Improvements in Chronographic Apparatus.
Year: 1894

page_text: Date of Application, 5th Sept., 1894
Complete Specification Left. 24th May. 1895-Accepted, 20th July, 1895
PROVISIONAL SPECIFICATION.
Improvements in Chronographic Apparatus.
FREDERICK JOHN SMITH M.A. F.R.S. Trinity College Oxford, Clerk in
Holy Orders Millard Lecturer in Mechanics Trinity College Oxford, do hereby
declare the nature of this invention to be as follows:-
A. carriage furnished with three grooved wheels, runs on two parallel and nearly
horizontal rails, made of hard material. This carriage is propelled by means of a
spring, or by a falling weight which acts upon the mass of the carriage for a given
time and is then detached, I attach to the carriage a heavy fly wheel geared to
one or more of the grooved wheels on which it runs, this increases the uniformity
of its motion. The carriage is brought to rest by a projection attached to its
back running between two leather bands. The carriage carries a smooth surface
which may be smoked, this receives markings from electromagnetic styli and
tuning forks.
A pillar furnished with geometric slides carries the electromagnetic styli and
tuning fork, in front of the carriage.
The electromagnetic styli are so constructed that two sucessive markings_can
be obtained from one scribing point when two currents are sucessively broken,
I also use spiral springs of iron as cores for the electromagnetic styli. I read the
traces or markings on the smoked surface by means of a species of beam compass
furnished with two legs at right angles to the beam, each of which carries a lens
or small microscope for shewing the exact terminations of a tune trace, the legs
are adjusted by means of a screw with a divided head.
The object of my invention is to furnish a means for determining small periods
of time, such for example the time of flight of a projectile over a space of twenty feet.
The invention may be also used in the determination of time periods in physiological
work. The mode of using the invention is as follows. Two (or more) electro-
magnetic-styli are placed on the pillar in front of the moving smoked surface, these
styli are in electrical connection with batteries and screens of stretched wire or
strips of Dutch metal, the screens are placed at a determined distance apart, on the
gun range, when the screens are sucessively cut by the projectile the styli sucessively
fall and mark the smoked surface, while the styli are marking a tuning fork trace
is made on the smoked surface, parallel with the two markings of the styli, the
number of vibrational periods of the fork between two styli markings gives the
duration of the time between the cutting of the screens and hence the velocity of
the projectile. The instrument automatically fires the gun by means of an electric
brake which is knocked over by the carriage in its passage in front of the styli.
The tuning fork is started at the desired moment either by means of a hammer or
by means of a revolving disc of leather charged with resin and brought into contact
with the fork for a time sufficient to set it in vibration. The carriage is liberated
by means of a lever.
Dated this 4th day of September 1894.

page_text: I, FREDERICK JOHN SMITH, M.A., F.R.S., Trinity College, Oxford, Clerk in
Holy Orders, Millard Lecturer in Mechanics, Trinity College, Oxford, do hereby
declare the nature of this invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
The object of my invention is to furnish a means for determining small periods
of time, such, for example, as the time of the flight of a projectile over a space of
twenty feet.
The invention may also be used in the determination of time periods in
physiological work.
The way in which I carry my invention into effect is somewhat as follows:-
A carriage furnished with three grooved wheels, runs on two parallel and nearly
horizontal rails, made of hard material. This carriage propelled by means of a
spring, or by a falling weight, which acts upon the mass of the carriage for a given
time and then ceases to act thereon. I attach to the carriage a heavy fly wheel,
geared to one or more of the grooved wheels on which it runs; this increases the
uniformity of its motion. The carriage is brought to rest by a projection attached
to its back running between two leather bands. The carriage carries a smooth
surface, which may be smoked; this receives markings from electro magnetic
styli and tuning forks. A pillar furnished with geometric slides carries the electro
magnetic styli and tuning fork in front of the carriage. The electro magnetic
styli are so constructed that two successive markings can be obtained when
required from one scribing point when two currents are successively broken.
I also use as cores for the electro magnetic styli, spiral springs of iron placed within
a solenoid; the springs contract in length when magnetized and expand when
demagnetized. I also use in some electro magnetic styli, an armature, which can
be partly released by breaking one circuit, and entirely released by breaking
another current, so that two successive markings are made by the same scribing
point. I read the traces or markings on the smoked surface by means of a species
of beam compass furnished with two legs at right angles to the beam, each of which
carries a lens or small microscope for showing the exact terminations of a time
trace the legs are adjusted by means of a screw with a divided head.
And in order that my invention may be more clearly understood and readily
carried into effect, I will proceed aided by the accompanying drawings, more fully
to describe the same.
Fig. 1 is an elevation and Fig. 2 is a plan showing the carriage provided with a
smooth surface for receiving traces together with its supporting track, propelling
and stopping gear, and stylus carrier stand.
Fig. 3 is a similar elevation to Fig. 1, but without the stylus carrier stand and
showing the carriage at the commencement of its motion.
Fig. 4 is an end view of Fig. 3, and Fig. 5 is a cross section of the chronograph
carriage supporting rails.
a is the carriage, which is furnished with three grooved wheels a¹ a² a³ which
run on rails bb made of some hard material, preferably of steel. This carriage a
is propelled along the rails by means of a spring c, or it may be by a falling
weight, which acts upon the mass of the carriage for a given time; the spring
acts upon a driving rod c and the latter is retained in position when the spring c
is compressed and is liberated, when required, by means of a catch d operated by
a hand lever d¹ or by other suitable means. The carriage has a heavy fly wheel a
geared or attached to the axis of one or more of the grooved wheels a a² a³; in the
drawings the fly wheel is shown fixed on the axis of the wheel a²; by means of

page_text: this fly wheel at the uniformity of the motion of the carriage is increased when
said motion is slow. When a very high velocity of the carriage is required, the fly
wheel a is removed; for different velocities, fly wheels of different masses are used.
After the carriage a has been propelled by the action of the spring c and driving
rod c¹ thereon, it is, at the end of its traverse, brought to rest by a projection a
at its back running between two bands e e, usually of leather, kept tight by means
of springs el el. The carriage a carries a smooth surface a', which may be smoked;
this receives markings from electro.magnetic styli and a tuning fork. The whole
instrument above described rests in a V groove at V, a hole at A and on a plane
at U; the feet fare provided with screws capable of rotation by means of the
milled heads for the purpose of adjustinent. The approximate length of the
chronograph from the foot fat one end to those at another is conveniently seven
feet, but I do not confine myself to this length.
Figs. 6 and 7 are two elevations at right angles to each other, Fig. 8 is a plan
and Fig. 9 is a horizontal cross section on the line 9. 9. of Fig. 6, showing a
vertical pillar provided with a carrier for electro magnetic styli and a tuning fork,
so that when the pillar is placed in front of the moving smoked surface as,
the styli and tuning fork may be brought into contact with such smoked surface a.
Fig. 10 is an end elevation of the carrier drawn to an enlarged scale.
The pillar consists of a casting 9 of rectangular section formed with two
V grooves g' along its length, one on each of two opposite sides thereof, as shown
at Figs. 6 to 9; in these grooves g are placed cylindrical pieces h¹ of reduced
diameter in their middle and attached to flat metal slabs forming the stylus
carrier; these slabs are pressed towards each other by means of a screw h² attached
to one slab and a nut on the end of such screw bearing against the other slab, an
elastic washer being interposed between such nut and slab; the screw 2 passes
through the long slot g² in the pillar g. The pillar terminates with a circular
base 9, which rests upon the triangular base g¹ and is capable of rotation about a
stud fitting in a circular hole in said triangular base. By means of a screw i
furnished with a milled head and extending lengthwise through the pillar and
passing through a tapped projection * fixed to one of the slabs h, the carrier can
be raised and lowered as required. The parts of the pillar g which require to be
finished and made true are the V grcoves g' and the elongated faces g, on which a
projection on each slab rests. Both sides or slabs of the carrier are similar,
except that only one of them has the tapped projection, and true fitting is
obtained by means of the simple construction described and pressure applied
through the screw h². The styli and tuning fork are carried in V grooves h' across
the face of one of the slabs. The pillar rests in front of the moving smoked
surface as of the chronograph with its feet 9' in three grooves G forming angles
of 120° to each other in the position shown at Figs. 1 and 2, or in a V groove, a
hole and a plane as previously described with reference to the carriage track. The
ject 9 are screwed through the base 9 and are adjustable by means of milled
heads g.
Instead of constructing the carrier as shown and described with respect to
Figs. 6 to 10, it may be similar to that hereinafter described with respect to
Figs. 14, 15.
Fig. 11 is a plan, Fig. 12 is a side elevation and Fig. 13 is an end elevation of
apparatus by which I measure the distances between two or more time traces.
This consists of a base j having a V groove j¹ cut across its face; in this groove
slides a cylindrical piece k attached to a T shaped beam k. The middle part of
the cylindrical piece is reduced in diameter so that only the two cylindrical ends
thereof are in contact with the V groove j¹. The beam k is also provided with a
V groove k² lengthwise thereof, and in this groove slide cylindrical pieces ll
attached to adjustable carriages or legs consisting each of a flat piece of material l.
These cylindrical pieces are in all respects, except size, similar to the cylindrical
piece. The carriages or legs 1, in addition to the lines of contact of the
cylindrical piece k¹ rest on points, studs or small surfaces 1, and are slightly

page_text: clamped to the long limb of the beam k by means of springs 13, as shown at Figs. 12
and 13; each carriage or leg is also provided with a vernier 1, which traverses
the scale ³. The beam k is also pressed against the base ; by a spring k* similar
to the spring 13. The base jis furnished with a scale parallel to the groovej.
Each of the carriages or legs 1 carries a small microscope 15. While the beam k is
free to move along the groove j¹, that is, across the base j, the carriages or legs
are free to move lengthwise of the long arm of the beam k, so that the distance
between any two points in the plane of the base j, over which the microscopes can
be placed, can be measured. For the purposes of exactitude the microscopes 15 are
furnished with cross wires as is well understood. I also, in some instances, prefer
to make the beam k with a joint at k, so that the long arm k³ can be set at any
required angle with the short arm k¹ thereof.
Fig. 14 is a plan of a part of the beam k and of a carriage or leg 1 thereon,
showing a modified form of such carriage or leg and of mounting it on and securing
it to the beam, and Fig. 15 is a cross section of Fig. 14. The long arm of the
benin khas a V groove k² lengthwise thereof, as in the arrangement shown at
Figs. 11, 12, 13, and a flat surface parallel with the V groove ²; it also has
a groove on its underside terminating at its angle in a slot ; a piece
of metal fits the groove k³, and the middle part of such piece is reduced
in diameter, so that it touches the groove only at its ends; the piece 1º is
attached to the carriage or leg 1 by means of two conically pointed screws .
The carriage or leg is also provided with a hemispherical piece 18, which
is free to take up its position in a recess 1° of conical or pyramidal shape
having three faces; the flat of the hemisphere 18 rests upon and moves
along the flat surface ko. The carriage or leg is kept in position on
the beam k by means of the screw and nut 10 and a piece 11 which slides in the
V groove k on the underside of the beam k. The microscope is screwed into
the hole. The only parts which require to be finished are the V grooves k² k
and the flat ; the rest of the casting or material may be left rough, the con-
struction with the V grooves and flat ensure correct motion for the carriage
or leg 1.
Fig. 16 is a side view and Fig. 17 is an end view of one form of electro magnet
stylus suitable for carrying my invention into effect. It consists of two electro
magnets m m² furnished with armatures n n¹ carried by a Ț shaped lever n². This
lever is pivotted at a point o¹ to one end of a lever o, which is moved from the
poles of the electro magnet by a spring o³. n³ is a slot which works over a pin p
projecting from the lever o and limits the movement of the T shaped lever n².
An adjusting screw q limits the extent to which the lever o is moved by the
spring 2
When the circuit in m¹ is broken, the centre o¹ is displaced to the
right and the vertical arm n of the lever n' is deflected upwards; if, after this
has taken place, the circuit in m is broken, said vertical arm n is deflected down-
wards by means of a coiled spring around the pivot o¹, so that two events are
registered by means of one scribing point on the smoked surface a6 of the
chronograph. The stylus is represented about twice the full size employed.
I also, as shown at Fig. 18, use as cores for styli, spirals r of iron wire which
contract when a current flows in the solenoid, but suddenly expand when the
current is broken; the spiral is attached to an L-shaped lever n² furnished with
a scribing point nt. The styli are carried on the carrier h of the pillar 9 by means
of the tail piece u, and their points are so adjusted as to just touch the smoked
surface a of the chronograph in an inclined direction. The scribing points are
made of aluminium or of other light and hard material.
Fig. 19 represents a stylus which makes successive markings with successive
breaks of two circuits.
When the circuit in the electro magnet s is broken, the lever n² is released and
the end n is, by a coiled spring around its pivot o¹, caused to bear on the armature
lever t, the scribing point n being moved somewhat downwards; when the circuit
in the electro magnet s¹ is broken, the armature lever t is released and also the end n*

page_text: of the lever n², which causes the scribing point n to move still further downwards;
in each case the release is made by breaking the circuits.
Fig. 20 is a side view and Fig. 21 is an end view of a tuning fork provided with
a tracing point and with means for vibrating the same.
vvare the arms of the tuning fork, one of which has the tracing point fixed
to the end thereof. The tuning fork is fixed by its stem 2 in one of the grooves h
of the carrier of the pillar g, see Figs. 6 and 10, so that its tracing point is in
position to just touch the smoked surface a of the chronograph in an inclined
direction. is a socket within which is mounted the axis of a lever w carrying
a wheel w², the face of which is covered with leather or other suitable material
charged with resin. This socket is also attached to the carriage h by means of
the stem v³. The wheel w is rotated by an endless cord a, which passes over a
grooved pulley w³ fixed to the wheel w and over two pulleys y y. The lever wis
capable of being rotated through a small angle in the socket, which angle may
be limited in any suitable manner. The lever w can be moved by the handle w to
place the wheel w² in and out of position for vibrating the tuning fork. The
wheel or rubber w² is driven from an electric or other suitable motor by means of
the endless cord a, and when rotating, it is brought into contact with the tuning
fork for a few seconds; this throws the latter into vibration; the point v¹ consists
of a piece of aluminium attached to one leg of the fork. By these means the fork
can be set vibrating without being injured in any way.
At Fig. 22 I have a V groove, such as is employed to receive the hemispherical
end of one leg of instruments herein described; at Figs. 23 and 24 1 have shown
a vertical section and a plan of a hole such as is employed for receiving the
hemispherical end of a second leg of such instruments; this hole has three sides as
shown.
The mode of using the invention is as follows:-
:-
Two or more electro magnetic styli fixed to the carrier h of the pillar g are
placed in front of the moving smoked surface a; these styli are in electrical
connection with batteries and screens of stretched wire or strips of Dutch metal ;
the screens are placed at a determined distance apart on the gun range. When the
screens are successively cut by the projectile, the styli successively fall and mark
the smoked surface a; while the styli are marking, a tuning fork trace is made
on the smoked surface a parallel with the two markings of the styli; the number
of vibrational periods of the fork between the styli markings gives the duration of
the time between the cutting of the screens and hence the velocity of the projectile.
The instrument automatically fires the gun by means of an electric break at =,
Fig. 2, which is knocked over by the carriage a on its passage in front of the styli.
The tuning fork is started at the desired moment either by means of a hammer or
by means of a revolving disc of leather charged with resin and brought into contact
with the fork for a time sufficient to set it in vibration, as before described. The
carriage a is liberated by means of the lever das before explained. In
physiological work the instrument is used in a similar manner to that in which the
well known pendulum myograph is used, when the contraction of muscle is being
experimented on.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
CLAIMS.
1. The method of measuring the velocity of projectiles and other quickly moving
bodies, and of controlling the velocity of the moving surface of a chronograph
between wide limits, so that the instrument may be used either in physiological
research and experiments, or for measuring the high velocity of projectiles,
1. The method of measuring the velocity of projectiles and other quickly moving
bodies, and of controlling the velocity of the moving surface of a chronograph
between wide limits, so that the instrument may be used either in physiological
research and experiments, or for measuring the high velocity of projectiles,
substantially as herein shown and described.
2. The method, substantially as berein shown and described, of bringing the

page_text: chronograph carriage to rest without any shock or jar whereby the position of the
surface receiving the traces might be shifted.
3. The simple geometric construction of a pillar for carrying electro-magnetic
styli and a tuning fork used in connection with the moving surface of a chronograph,
so that an accurate traverse is obtained with a few finished parts and several traces
may be obtained in succession on the same moving surface, and a method of starting
a tuning fork into vibration by means of a revolving leather wheel charged with
resin, substantially as herein shown and described.
4. An electro magnetic stylus used in connection with the moving surface of a
chronograph in which successive markings may be obtained with one stylus by the
successive breaking of two currents, substantially as herein shown and described.
5. A spiral of iron as the core of an electro magnet used in connection with a
chronograph stylus, substantially as herein shown and described.
6. An optical beam compass furnished with geometric slides and capable of being
set at any required angle, substantially as herein shown and described and for the
purpose stated.
7. The various improvements in chronographic apparatus substantially as herein
shown and described.
Dated this 22nd day of May 1895
HARRIS & MILLS,
23 Southampton Buildings, London, W.C., Agents.