A Mechanical Method of and Instrument for Taking and Plotting Levels in a Continuous Section.
Year: 1896

page_text: Date of Application, 8th Dec., 1896
Complete Specification Left, 7th Sept., 1897-Accepted, 8th Jan., 1898
PROVISIONAL SPECIFICATION.
A Mechanical Method of and Instrument for Taking and Plotting
Levels in a Continuous Section.
I, ALEXANDER THOMAS FRASER, Colonel in the Corps of Royal Engineers, on the
Retired List, residing at Redburn, Inverness, Scotland, do hereby declare the nature
of this invention to be as follows:-
This invention relates to the construction of a surveying instrument on a principle
that has not hitherto been attempted, in which by means of two equal perambulator
wheels connected at their centres by a bar & moving a style attached to the middle
of a straight rod in a fixed direction & at a constant rate whilst the rod and style
are given a separate downward movement along the direction of an arm inclined to
the rod by means of an integrating mechanism the style repeats upon a sheet of
paper behind it the curve of the ground to any reduced scale wanted from the pole of
the instrument, which is kept vertical by an inertia pendulum.
The use of two equal perambulator wheels, a moveable roll of drawing paper, a
style carried on a rod provided with a parallel motion and which moves across the
paper, while the motion of the rod in the vertical plane is regulated by an inclined
arm to which is fixed a sliding carrier connected to, integrating mechanism, while
the pole of the arm is kept always vertical by an inertia pendulum, and a bar to give
the tangent to the surface, is a combination different from any that has hitherto
been employed in levelling operations.
When the apparatus travels along level ground, the inclined movement of the bar
carrying the tracing style, & its horizontal motion, are so proportioned that the
style draws a vertical line. When however the ground rises or falls a cam on the
pendulum at O alters the position of a disc in frictional contact with & driven by
a cone, which in turn receives its motion from the wheel of the perambulator. In
this way the inclined movement of the bar is accelerated or retarded, & the pencil
deviates from the vertical line indicating the incline or decline of the ground.
To enable my invention to be fully understood I proceed to describe the same
by reference to the accompanying drawings in which Figure 1 is the side view
& Figs. 2, 3 & 4 are details of the tracing mechanism for plotting levels in a
continuous section constructed according to this invention. Similar letters in Figs. 1
to 4 are used to denote similar parts.
The instrument is based on the mathematical principle of the differential Calculus,
that where y is the angle between the radius vector of a curve at the point whose
polar coordinates are r & 6, and the tangent to the curve at that point: then
Cos. =
dr
that is, when the are S is increasing at the rate ds the rate of the
increase of the radius vector is dr Cos. ds.
The present invention has for object to apply this principle in a practical
manner as follows. The path followed by a perambulator wheel on the ground may
be treated as a curve line whose length is ascertainable from the running of the
wheel,, & it only remains for a style to be given a transverse motion in proportion to
the distance run, and a directed motion in the line of the radius vector proportional

page_text: to the inclination of the radius vector to the tangent of the curve of the ground at
each instant of time, for the natural section of the ground to appear on the paper
before it on a reduced scale, and on reaching the lower edge of the paper, style &
paper are carried up and reset to make the section continuous.
A suitable arrangement for carrying out the invention is constructed as follows. 5
Two perambulator wheels of equal diameter & convenient size, shown in the drawing
Figure 1 as bicycle wheels whose centres are A & A are connected by a rigid
frame A a b c d 'A' in the journals at those centres, in which the axles are free to
turn. The distance between centres therefore represents with sufficient accuracy the
element ds of the curve of the ground. It is obvious also that the straight line 1
connecting the centres-or a b the bar which is parralel to that line-will be in the
direction of the tangent to the curve of the ground at every instant.
An inertia pendulum M N is made to swing on a pivot at O, having its hobs at
M & N inversely proportional in weight to the squares of the distances ON and OM,
which keeps the pendulum steady while being moved. A convenient point 1 is 1
taken as the pole-see Figure 1.-upon the pendulum, & at this point there is
mounted a pulley 01 with which is geared the screw-shaft with forced thread v PS
which constitutes the effective part of the radius arm. At a horizontal distance O'Q
equal to O P, namely that between the axle of the pendulum & the pole, there is a
fixed support e Q carrying a sleeve, in which the radius arm is free to turn & slide as 2
the frame of the perambulator moves off this level.
The system YW W Y forms a parallel motion, the shafts WY & WI Y being
pivotted at the ends of the supports y y'. The radius arm is pivotted to the
pendulum at P, & passes through a pivotted sleeve at v.
The paper D D D D is secured in a frame fitted with rollers after the manner of
a plane-table, and is set behind the radius arm, square as shown in Figure 1 with the
tangent of the curve of the ground, and at the most suitable distance back to take
the point of the tracing style, its plane being truly vertical.
The pole P bisects the width of the paper, and is set conveniently near the top of
the paper.
The style or pencil is fastened at the back of the Rod R R under the point G,
Figure 1 and detail drawing Fig. 2, so as to press lightly on the paper. On com-
mencement of work the pencil G must be brought exactly below the pole P.
The rod fits easily & slides in a sleeve n of Figure 2, with provision like that
shown in the case of ee Figure 3 for the style to pass it is necessary & if given a
motion in the plane of the vertical by the carrier m which is moved upwards or
downwards by the forced thread screw S of the same pattern & pitch as that of
telegraph printing apparatus & similarly mounted.
This motion is not proportional to the distance passed over by the wheels except
when travelling on level ground but varies with the inclination of the ground as
afterwards described.
The horizontal motion of the rod is proportional to the distance traversed by the
wheels as will be shewn subsequently.
It takes place in the direction of the arrow, viz. right to left in Figure 1, by the
lantern cog T, which slides freely on the shaft WY, but revolves with it communi-
cating motion to the horizontal rod R R'. The shaft W Y is pivoted on the fixed
support of y' g, & the centre y is on the same level as O & Q. The way in which
this pivoting is arranged by means of a subsidiary shaft a a b b so as to allow the
cog to pass the whole depth of the paper is shewn full size in Fig. 3. This shaft WY
is driven from the shaft A Z by means of a chain passing over the pulleys WZ the
slack of which is taken up by a spiral spring w
The rod is held in position by an idle cog T sliding on the axis W Y, which is
pivoted at y to the framing which supports the paper frame-or to a klf.
The ratchet wheel a on which the pawl bears either way with sufficient stiffness
allows the style to be brought to the middle of the paper when it has drawn the
section up to the edge, in order to begin afresh. A bridge c c & swivel bearing e
keep the rod R in engagement with the lantern wheel. There is the same arrange

page_text: ment at cog T. The rod R R' has rack pins d d Fig. 3 all along the inner side to
engage with the lantern cog.
The rotation of the axis CX is conveyed to the screw shaft V S of the radius arın
by a chain passing round pulleys at X, Z & P the last driving the bevel wheels
01 & 0 Fig. 2.
The radius arm V S is similar in construction to the armature screw of a printing
telegraph instrument with a train of wheelwork in the case g unnecessary to describe
in detail. There are three fixed rods r of Fig. 2 which screw into the side of the
box q & the rectangular plate S e to support the radius arm & the one of these
immediately behind the screw shaft goes through the sleeve at Q Fig. 1 to keep the
arm in the radial direction. As soon as the carrier M is brought by the forced
thread of the screw V S to the end of its downward run, it is sprung up by the
mechanism in box g to place at the pole P ready to commence travelling down
& tracing the level of the ground again.
All that now remains is to give the carrier m, which the forced thread of the screw
moves down the radius arm, the motion proportional to dr equal to Cos. ds.
The mechanism for this purpose-see Figure 1-consists of the toothed pinion B
at the axle A of the perambulator wheel, which drives a large toothed wheel F, whose
pinion V drives the bevel wheel U on the axle A Z. Close to the upper side of the
bevel wheel is the differentiating cone H, which turns with the axle. A dise K (sliding
on the cones slant surface) is made to revolve by the friction on the cone, & the
disc turns the axle C X which passes through the sleeve I. This sleeve is drawn
back by the spiral spring C K, and the wheel K is moved with it. The rotation of
the axis CX is conveyed to the screw shaft V S by a chain as just previously described.
An arm J is attached to the upper end of the sleeve ending in a flexible inetal band
As the
which is fastened at the upper end of the curve of cosines on the cam L.
pendulum swings the band is either released or wound on or off over the successive
tangential points of the curve making the disc K revolve with a velocity varying
differentially as Cos. . The cam is fast upon the axis of the pendulum so as to swing
with it and alter the position of the wheel K on the cone. Instead of a cone & disc
any equivalent mechanism-such as a wheel & disc-may be employed.
On the outer edge of the cam is the curve of Cos. to a convenient radius
extending as far as is required to be used for gradients not exceeding about 1 in 4. The
way this curve is to be constructed is illustrated in Fig. 4 in which O P is the polar
distance of Figure 1, and each of the two quadrants are by way of approximation
divided into 9 sectors by radii from the centre O, radii from the pole P being drawn
through all the points where radii drawn from O intersect the semicircle. If
then be taken equal to Cor. 450 (to radius O P), Z' will be a point in the curve
of the cam-If Q Z be equal to Cos. (55°-5°) then Z" willbe another point of the
curve, & so on.
The height of the frustum of the cone will extend the slant height on which the
dise K slides to the length of an are of about 20° (to a suitable radius) on each side
of an intermediate or zero diameter, shown by a dotted line in Figure 1. The
diameters of the cone H, & disc K, also the curvature of the cain L, are to be so
proportioned in any case, that when the disc is on the zero line, & and the ground is
fevel, the style will trace a vertical straight line on the paper. The extreme
diameters of the frustum H being made such that when the pendulum swings 14°
either way, the line will be deflected the same number of degrees to one side or other.
This is the prime adjustment on which the working of the instrument depends.
For, as the motion of the style G in the direction of the radius arm V S is faster or
slower than its transverse motion in the direction R' R in the proportion of the cosine
of the angle at every instant, the perpendicular line traced on level ground will be
deflected with the rise or fall of the ground, so that the style will trace on the paper
the curve of the ground to a reduced natural scale as the instrument is moved
along it.
When the style G, & rod RR', reach the bottom of the paper, they are drawn up
to P again by the spring of the telegraph printing armature inside the box g. The

page_text: paper is simultaneously wound up (by the handle E in the absence of any self acting
mechanism) till the extremity of the section plotted is brought under the point of
the style, ready to commence a fresh length of section, & this procedure is continued
till the paper gives no room for more.
The instrument is then stopped, the style set to the middle of the paper, & a new
piece of section commenced. Eventually the sections are joined on to each other as
required. It will facilitate the work if the paper has ruled on it a number of parallel
lines to serve as lines of datum.
Dated this twentieth day of November one thousand eight hundred and ninety-
A Mechanical Method of and Instrument for Taking and Plotting
Levels in a Continuous Section.
I, ALEXANDER THOMAS FRASER, Colonel in the Corps of Royal Engineers, on
the Retired List, residing at Redburn, Inverness, Scotland, 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:-
This invention relates to the construction of a surveying instrument on a principle
that has not hitherto been attempted, in which by means of two equal perambulator
wheels connected at their centres by a bar & moving a style attached to the
middle of a straight rod in a fixed direction & at a constant rate, whilst the rod &
style are given a separate downward movement along the direction of an arın
inclined to the rod by means of an integrating mechanism the style repeats upon a
sheet of paper behind it the curve of the ground to any reduced scale wanted from
the pole of the instrument which is kept vertical by an inertia pendulum.
The use of two equal perambulator wheels, a movable roll of drawing paper,
a style carried on a rod provided with a parallel motion and which moves across the
paper, while the motion of the rod in the vertical plane is regulated by an inclined
arm to which is fixed a sliding carrier connected to integrating mechanism, while
the pole of the arm is kept always vertical by an inertia pendulum, and a bar to
give the tangent to the surface, is a combination different from any that has hitherto
been employed in levelling operations.
When the apparatus travels along level ground, the inclined movement of the
Iar carrying the tracing style, and its horizontal motion, are so proportioned that
the style draws a vertical line. When however the ground rises or falls a cam on
the pendulum at O alters the position of a disc in frictional contact with and driven
by a cone, which in turn receives its motion from the wheel of the perambulator.
In this way the inclined movement of the bar is accelerated or retarded, and the
pencil deviates from the vertical line indicating the incline or decline of the ground.
To enable my invention to be fully understood I proceed to describe the same by
reference to the drawing accompanying my Provisional Specification in which
Figure 1 is the side view & Figures 2, 3 and 4 are details of the tracing mechanism
for plotting levels in a continuous section constructed according to this invention.
Similar letters in Figures 1 to 4 are used to denote similar parts.
The instrument is based on the mathematical principle of the differential
calculus, that where is the angle between the raidus vector of a curve at the point
whose polar coordinates are and , and the tangent to the curve at that point:
dr
then Cos. = - that is, when the arc S is increasing at the rate ds the rate
ds
of increase of the radius vector is dr
=
Cos. + ds.

page_text: The present invention has for object to apply this principle in a practical manner
as follows. The path followed by a parambalar wheel on the ground may be treated
as a curve line whose length is ascertainable from the running of the wheel, and
it only remains for a style to be given a transverse motion in proportion to the
distance run, and a directed motion in the line of the radius vector proportional to
the inclination of the radius vector to the tangent of the curve of the ground at
each instant of time, for the natural section of the ground to appear on the paper
before it on a reduced scale, and on reaching the lower edge of the paper, style and
paper are carried up and reset to make the section continuous.
A suitable arrangement for carrying out the invention is constructed as follows.
Two perambulator wheels of equal diameter and convenient size, shown in the
drawing Figure 1 as bicycle wheels whose centres are A and A are connected by
a rigid frame A a bed A. in the journals at those centres, in which the axles
are free to turn. The distance between centres therefore represents with sufficient
accuracy the element d. s. of the curve of the ground. It is obvious also that the
straight line connecting the centres--or a b the bar which is parallel to that line--
will be in the direction of the tangent to the curve of the ground at every instant.
An inertia pendulum M N is made to swing on a pivot at O, having its bobs
at M and N inversely proportional in weight to the squares of the distance ON
and OM, which keeps the pendulum steady while being moved. A convenient
point P is taken as the pole-see Figure 1-upon the pendum, and at this point
there is mounted a pulley 01 with which is geared the screw-shaft with forced
thread PS which constitutes the effective part of the radius arm. At a
horizontal distance O Q equal to O P, namely that between the axle of the
pendulum and the pole, there is a fixed support e Q carrying a sleeve, in which
the radius arm is free to turn and slide as the frame of the perambulator moves off
the level.
The system YW W Y forms a parallel motion the shafts W Y and W Y being
pivotted at the ends of the supports y, y'. The radius arm is pivotted to, the
pendulum at P and passes through a pivotted sleeve at w
The paper D D D D is secured in a frame fitted with rollers after the manner
of a plane-table, and is set behind the radius arm, square as shown in Figure 1 with
the tangent of the curve of the ground, and at the most suitable distance back to
take the point of the tracing style, its plane being truly vertical.
The pale bisects the width of the paper, and is set conveniently near the top
of the paper.
On
The style or pencil is fastened at the back of the Rod R R under the point G
Figure 1 and detail drawing Fig. 2, so as to press lightly on the paper.
cominencement of work the pencil G must be brought exactly below the pole P.
The rod fits easily and slides in a sleeve n of Figure 2 with provision like that
shown in the case of e. e Figure 3 for the style to pass it if necessary and is given a
motion in the plan of the vertical by the carrier m, which is moved upwards or
downwards by the forced thread screw v S of the same pattern and pitch as that of
telegraph printing apparatus and similarly mounted.
This motion is not proportional to the distance passed over by the wheels except
when travelling on level ground but varies with the inclination of the ground as
afterwards described.
The horizontal motion of the rod is proportional to the distance traversed by the
wheels as will be shewn subsequently.
It takes place in the direction of the arrow, viz., right to left in Figure 1 by the
lantern Cog T, which slides freely on the shaft W₁ Y, but revolves with it com-
municating motion to the horizontal rod R R. The shaft W Y is pivoted on the
fixed support y¹g and the centre y¹ is on the same level as O and Q. The way in
which this pivoting is arranged by means of a subsidiary shaft a a. b b so as to
allow the cog to pass the whole depth of the paper is shewn full size in Fig. 3.
This shaft W Y is driven from the shaft A Z by means of a chain passing over the
pulleys W Z the slack of which is taken up by a spiral spring W.

page_text: The rod is held in position by an idle cog T sliding on the axis WY, which is
pivoted at y to the framing which supports the paper frame-or to a k. l. f.
The ratchet wheel x on which the Pawl bears either way with sufficient stiffness
allows the style to be brought to the middle of the paper when it has drawn the
section up to the edge, in order to begin afresh a bridge c c and swivel bearing e. e.
keep the rod R in engagement with the lantern wheel.
There is the same arrangement at cog T. The rod R R¹ has rack pins d d Fig. 3
all along the inner side to engage with the lantern cog.
The rotation of the axis CX is conveyed to the screw shaft v S of the radius arm
by a chain passing round pulleys at X Z and P the last driving the bevel wheels 01
and O Fig. 2.
The radius arm v S is similar in construction to the armature screw of a printing
telegraph instrument with a train of wheelwork in the case q unnecessary to describe
in detail. There are three fixed rods r of Fig. 2 which screw into the side of the
box q and the rectangular plate S a to support the radius arm and the one of these
immediately behind the screw shaft goes through the sleeve at Q Fig. 1 to keep the
arm in the radial direction. As soon as the Carrier m is brought by the forced thread
of the screw v S to the end of its downward run, it is sprung up by the Mechanism in
box q to place at the Pole P ready to commence travelling down and tracing the level
of the ground again.
All that now remains is to give the carrier me which the forced thread of the screw
moves down the radius arm, the motion proportional to dr equal to Cos. ds.
The mechanism for this purpose-see Figure 1 consists of the toothed pinion Bat
the angle A of the perambulator wheel," which drives a large toothed wheel F',
whose pinion V drives the bevel wheel U on the axle A Z. Close to the upper
side of the bevel wheel is the differentiating cone H, which tuins with the axle. A
disek (sliding on the cones slant surface) is made to revolve by the friction on the
cone, and the dise turns the axle CX which passes through the sleeve I. This
sleeve is drawn back by the spiral spring C K, and the wheel K is moved with it.
The rotation of the axis C X is conveyed to the screw shaft v S by a chain as just
previously described. An arm J is attached to the upper end of the sleeve ending in
a flexible metal band which is fastened at the upper end of the curve of cosines on
the Cam. I. As the pendulum swings the band is either released or wound on or off
the successive tangential points of the curve making the disek revolve with a velocity
varying differentially as Cos. . The cam is fast upon the axis of the pendulum so as
to swing with it and alter the position of the wheel k on the Cone. Instead of a Cone
and disc any equivalent mechanism-such as a wheel and disc-may be employed.
On the outer edge of the Cam is the curve of Cos. to a convenient radius
extending as far as is required to be used for gradients not exceeding about 1 in 4.
The way this curve is to be constructed is illustrated in Fig. 4 in which O. P is the
polar distance of Figure 1, and each of the two quadrants are by way of
approximation divided into 9 sections by radii from the centre 0, radii from
the pole P being drawn through all the points where radii drawn from O
intersect the semicircle. If then QZ be taken equal to Cos. 45° (to radius O P), Z
will be a point in the curve of the Cam.-If Q Z" be equal to Cos (55°-°)
then will be another point of the curve, and so on.
The height of the frustum of the Cone will extend the slant height on which
the disc K slides to the length of an are of about 20° (to a suitable radius) on each
side of an intermediate or zero diameter, shown by a dotted line in Figure 1. The
diameters of the Cone H, and disc K, also the curvature of the Cam L, are to be so
proportioned in any case, that when the dise is on the zero line, and the ground is
level, the style will trace a vertical straight line on the paper. The extreme
diameter of the frustum I being made such that when the pendulum swings 14°
either way, the line will be deflected the same number of degrees to one side or
other. This is the prime adjustment on which the working of the instrument
depends,
For, as the motion of the style G in the direction of the radius arm V S is faster
or slower than its transverse inotion in the direction R R in the proportion of the

page_text: Cosine of the angle at every instant, the perpendicular line traced on level
ground will be deflected with the fall or rise of the ground, so that the style will
trace on the paper the curve of the ground to a reduced natural scale as the
instrument is inoved along it.
When the style G, and rod R R¹, reach the bottom of the paper, they are drawn
up to P again by the spring of the telegraph printing Armature inside the box G.
The paper is simultaneously wound up (by the handle E in the absence of any self
acting mechanism) till the extremity of the Section plotted is brought under the
point of the style, ready to commence a fresh length of Section, and this procedure
is continued till the paper gives no room for more.
The instrument is then stopped, the style set to the middle of the paper, and a
new piece of Section commenced. Eventually the Sections are joined on to each
other as required. It will facilitate the work if the paper has ruled on it a number
of parallel lines to serve as lines of datum.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed I declare that what I
claim is
Firstly; A surveying instrument constructed to measure its own distances and
heights as it is rolled along the ground, and simultaneously to plot a continuous
section of the ground it is run over to a suitable scale on a web of drawing paper
the operation of the instrument being based upon the ratio which subsists between
a curve, its tangent angle and its radius vector, as herein before described.
Secondly. The combination of parts forming the improved instrument for taking
and plotting levels arranged and operating substantially as herein before described
and represented in the accompanying drawing.
Thirdly-The two perambulator wheels connected by a bar to give the tangent
direction of the curve of the ground as hereinbefore described.
Fourthly. The inertia pendulum to reduce irregularity of vibration, due to
wheeling along, to a minimum, and to keep the pole vertical as described.
Fifthly: The gearing to impart a rate of motion to the rod which carries the style
across the paper proportionate to the speed of the perambulator wheels on the
ground, as well as the ratchet wheel to allow backward slip of the style when
required, or it has to be reset, all as hereinbefore described, and represented in the
accompanying drawing.
Sixthly The radius vector arm with its forced threaded screw and other mechanism
as used in the armatures of printing telegraphs to give, as controlled by the inclined
spindles, a differential movement to the style obliquely downwards in a special ratio,
as before described, and represented in the drawing.
Seventhly The combination of laterally moving rod with style affixed, carried
at a rate varying with the inclination of the ground from top to bottom of successive
portions of a web of paper, to trace a curve proportional to the curve of the ground
thereon, thus taking and plotting a section continuously in the manner and by the
means substantially as set forth.
Eighthly The curve of cosines on a cam which is attached to & swings with the
pendulum to regulate the differential motion of the style as herein before described.
Ninethly The integrating cone & disc (or mechanical equivalent) used in
combination with the inertia pendulum the curve of cosines & the mechanism as
described & for the purposes set forth.
Tenthly The winding up of the paper after the style has sprung up to the pole
at the end of its run in order to continue the section as already herein described.
Taded his Seventh dev of January One thousand eight hundred and ninety