IMPROVEMENTS IN INDEX SCALES
Year: 1878

page_text: LETTERS PATENT to John Clayton Mewburn, of 169, Fleet Street, in the
City of London, Patent Agent and Consulting Engineer, for the Invention of
IMPROVEMENTS IN INDEX SCALES." A communication from abroad by Julius
Post of Hamburg in the German Empire.
"
Sealed the 29th April 1879, and dated the 4th November 1878.
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn at
the Office of the Comminissioners of Patents on the 4th November 1878.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN INDEX SCALES." [A com-
munication from abroad by Julius Post, of Hamburg, in the German Empire.]
This Invention refers to a new system of scales in which the index will absolutely
indicate small weights; it refers to index scales particularly, for weighing without
the use of weights, and it further refers to single levered and double levered scales
including the use of weights, in which latter case the index will indicate on the
segmental scale the smaller divisions of weight, and will thus fulfil those duties
which are done in scales for chemical purposes by the adjusting or shifting weight
or rider.
This system of scales will therefore be especially useful for analytical purposes,
but it may also be used for paper, sheet, letter, and other scales.
The construction of the scale will admit of making the division on the segment
without the use of an assaying weight, the division is made on the segment by
mathematical construction, and the adjustment of the lever is done according to
this division.
I make the division on the segment by drawing a tangential line to that point
of the segment to which the index indicates when the two fulcrums of the scale are
in one horizontal line, I then divide the afore-mentioned tangential line into so
many parts (say a hundred) as there shall be divisions on the segment, I then draw
straight lines from all the points of divisions on the tangential line to the swinging

page_text: fulcrum of the scale lever, and by thus crossing the segment o
division on it.
In the new system of scales I further make use of two adjusting weights, the one
being capable of being shifted
on the lever in the direction of the index, the other
of being shifted vertically at right angles to the just mentioned direction.
The weight to be adjusted in the direction of the index I use for adjusting the
lever so that the index points to zero.
Now-in-order to make the scale applicable for determination of weight, say up
to one gramme, I put one gramme upon the plate; I then adjust by the adjusting
-weight in a vertical direction; so that the finger indicates to 100, after which all
the subdivisions on the segment will be perfectly true.
In this same manner I can effect by means of the adjusting weight the
adjustment of the scale lever, so that the indication of the finger from-1-to-100-
corresponds to one centigramme or to one milligramme, in fact that each subdivision
on the segment indicates one tenth or one hundredth of a milligramme.
As however bodies of so light a weight have very rarely practically to be weighed,
and bodies of heavier weight than the last mentioned divisions have more frequently
to be weighed, I have constructed the scale which I will now proceed to describe for
the latter purpose.
The frame of the scale rests on 3 points, two of which are adjustable by set
screws, so as to bring the whole scale into true position which is indicated by a
plumb line. The scale lever has its fulcrum at a point where the lever with its
prismatic shaped axle rests upon a flat bearing. On the one end of this lever the
pendant or hoop of the scale plate is suspended. This plate is either constructed
in stories for the hereinafter mentioned purpose, or it consists of a ring only, to
take a cup or a crucible, and for the special purpose hereinafter mentioned to take
a very light ball of glass or metal.
The prolongation of the lever towards the segment is formed by a finger which
swings between two studs, which studs are horizontally fixed to the ends of a
second segment to limit the play of the finger.
In case there are more divisions on the segment in radial direction than one, a
prolongation of the finger surrounds the segment and a fine wire or silk thread is
fixed from the end of the finger to the ends of its prolongation, so that this thread
or wire plays in front of the divisions on the segment. On a suitable part of the
lever I make a screw thread upon which a double nut is adjustable, between this
adjusting weight and the fulcrum a screw passes through the lever, which screw
has a vertical position when the finger indicates at zero, and which screw will
not alter the position of the finger when a double nut thereon is raised or
lowered.
.
The raising or lowering of these nuts will serve to alter the angle of play of the
finger at equal weight on the plate. The screw is kept in position by a nut.
The scale lever may be used in a bent form in order to employ the scale for
-heavier-weights-than-those-above-mentioned, in which case the segment has to be
enlarged accordingly. I further intend to use instead of the adjusting weight a
second plate, and to attach the finger, not at the end of the scale lever, but above
or below the fulcrum point; I further reserve to myself to place the before
mentioned vertical screw with the nut above the fulcrum of the scale lever; in some
cases I may find it advantageous to to arrange instead of the fixed screw a device in
which a weight is placed and made adjustable on a small axle running parallel with
the scale lever; this weight if turned' to one side will for example allow the finger,
if the scale is loaded with one milligramme only, to play at the same angle as if the
weight were turned to the opposite side and the scale loaded with one centi-
gramme.
This scale has heretofore been described as used without actual weights and
will serve,
1. For easily determining the weight of ashes in paper, or the dry contents of
moist substances.

page_text: In determining the ashy contents of paper I put a piece of paper, weigning for
instance 100, in a tube or cylinder made of platinum wire, the tare weight of which
cylinder has to be equilibrated by the adjusting weight. I then place the cylinder
over a hot flame, so that only white ashes will remain in it, and the index or finger
will then directly indicate on the segment the percentage of ashes; in this manner
I may easily determine what quantity of minerals have been mixed with the paper
pulp.
2. Again the scale will serve for determining or finding the weight of one square
meter of paper by weighing one square decimeter.
3. For determining or finding the weight of 500 sheets of paper by weighing
one piece of such paper.
4. Finally, the scale may be used as a barometer or weather gauge. By shifting
the adjusting weights I am enabled to adjust the scale in such a way that the point
of gravity of the lever nearly comes into the fulcrum point, the play of the scale
will then be so sensitive, that in placing a very light body of great bulk, say a ball
of very thin metal on the scale, each alteration in the air surrounding such body or
ball will make the ball rise or fall and consequently will cause the scale to play.
By controlling such play of the scale by means of a corresponding division on the
outer periphery of the segment, the scale may be used as a barometer or weather
guage. I adjust the scale in this case as hereinbefore described.
When the ordinary barometer with a mercury column, for instance, indicates
"fine weather," then I shift the adjusting screw on the lever, so that the finger will
point towards the mark "fine weather." If the mercury borometer indicates "rain
and wind" I then shift the vertical screw so that the finger points to "rain and
wind." Every subsequent barometrical alteration will be precisely indicated by
the scale. I may also make use of the scale by employing weights in order to
ascertain the weight of heavier bodies, and in this case the scale will serve for
analytical purposes.
For this purpose I construct the scale plate in stories for the reception of a series
of weights, which weights may be of corresponding heaviness to the size of scale.
The weight employed (say 20 grammes) is equilibrated by the adjusting weight on
the lever, so that the finger points to zero.
If I now add one further gramme to the scale plate, and then regulate the scale
by the vertical adjusting weight, so that through this additional weight the finger
points to 100, then the divisions on the segment will be equal to centigrammes.
In order now to ascertain the weight of a body I put the same on the scale plate,
remove the weights of the approximate heaviness of the body from the scale, and
add to the sun of such removed weights the further weight indicated by the finger
on the segment.
This method is much more simple than the method now in use by adjusting
through the adjusting piece or rider on scales for chemical purposes.
In order to avoid very large oscillations of the fingers, and also to discharge the
two fulcrums when the scale is at rest, I construct a stop device for this scale
which I call the "parallel stop."
This parallel stop may be constructed for two scale plates. The device consists
of a hollow piece cast to the frame of the scale in which two rods or bars may be
raised or lowered by two excentrics, these eccentrics are fixed on one end of a shaft
situated in bearings.
The two rods have at their lower ends two small antifriction rollers.
One rod partly surrounds the other at a certain distance of its length. At this
length the hollow piece is slotted at two opposite sides, through which slots screws
pass into the outer rod. These screws form the fulcrum for the one end of levers.
which are respectively connected together by cross pieces. These pieces move arms
in their fulcrums, which arms are made capable of turning with one end on pivots
or projections cast to the hollow piece. The arms move the frames by means of
points, and these frames move parallel by means of other and corresponding
arms.

page_text: The distance between the moving points of each of the arms being equal to the
distance between the fulcrums of the scale lever, and these moving points moving
parallel to the axis lines of the avove named fulcrums, therefore cach point of the
frame in its up and down motion will make an analogous movement with the axis
of the fulcrum on which the scale plates hang.
The fulcrum axis is supported by two small vertical columns screwed in the upper
horizontal part.of.one of the abovenamed frames while the scale plate is supported
by the flat button of a set screw traversing through the lower horizontal part of the
-frame.
The second bar or rod moving vertically in the hollow piece by means of the
eccentric below it has at its upper surface a horizontal incision, into which the
prismatical shaped axis of the scale lever takes. A lever is fixed to this bar or rod
taking by its vertical part with forked shaped end underneath the scale lever if the
axis of the latter is raised by the rod.
The scale lever and the scale plate being elevated by means of the eccentrics and
the bars or rods, if now the spindle or shaft (from the exterior of a glass cover,
.covering the entire apparatus) is turned, the axis of the scale lever will be lowered
down on its bearing, while at the instant of this contact (by means of the construc-
tion of the two excentrics) the frame will be lowered so that the axis of the scale
plate will rest upon the bearing of the scale lever. As long as the scale lever is
pressed upon downwardly by the scale plate the axle part of the scale plate is still
supported by the above mentioned small vertical columns and the plate itself is still
supported by the flat button of the screws in the frame. But as soon as the scale
lever has found its equilibrium then these supports move in a downward direction,
and the finger of the scale points on to the segment.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Clayton Mewburn in the Great Seal Patent Office on the
3rd May 1879.
A com-
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN INDEX SCALES."
munication from abroad by Julius Post, of Hamburg, in the German Empire.
This Invention refers to a new system of scales, in which the index will
absolutely indicate small weights; it refers to index scales, particularly for
weighing without the use of weights, and it further refers to single levered and
double levered scales, including the use of weights, in which latter case the index
will indicate on the segmental scale the smaller divisions of weight, and will thus
fulfil those duties which are done in scales for chemical purposes by the adjusting
or shifting weight or rider.
This system of scales will therefore be especially useful for analytical purposes,
but it may also be used for paper, sheet, letter, and other scales.
The construction of the scale will admit of making the division on the segment
without the use of an assaying weight; the division is made on the segment by
mathematical construction, and the adjustment of the lever is done according to this
division.
'I make the division on the segment by drawing a tangential line to that point
of the segment to which the index indicates when the two fulcrums of the scale are
in one horizontal line. I then divide the aforementioned tangential line into so
many parts (say a hundred) as there shall be divisions on the segment, I then draw
straight lines from all the points of divisions on the tangential line to the swinging
fulcrum of the scale lever, and by thus crossing the segment I obtain the required
division on it.
In the new system of scales I further make use of two adjusting weights, the
one being capable of being shifted on the lever in the direction of the index, the
other of being shifted vertically at right angles to the just mentioned direction.
The weight to be adjusted in the direction of the index I use for adjusting the
lever, so that the index points to zero.
Now in order to make the scale applicable for determination of weight, say, up
to one gramme, I put one gramme upon the plate I then adjust by the adjusting
weight in a vertical direction, so that the finger indicates to 100, after which all
the sub-divisions on the segment will be perfectly true.
In the same manner I can effect by means of the adjusting weight the adjust-
ment of the scale lever, so that the indication of the finger from 1 to 100 corre-
sponds to one centigramme or to one milligramme, in fact that each sub division on
the segment indicates one tenth or one hundredth of a milligramme.
As however bodies of so light a weight have very rarely practically to be
weighed, and bodies of heavier weight than the last mentioned divisions have more
frequently to be weighed, I have constructed for the latter purpose the scale shewn
in the annexed Drawings, which I will now proceed to describe.
Figure 1 is a side view, and Figure 2 an end view of a scale constructed
according to this Invention; Figures 4, 5, 8, 10, and 11, are detail views; Figures.
3, 6, 7, and 9, are detail views of parts used for special purposes; Figure 12 is a
scale with the details of Figure 10 applied to it.
The frame A of the scale rests on the three points B, C, (Figure 1), and D
(Figure 2), two of which (B and C) are adjustable by set screws, so as to bring the
whole scale into true position, which is indicated by the plumbline E in the ring F.
The scale lever G has its fulcrum at Z, where the lever with its prismatic shaped
axle rests upon a flat bearing. On the one end of this lever the pendant or
hoop of the scale plate is suspended. This plate is either constructed in stories for

page_text: the hereinafter mentioned purpose, or it consists of a ring only, to take a cup or a
crucible, and for the special purpose hereinafter mentioned to take a very light ball
of glass or metal.
The prolongation of the lever G towards the segment N is formed by the finger I,
which swings between the two studs O and P, which studs.are_horizontally-fixed
-to-the-ends-of-a-second segment to limit the play of the finger I.
In case there are more divisions on the segment in radial direction than one, a
prolongation of the finger surrounds the segment, as shewn in plan in Figure 3;
and a fine wire or silk thread is fixed from the end of the finger to the end of its
prolongation, so that this thread or wire plays in front of the divisions on the
_segment. On a suitable part of the lever G (Figure 1) I make a screw thread,
upon which a double nut K is adjustable; between this adjusting weight and the
fulcrum Z a screw passes through the lever G, which screw has a vertical position
when the finger indicates at zero, and which screw will not alter the position of
finger when the double nut L is raised or lowered.
The raising or lowering of these nuts will serve to alter the angle of play of
the finger at equal weight on the plate. The screw is kept in position by the
nut M.
The scale lever G may be used in a bent form in order to employ the scale for
heavier weights than those above mentioned, in which case the segment has to be
enlarged accordingly. I further intend to use instead of the adjusting weight Ka
second plate, and to attach the finger, not at the end of the scale lever as shewn,
but above or below the fulcrum point. Sometimes I place the screw with the nut
Labove the fulcrum of the scale lever; in some cases I may find it advantageous
to arrange the device shewn in Figure 8 instead of the fixed screw, in which device
a weight is placed and made adjustable on a small axle running parallel with the
scale lever. This weight, if turned to one side (as shewn in the Drawing) will, for
example, allow the finger, if the scale is loaded with one milligramme only, to play
at the same angle as if the weight were turned to the opposite side and the scale
loaded with one centigramme.
This scale has herein before been described as used without actual weights, and
will serve;
(1.) For easily determining the weight of ashes in paper, or the dry contents of
moist substances. In determining the ashy contents of paper I put a piece of paper,
weighing, for instance, 100, in a tube or cylinder made of platinum wire (see
Figure 7), the tare weight of which cylinder has to be equilibrated by the adjusting
weight K.
I then place this cylinder over a hot flame, so that only white ashes will
remain in it, and the index or finger will then directly indicate on the segment the
per centage of ashes; in this manner I may easily determine what quantity of
minerals have been mixed with the paper pulp.
(2.) Again, the scale will serve for determining or finding the weight of one
square meter of paper by weighing one square decimeter.
(3.) For determining or finding the weight of 500 sheets of paper by weighing
one piece of such paper..
(4) Finally, the scale may be used as a barometer or weather gauge. By shifting
the adjusting weights I am enabled to adjust the scale in such a way that the point
of gravity of the lever nearly comes into the fulcrum point; the play of the scale
will then be so sensitive that in placing a very light body of great bulk, say a
hollow ball (Figure 6) of very thin metal void of air on the scale, each alteration in
the air surrounding such body or ball will make the ball rise or fall, and conse-
quently will cause the scale to play. In place of the ball I can screw the complete
cap of an aneroid barometer, see Figure 9, to the beam. The increasing pressure of
the atmosphere will compress this cap, and will thereby cause the approach of the
entire cap towards the fulcrum of the beam, which will consequently become lighter.
The finger of the scale will sink, whereas the reverse will be the case when the
pressure of the atmosphere is decreased. By controlling such play of the scale by

page_text: "
means of a corresponding division on the outer periphery of the segment N, the
scale may be used as a barometer or weather gauge.
I adjust the scale in this case as hereinbefore described.
When the ordinary barometer, with a mercury column; for instance, indicates
fine weather," then I shift the screw K, so that the finger will point towards the
mark "fine weather." If the mercury barometer indicates "rain and wind," I then
shift the screw L so that the finger points to "rain and wind." Every subsequent
barometrical alteration will be precisely indicated by the scale. I may also make
use of the scale by employing weights in order to ascertain the weight of heavier
bodies, and thus the same will form an exact indicator scale of considerable
extent.
For this purpose I construct the scale plate in stories (see Figures 1 and 5) for
the reception of a series of weights, which weights may be of corresponding heavi-
ness to the size of scale. The weight employed (say 20 grammes), is equilibrated by
the adjusting weight K, so that the finger points to zero.
If I now add one further gramme to the scale plate, and then regulate the scale
by the adjusting weight L, so that through this additional weight the finger points
to 100, then the divisions on the segment will be equal to centigrammes..
In order now to ascertain the weight of the body I put the same on the scale
plate, remove the weights of the approximate heaviness of the body from the scale,
and add to the sum of such removed weights the further weight indicated by the
finger on the segment.
This method is much more simple than the method now in use, by adjusting
through the adjusting piece or rider on scales for chemical purposes.
In order to avoid very large oscillations of the fingers, and also to discharge the
two fulcrums when the scale is at rest, I construct a stop device for this scale, which
I call the parallel stop.
In the Drawings I have shewn this parallel stop as constructed for two scale
plates. The device consists of a hollow piece a, Figures 1 and 2, cast to the frame
of the scale in which two rods or bars b and c may be raised or lowered by the two
eccentrics d and e; these eccentrics are fixed on one end of the shaft h situated in
the bearings and g. The two rods b and c have at their lower ends the two small
antifriction rollers i and k.
The rod c partly surrounds the rod b at a certain distance of its length. At this
length the hollow piece a is slotted at two opposite sides, through which slots the
serews and m pass into the rod c (Figures 1, 2, and 4). These screws form the
fulcrum for the one end of the levers o, o, and p, p, which are respectively connected
together by cross pieces n, n, one of which is shewn in Figure 4, the other one is'
indicated only by a dotted centre line. These pieces move the arms u', u², 2³, u³,
in their fulcrums 81, 82, 83, 84, which arms are made capable of turning with one end.
on the pivots or projections t¹, 2, 3, 4, cast to the hollow piece u. The arms
u¹, u², u³, u³, move the frames 1 and 2, by means of the points V1, V2, and these
frames move parallel by means of the arms us, uº, u³, u³.
The distances between the moving points of each of the arms u being equal to
the distance between the fulcrums of the scale lever, and these moving points
moving parallel to the axis lines of the above named fulcrums, therefore each point
of the frame in its up and down motion will make an analogous movement with
the axis of the fulcrum on which the scale plates hang.
It will be seen in Figure 5, in which the scale plate and the hanging fulcrum are
shewn, as supported by the parallel stop device, that the fulcrum axis H is supported
by the two small vertical columns screwed in the upper horizontal part of one of
the above-named frames 7, while the scale plate is supported at W by the flat button
of a set screw traversing through the lower horizontal part of the frame 1.
The second bar or rod b moving vertically in the hollow piece a by means of the
eccentric below it, has at its upper surface a horizontal incision into which the
prismatical shaped axis of the scale lever takes. A lever x is fixed to this bar or
rod b taking by its vertical part with forked shaped end underneath the scale lever,

page_text: .
if the axis of the latter is raised by the rod b. In the Drawing, Figure 1, the scale
lever and the scale plate are shewn as elevated by means of the eccentrics d and e;
and the bars or rods b and c. If now the spindle or shaft h (from the exterior of a
glass cover covering the entire apparatus) is turned, the axis of the scale lever will
be lowered down on its bearing, while at the instant of this contact (by means of
the construction of the two eccentrics, see-Figure-2), the frame will be lowered so
that the axis of the scale plate will rest upon the bearing of the scale lever. As
long as the scale. lever-is pressed-upon downwardly by the scale plate, the axle part
of the scale plate is still supported by the above mentioned small vertical coluinns,
_ and-the-plate itself is still supported by the flat button of the screws in the frame r.
But as soon as the scale lever has found its equilibrium, then these supports move
-in-a-downward direction, and the finger of the scale points on to the segment.
The pivots may be replaced by edges, and the frame 2 (Figure 5) may be used
as a scale, as shewn in Figures 10, 11, and 12. The frame--will then be made to
overbalance either to the one side or the other (see Figures 10, 11, and 12), so that
the edges 1, 2, 3, 4, will be always pressed to their seats, and the frame will rise and
fall in a parallel direction. This frame rests with a flat seat directly on the
fulcrum g, and is supplied with a plate f for the reception of the object to be
weighed, and the set of weights underneath this plate falso presses in a lateral
direction. Lastly, I place on the fulcrum Z of the scale beam, on each side of the
same, disc breaks of which only one s¹ is shewn in Figure 10. These disc breaks
turn concentrically with the axis, and can be so grasped by the lever h with its
fulcrum at d, that in case of a displacement of the axis the same can be replaced in
position, and the beam can likewise be held fast ad libitum at any point.
And having now described the nature of the said Invention and in what manner
the same is to be performed, I declare that I claim as the “Improvements in Index
Scales,"
First. The construction of the division on the segment of the index scale in
combination with the employment of adjusting weights, as herein before described.
Second. The system or construction of one levered index scales for very minute
weighing operations, either without weights or with a set of weights in stories in
combination with a stop device or without the latter, substantially as described
above and shewn in the annexed Drawings, which system or construction may be
used especially for weighing the ashes in paper, for weighing the pressure of the
air, and for other purposes.
Third. The employment of the described system or construction in two armed
index scales and other scales, as above described in combination with the stop
device or without the same.
Fourth. The parallel stop device hereinbefore described and the parallel mode of
guiding on edges with break devices for permitting of a flat axis and edge bearings,
as hereinbefore described.
In witness whereof, I, the said John Clayton Mewburn, have hereunto set
my hand and seal, this First day of May, One thousand eight hundred and