetic
meridian in the direction shewn by the greater angle; but such a circum-
stance will at once inevitably indicate the existence of some unusual or
extraordinary disturbing cause in the vicinity of the compass either at the
north or south side, whichever the pointer may incline to.
Having tried one satellite needle in every position round the compass, and
having also tried as many as seven satellites in all possible positions, I decide
on using two acting in the line of the equator, and with their centres as nearly
as possible equidistant from the centres of the poles of the main needle, as the
most effective, and perhaps the only mode fitted to meet all contingencies, so
that while they will generally indicate all ordinary variations of the main
needle, they will also indicate and enable the mariner and surveyor to know
or detect the presence and action of any unusual and extraordinary disturbing
causes in the vicinity of the compass in every situation or service in which the
instrument is needed or can be used; these being the effects produced by my
herein-described discovery, Invention, and improvements, and the mode of
constructing, preparing, and arranging the same.
I do not claim as of my Invention the various parts of mariners' or
surveyors' compasses, which have been before known and in use; and I would
observe, that my improvements can in most instances be added to compasses
already in use. But I do claim as new and of my own discovery or Invention,
and therefore desire to secure by Letters Patent, the application of satellites
or auxiliary needles to the magnetic compass, such needles being prepared,
applied, and adjusted in the manner and for the purposes as herein set forth,
including any merely mechanical variations that shall be actual equivalents of
the means employed, and substantially the same as applied by me for the
purposes herein set forth.
The improved "aquatic velocimeter," which forms part of the second head
of my improvements is shewn in Sheet II. The mechanical arrangements of
the instrument are such, that it comprises the following advantages:-First, the
means of fixing the mechanism in its proper place for use, and detaching the
same at will for examination or repair, and refixing it again for use, without
reference to the then situation of the ship; second, denoting and registering

page_text: with accuracy the number of miles or knots the ship has run through the
water; thirdly, the means of so detaching the working parts from the register
at will, that the latter shall not operate when the ship is at anchor in a tide-
way; fourthly, the fitting the acting parts, so that they are protected from the
effects of any vertical motion either by the ship or the water.
Fig. 3, in Sheet II. of the Drawings, represents an elevation of the velo-
cimeter wheel, and a section of the pipe enclosing the connection to the
recording clockwork, the registering face of which is also shewn in this Figure;
Fig. 4 is a section of the clock work, and a side elevation of the velocimeter
wheel; in these two Figures is also shewn the connection from the velocimeter
wheel to the clockwork; Fig. 5 is a front elevation of the clockwork, with
the recording face removed; Fig. 6 is a plan of the pipe and parts near the
velocimeter wheel. The same letters and other marks of reference apply to
the same parts in all the Figures, and the parts are all drawn and shewn to a
scale of about one-third of what I believe will be found the most convenient
size in use. A is a pipe or tube (of any suitable metal) commencing from
the deck, or from any convenient point above the water line in a perpendi-
cular position in the ship and prolonged downwards, so as to terminate with a
water-tight joint on the outside of the ship's bottom and in the inside of the
orifice; the pipe A is fitted with a strong bead or flange 1 that serves as a
seat for a metal circular plate a, which prevents any indirect current of water
into or from the tube A; and above it is an upper frame b, b, the sides of
which have grooves 2, 2, Fig. 4, that receive ribs 3, Fig. 3, on each side in
the whole length of the tube or pipe A; these ribs and grooves are set fore and
aft of the ship, and guide the apparatus into or out of the proper place for work,
the cross piece 4 of the frames 6 having a rope, rod, or chain 5 by which the
whole frame is to be lowered or raised at will. Below the orifice the plate a
has two hanging standards c, c, and a foot piece c', these and the frames b
above are all to be made solid with the plate a. Between the standards c, c,
two screw centres 6, 6, carry the ends of the principal shaft or arbor d, on
which are set eight paddle blades B, these are placed on the shaft d, not
parallel with the axis, but at such an angle of deflexion in proportion to their
length that a progress of about three feet in a direct line through the water,
shall give the blades B exactly one complete rotation, and no more.
At e, c,
two flanges cast solid, with one of the standards c form the top and bottom of a
box which is enclosed with a strip of metal screwed on the sides of the
standards, and has a hole to pass the shaft d of the fan wheel.
On the shaft d and within the box is fitted a single-thread worm wheel 7,
that gears into a corresponding horizontal tooth wheel f, Figure 4, with forty

page_text: teeth, and set on a pivot stepped arbor 8 on the bottom of the box. The top
of the spindle of this wheel f is made square at 9, and takes into a socket in
the lower end of a short vertical arbor 10, as shewn by dotted lines in Fig. 4;
the arbor 10 passes through the top of the box e and through the plate a of
the frame, beneath which a set collar 9 and pin 11 keeps the shaft 10 from
rising off the spindle of the wheel f. Above the plate a the arbor 10 has a
pin 12 that takes into a slot in a socket h at the lower end of a vertical tube i;
this is prolonged up through the tube A, and finishes at the top with a square
key socket 18, which receives the square end of a short arbor k, set in a frame
14, 14, which is fixed in the lower part of the clockwork case C. The arbor
k carries the leading pinion of twelve teeth, and this gears into a leading
wheel m of sixty-six teeth, set on a spindle 15, which passes through the
upper frame plate 14 and finishes with a short square, having a round end
above it; these parts receive the socket piece 16 of the coupling rod n, which
is fitted to the top of the spindle 15, so that the coupling rod n may be just
lifted and turned to set the register hands above and yet not to be entirely
detached off the spindle 15. The top of the rod n is formed as a socket, so
that the lower end of the first clockwork arbor p may be attached or detached
at pleasure. Above this the back plate 7 of the clock frame is lengthened
down with two bracket pieces 18, through which the rod p passes, receiving
on its top the bevilled runner pinion of ten teeth, fitted to gear into the
bevelled wheels; this has sixty teetli, and is set on an arbor 19 which
bears against the plate 7 and carries the next pinion and the canon pinion
and the tubes between that and the face, and outside the face it also carries
the hand 21; this hand counts rods, yards, or any other unit of measurement.
Next the wheels a pinion of eight teeth is made with the arbor 19, and gears
into the wheel t of eighty teeth, fixed on an arbor 27 above, and carrying on
the same arbor a pinion of eight teeth that gears into a wheel v of eighty teeth
on the canon arbor; this arbor passes through the clock face and terminates
just within the point of the arbor 19 and carries the hand 22, which counts
miles up to one hundred in number; this canon arbor is fitted with a pinion
of sixteen teeth that gears into a wheel w of eighty teeth; this wheel rotates
freely on the arbor 27, with a nave a, that is formed as a piuion of thirty
teeth, which gears into a wheel u of sixty teeth; this is set on the second canon
arbor, which goes through the face just short of the first canon arbor, and
carries the hand 28, which counts miles up to one thousand. y is the dial
plate and three sets of divisions; 2 is the frame, which carries the glass 24;
over the dial and at 25 an opening and door is shewn, by which the fingers
can be introduced to reach the socket 16, to set the hands in unity at the time

page_text: the ship is taking a departure, and thereby avoid removing the glass and
frame z, and yet set the hands in unity without touching them. The parts are
shewn as in a vertical metal box placed on a pedestal, but the whole may be
placed on or in a box or frame of wood or metal, as taste or convenience may
dictate.
To make a water-tight joint at the bottom of the vessel, the lower part of
the tube A may be made separate from the continuous part above, in the
manner shewn in Fig. 7, which is a section at a right angle to Fig. 3, and
shews a pipe with a flange 26 below the outside planking of the ship, and the
pipe A coming above the inside planking, where a screw thread is cut on it to
take a union nut 28, the lower part of which has an external flange to take
the inner planking, and the upper part an internal flange to overlie the screwed
part of the pipe, taking a flange turned outward on the lower end of the next
upper length of pipe between the inner flange of the nut 28 and the top of the
screwed part, so that the outer flange 26 is held firmly against the outer
plank, and the two lengths of pipe A are held firmly together by the same
connexion or union screw.
In this Figure the rib 3 is shewn as only in that part of the pipe that goes
through the bottom of the ship, and is shewn as tapered at the top to pass and
receive the grooves 2, 2, in the sides of the frames 6, b, without the necessity
of having ribs in the upper part of the tube, as the frame when lowered by a
rod or bar can be directed to place the grooves over the tapered tops of the
ribs, which entering the grooves in the descent at once seats the mechanism in
place for use.
The operation and turning of the parts and the proportions of the gearing
being stated, it will be seen that the paddle blades B being set at a proper
angle with the axis on which they rotate, that the motion of the vessel through
the water, will cause the blades B to move round, and by means of the worm 7
operating through the wheel f, pinions I, leading wheel m, runuer pinion », and
wheels cause the arbor 19 and hand 21 to move and indicate the vessel has
run. This hand indicates units, but by the additional gearing above described,
the other hands are made to indicate hundruds and thousands of miles, or any
other geographical measurement according to the arrangement of the gearing,
which may be altered to suit circumstances, as, for instance, to measure
metres and kilometres for marine leagues for foreign vessels. It will be under-
stood that the distance run in a given time will be ascertained by comparing
the hands on the dial with a clock or watch, thus practically giving the rate
of the ship in miles per hour by mere inspection.
. It is well known that many attempts have been made to apply. machinery

page_text: for the purpose of ascertaining the rate of speed at which a ship has moved
through the water in a given time, and it is believed, the best which is known
is Massey's log; this, so far as known, is a box containing machinery, which
is towed through the water by the ship, and is liable to uncertainties, because
a fast ship in a short sea will frequently jerk it out of the water, when it will
become inoperative; the motion of the water and of the ship is always changing
the angle of the tow line, and on hauling it on board, it is also liable to injury
by striking the vessel when pitching heavily. Another log has been made,
fitted to be placed under the counter of the ship, where it is in the eddy water
the ship draws after her and becomes uncertain in its rotation beside being
open to all the former objections when hauling into or out of place for use;
and others have been contrived in various ways, but I do not know of any
mechanical apparatus for ships' use that is so placed beneath the bottom of
the ship as to be clear of all ordinary accidental interferance, by fitting the
vanes or paddle blades B into a frame constructed with grooves to slide on
ribs in a tube or pipe, the bottom of which supports the frame by a bead or
flange surrounding a disc a that cuts off or prevents the effects of any vertical
motion of either the ship or the water on the paddle blades B to destroy the
accuracy of the instrument, so that the working parts of the log or velocimeter
can be withdrawn for any needful purpose, and again replaced for use; nor
do I know of any similar instrument for these purposes that is made to
operate as a standing register of the whole distance a ship bas actually run
without a direct reference to time during any portion of the distance, by the
operation of the vanes or blades B, through a rod in the tube A, upon a
registering set of clockwork wheels and hands, which the herein description
and Drawings shew as registering yards, or rods, and miles to one hundred,
and thence to one thousand; so that, by increasing the number of wheels and
pinions, the registry may be made to any desired extent. I do not mean to
limit myself either to the stated extent of the numerical registry, or to-the
sizes and proportions of the parts and gearings, but to vary these as may be
needed, nor do I mean to be limited to the mode shewn of fitting the moving
parts, but to add any mechanical means for lessening friction and wear, when-
ever and wherever practical use may.evince the propriety of so doing.
Having thus described this part of my Invention, and set forth the means I
employ, and the differences between my improvements and those that have
been heretofore known, I do not intend to claim separately, any of the parts
herein described, as most of them are well known, and in common use for
other purposes; but what I do claim as new, and of my own Invention, and
desire-to secure by Letters Patent, is the attaching the discs or plates a 'to

page_text: the sliding frames b and c, which frame c carries the shaft d of the paddle
blades B, when the said frames and plates are fitted to be lowered into or
raised out of a tube A, in such a manner that when in place for use the plate
a may prevent any indirect current of water from ascending into or descending
out of the tube A, and thus disturb or destroy the accuracy of the instrument,
the paddle blades B, by my improvement, being subject only to the direct
action of the vessel's progress through the water, as described and shewn.
My improved geared hand log, which forms the second improvement in this
part of my Invention is shewn in the several Figures in Sheet III. of the
the accompanying Drawings.
This part of my improvements relates to a novel combination of mechanical
movements with the common log keel, and the attachment to the log line of a
mechanical substitute for the common log ship or piece of wood at the end of
the line. These improvements on the common log register, the length of log
line run out in any given time, so as to ascertain the rate of speed in a more
common manner by the application and combination of mechanical means not
before employed together for such purposes; and in Sheet III. of the Drawings,
Fig. 8 is a plan view, and Fig. 9 an elevation partly open; Fig. 10 is a
section through the line A, B, of Figures 8 and 9; Fig. 12 is a plan of Fig.
10, with the dial plate and glass removed, to shew the internal positions of the
operative parts under the dial plate. These four Figures are all drawn at about
the half real size of the instrument, with the parts employed as in place for
use. Fig. 18 is a sectional elevation of the substitute adopted by me for the
piece of wood usually known as "the log ship," and is similar in form to a
small parachute or strong parasol; but will be herein designated by the
nautical term of the log ship to identify it with the use to which it is applied
by me, and is in this Fig. 13 shewn as if in operation. Fig. 14 shews the
same as Fig. 18, but with the becket ferrule on the long staff detached as
described hereafter and the log ship folded, as while being drawn on board after
use. In these two Figures 13 and 14, the log ship is shewn as about one-
sixth of the proper size for use. The detached Figures are separately referred
to, and the same letters and numbers as marks of reference apply to the like
parts in all the several Figures.
In these C is the main frame of metal, with one handle D and a second
handle E; these handles are shewn as secured on the frame, but may be cast or
made solid with the frame. On the upper and outer corner of the handle E
is a pivot 1, carrying a twelve-second log glass F, made in the usual manner.
a is a shaft, sustained by centre screws 2, 2, going through the frame sides
and entering sockets in the ends, so that any looseness or any unusual strain

page_text: shall not disengage the shaft a from its place. This mode of mounting the
reel shaft is shewn sectionally in Fig. 17. x, x, are two flanches, cast solid
with the shaft a, and turned and fitted to receive the heads b, b; these have
between them trundle staves 3, 3, and collectively form the reel G for the log
line 4. At 6, 6, two pieces, to form the top and bottom of a box H, are cast
or made with one side of the frame C, between that and the log reel, and
enclosed with a strip of metal screwed at the ends, with on opening to pass
the shaft a within this box H; this end of the shaft a is formed as a worm-
wheel c, which gears into a wheel & having fifty-five teeth, and set on an
arbor 5, the foot of which steps in a pivot; the upper end is prolonged through
the top 6 of the box H, so as to terminate as a squared top inside the index or
dial box I, which is secured by screws on the top of the box H. The squared
top of the arbor 5 receives the first pinion wheel e, the teeth of which are
bevelled outwards and downwards, and within the teeth the under side is
formed as a collar that lies into a countersink in the head of the governing
lever g; this has an eye to lie round the arbor 5, and a fulcrum 11 in the
side of the box I. Between the arbor 5 and fulcrum 11 a keeper spring h
overlies the lever g and keeps that down and the pinion e at the lowest point
on the arbor 5, except when the outer scale-formed end 12 of the lever g is
depressed, as hereafter described. Within the box I a pivot steps in the
centre takes the lower end of. the arbor 7 that carries the counter wheel f;
this is made with teeth bevelling outwards and upwards to gear fair with the
teeth in the pinion e when that is raised on the arbor 5 by depressing the
outer end of the lever g. The top of the arbor 7 is drilled into to receive a
button-topped pin coming down through the glass 13; this sets the index
point or hand 9 which overlies the index card 10, the divisions on which will
be explained hereafter. On the top of the box I is a cover or hood i, having
a hinge on which it swings to open or shut, and a common button latch 14 to
keep it shut when not in use. In the Figures 13 and 14, representing the
substitute log ship, p is the top of a hollow tube or handle k, with a circular
set of fixed points 15 taking the top ends of the stretcher pieces 1; these are
connected by stretcher pieces 16 to the joints 17 of the sliding tube m, which
slides loosely on the hollow tube. The short staff or handle & is formed with
the lower end of the part p, and round this is a tube n, that slides on the
staff and enters the lower end of the tube m between that and the handle
tube k at the point 18, and is made slightly conical to hold well between the
tubes m and k, like a circular wedge, yet start easy by a jerk, and having two
eyes 19, to which the two ends of a piece of log line o are attached, and at the
bight 20 the outer end of the log line 4 is attached, as also one end of the

page_text: stray and draw home line 21; the other end of this is attached through an
eye 22 to the prolongation p of the tube : above the joints 15. 2, 9, are the
external edges of the covering on the stretchers 7, 7, which covering may be
made of thick sheeting linen, or light sail duck, or any suitable material, and
varnished. At ris a small portion of lead, sewed into the inside near or on
one end of the stretchers 7, and exactly opposite at s a portion of cork is
attached.
The parts acting with the leg line are shewn sectionally and separately, and
on an enlarged scale in the detached Figures 15 and 16, and connected
together for use in the collective sectional Figure 13. Except the spring
hand frame and log reel, all the metal parts should be made of brass, as this is
the stiffest and strongest metal in proportion to weight, and is not speedily
corroded and destroyed by the action of salt water. When thus prepared
and adjusted, the instrument is to be used in the following manner:-
It is intended that one man shall hold the reel in both hands, so that the
right thumb shall readily press on the scale piece on the end of the lever g,
the log glass F being in the situation shewn by dotted lines in Fig. 9, the
pivot 1 sustaining it outside the handle E, directly over the forefinger of the
man who sees that the index pointer 9 is at o, and the sand all in the bottom
of the log glass; the conical tube n is pushed in between the tubes k and m,
so as to hold all the parts expanded, as in Fig. 18, before throwing, and a
second man throws the log ship with a sufficiency of stray line to reach the
water, and allow the motion of the vessel to draw the log line taut, when the
log ship will take the proper position in the water; the man holding the reel
now instantly turns the log glass F over with his forefinger, so that it takes
the position shewn in Fig. 9 by the full lines, and at the same instant presses
down the scale 12 and outer end of the lover g by pressing on the top of the
long glass, raising the inner end of the lever, and thereby putting the pinion e
into gear with the counter wheel f. The log line 4, running off and rotating
the reels, puts all the parts in motion, and the lognian, keeping all steady
watches the log glass until the sand has run out, then instantly turns the glass
with his forefinger, the keeper spring instantly depresses the lever g₁ and
takes the pinion e down and out of gear with the counter wheel f, which stops
directly, leaving the index pointer 9 at the point it had reached on the index
card 10 at the time the sand in the log glass had run out, and denoting the
rate per hour, in miles and fractions, at which the ship or vessel has moved
through the water during the twelve seconds occupied by the sand running in
the log glass. The second man now "hauls home" on the log line; this jerks
the tube w from between the tubes and m, and off the handle k, leaving the

page_text: log ship K. to turn end for end, and at liberty to fold together, as it is shewn
in Fig. 14 with the stay line 21, taking the connection to the log line 4, by
which it is drawn on board the vessel as the line is wound on to the reel, as
usually practised.
The common hand log, as heretofore used, consists only in the log reel and
line in the frame, the outer end of the line being attached to three short
pieces usually called the becket or crowfoot of the line; two of these parts
are permanently attached to a three-cornered or segmental-formed piece of
thin wood, usually termed the log ship, that has a small piece of lead attached
to one edge, just enough to make the log ship float edgewise in the water,
with one edge flush with the surface. The third part of the becket or crow-
foot is usually attached to a peg stuck into the lower angles or curve of the
log ship, so that, when overboard, the log ship and line are at right angles to
each other. This, when thrown overboard, runs the log line off the wheel
but admits of lateral escape of the water, partly by the flatness of the surface
and partly by the smallness of the size, so that the log ship is not so stationary
in the water, but that it follows the ship in a more or less degree until the
line is pulled "home;" this disengages the peg at the lower angle, and throws
the log ship flat on the surface of the water by the fixed parts of the becket
near the upper edge, when it is easily hauled on board the vessel. The length
of line run out after the stray line is gone in a given number of seconds, as
marked by knots in the log line and timed by a sand glass, is usually assumed
as a data to ascertain the rate of the vessel through the water, but these
modes are liable to uncertainty and error from miscounting the number of
knots run out and not accurately allowing for the stray line at the commence-
ment, but most importantly from not starting to count or stopping the log line
and turning or noting the last sand of the log glass at the same instant of
time when either beginning or ending, or both, so that the actual rate of the
vessel is very rarely even approximated to by these means.
With the gearing attached as herein shewn and described between the log
reel and the index and glass, the length of the stray line at the commencing or
ending the operation is of no consequence, as, if the lever g is depressed at
the same instant the glass F is turned, the log ship having hold in the water
runs off a given length of line in the twelve seconds, and the lever being set
free by the log man at the instant the sand has run down, the length of log
line run off in the time, moving the gearing as it runs off, gives the rate per
hour, independent of what line has run off before the glass is turned to
commence running the sand, and equally independent of what log line may
run out after the sand has run down, provided the log man lets go the lever g

page_text: as the last sand descends, as all the line that runs off the reel afterwards has
not any effect on the gearing and recording parts of the machine, so that these
beginning and ending their work with the run of the sand in the log glass
denotes the rate of the ship by mechanical means acting with mathematical
accuracy.
1
I not mean to confine or limit myself to the mode herein described and
shewn of arranging the gearing to a twelve-second log glass, but to vary both
the glass and the gearing, by calculating the gearing to fit the glass, whether
running a more or less number of seconds, so as to obtain the same result,
namely, a mathematical measure of a ship's speed through the water by the
application of similar mechanical means to the common log reel and line
already in use, and employed with a more mechanically effective log ship,
such as herein described, which has both a larger spread and deeper bold in
the water, with a concave face acting against the water, by which any lateral
escape of the water is very much lessened, if not entirely prevented, and the
log ship remains so nearly stationary while in use that the effect of the pull on
the line by the motion of the vessel does not cause any material error in
counting the rate of the vessel's speed. In case of accident to the mechanism,
the log wheel may still be used with a line marked in knots in the usual manner
either with the parachute or the common log now in use.
Most of the parts taken separately and described herein as used by me for
this purpose are well known and may have been applied to other uses, bat
I do not know of any Invention in which the application, arrangement, and
combination of these parts have been used to produce an instrument that
through mechanical means will denote with nearly mathematical certainty the
rate per hour at which a ship or vessel travels through the water during a
fixed, limited, and known time, I therefore claim as new and of my own.
Invention, and desire to secure
Letters Patent,-
First, the arrangement of the log glass F, lever g, pinion e, and wheel f,
whereby the motion given to the clock work by the reel G is communicated
to the index 9 during a definite period of time, the parts being so proportioned
and the dial so divided that the index moving while the sand is running in the
log glass F shews the rate of speed at which the vessel is moving per hour
of time during twelve seconds, or any other known time, the parts being
arranged and operated on substantially as described or in a manner equivalent
to produce the same results by the like means.
Second, the application of a parachute K to the purpose of a log ship, and
the combination therewith of the cylindrical wedge n or its equivalent to enter
between the tubes k and m to keep the log ship K spread when in the water

page_text: and disengaged when hauled in to "fetch home," so that the log ship closes
and turns end for end in the water, and is easily hauled on board; the said
log ship being used with the reel and registering parts herein described and
shewn or with any other means of supplying and determining the amount of
log line run out during a known period of time.
In witness whereof, I, the said John Ransom St. John, have hereunto
set my hand and seal, this Twenty-fourth day of June, in the year.
of our Lord One thousand eight hundred and fifty-one.