IMPROVEMENTS IN SPRING BALANCES OR WEIGHING MACHINES. AND IN DYNAMOMETERS
Year: 1861

page_text: LETTERS PATENT to John Silvester, of the Firm of George Salter and
Company, of West Bromwich, in the County of Stafford, Manufacturers,
for the Invention of "IMPROVEMENTS IN SPRING BALANCES OR WEIGHING
MACHINES. AND IN DYNAMOMETERS."
Sealed the 4th June 1861, and dated the 13th April 1861.
PROVISIONAL SPECIFICATION left by the said John Silvester at the
Office of the Commissioners of Patents, with his Petition, on the 13th
April 1861.
I, JOHN SILVESTER, of the Firm of George Salter and Company, of West
Bromwich, in the County of Stafford, Manufacturers, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN SPRING BALANCES OR
WEIGHING MACHINES, AND IN DYNAMOMETERS," to be as follows:-
My Invention consists, firstly, in arranging the parts of a spring balance or
weighing machine in the following manner, so as to produce a simple and
inexpensive weighing machine. I make the case of the form of a quadrant
near the curved lower edge, of which the graduated scale is made. The spring
or springs are suspended vertically in the case, and the hook on which the
article to be weighed is hung is fixed by a rod to the lower end of the spring
or springs. On the top of the rod which carries the hook is a rack, which
engages in a pinion near the top of the case, the axis of the pinion carrying an

page_text: index finger, which traverses the graduated scale. Or the said rod may be
connected with the axis carrying the index finger by means of a short lever.
My Invention consists, secondly, in protecting the springs of the balance,
known as Salter and Company's registered spring balance. In the said
balance as hitherto constructed the springs are exposed at the back of the
balance. I protect the said springs by means of a back which I attach to the
front plate, or the back and front plate may be cast in one piece. The bottom
of the back is open to allow the springs to pass out when they elongate in the
act of weighing.
My Invention consists, thirdly, in placing the dial plate and index finger
of dynamometers horizontally, that is, on the base of the instrument, and at
right angles to the direction in which the force to be measured is applied.
The motion is transmitted from the vertical rod to the index figure by means
of a bell crank lover or quadrant, by which means the direction of the motion
is changed from vertical to horizontal. The horizontal position of the dial
plate renders it more convenient for examination than tho vertical position.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Silvester in the Great Seal Patent Office on the 9th
October 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
SILVESTER, of the Firm of George Salter and Company, of West Bromwich,
in the County of Stafford, Manufacturers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of April, in the year of our
Lord One thousand eight hundred and sixty-one, in the twenty-fourth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Silvester, Her special licence that I, the said Jolin Silvester,
my executors, administrators, and assigns, or such others 'as I, the said
John Silvester, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
SPRING BALANCES OR WEIGHING MACHINES, AND IN DYNAMOMETERS," upon the
condition (amongst others) that I, the said John Silvester, my executors or
administrators, by an instrument in writing under niy, or their, or one of their

page_text: hands and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said John Silvester, do hereby declare tho
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:-
My Invention consists, firstly, of a spring balance or weighing machino
constructed in the manner herein-after explained and illustrated in Figures 1, 2,
and 3 of the accompanying Drawings, the object of my Invention being so to
arrange the parts of the balance or machine that a simple and inexpensive
balance or machine is produced..
case.
Figure 1 of the Drawings represents a front elevation of a balance or
weighing machine constructed according to this part of my Invention;
Figure 2 is a side elevation of the same, and Figure 3 is a front elevation of
the same, with the front plate of the case removed for the purpose of shewing
the interior of the said balance or weighing machine. The same letters of
reference indicate the same parts in Figures 1, 2, and 3 of the Drawings.
I make the case a of the balance of a quadrant form, or the said case may bo
made of the form of any other part of a circular disc; and near the curved
edge of the said case the graduated scale b is fixed by screws, as represented
in Figure 1. c, d, are the springs of the balance, suspended vertically in the
The said springs are secured at one end to the fixed cross bar e, and at
the other end to the moveable cross bar f. The latter cross bar f is fixed on
the upper end of the vertical rod or bar g, to the lower looped end of which
the hook h (or a scale pan) is hung, on which hook or scale pan the article to
be weighed is placed. Above the rod y carrying the hook is another rod or
arm i, having a slight motion on the axis k in the forked upper end of the
said rod g. The upper end of the rod or armi is made into a rack 1, the
teeth of which engage in the teeth of the pinion m.
The axis of the said
pinion m passes through the plate a at the front of the balance, and carries at
its end an index finger or pointer n, which traverses the graduated scale b, and
indicates thereon the weight of the article hung on the hook h. The parallel
vertical motion of the bar or arm i is preserved so as to keep the teeth of the
rack in gear with the teeth of the pinion m by the small coiled spring o.
Instead of connecting the bar i to the axis which carries the index finger n by
means of a rack and pinion, the said bar i may be connected with the said axis.
I

page_text: by means of an arm or lever on the said axis jointed to the said bar i. The
balance is suspended by the ring p passed through the loop q, the said loop
being made in one piece with the back and sides of the case a. In using the
balance it is suspended by the ring p, and the article to be weighed is placed
upon the hook or on a scale pan suspended to the loop of the lower rod g.
By the weight of the article placed on the hook h the coiled springs c, d, are
elongated, and the rods g and i are allowed to descend until the weight of the
article on the hook his counterbalanced by the elasticity of the clongated
springs c, d. By the descent of the rod or arm i the rack 7 gives motion to the
pinion m, which said motion is transmitted to the index finger or pointer n on
the axis of the said pinion, and the said finger or pointer is made to traverse
the graduated scale 6, and indicate thercon the weight of the article on the
hook h. On the removal of the article from the hook h, the springs c, d,
return to their compressed condition, and the other parts of the balance
assume the relative positions represented in the Drawings.
back of the
attach to the
The bottom
My Invention consists, secondly, in protecting the springs of the balance
known as Salter and Company's registered spring balance. In the said
balance as hitherto constructed the springs are exposed at the
balance. I protect the said springs by means of a back which I
front plate, or the back and front plate may be cast in one piece.
of the back case is open to allow the springs to pass out when they clongate
in the act of weighing. Figure 4 represents in front elevation a balance
of the kind last explained, made according to this part of my Invention ;
Figure 5 is a side elevation of the same, and Figure 6 is the same with
the front plate removed. The same letters indicate the same parts in
Figures 4, 5, and 6.
a is the back case by which the springs b, b, of the balance are protected,
the said case being open at its bottom. The upper ends of the springs are
connected to the bar c, which bar is secured to or made in one piece with
the said back case a. The lower ends of the springs are secured to the
moveable bar d, the lower part of which bar d is prolonged and has a loop e
at its end, the said loop carrying the hook f on which the article to be weighed
is hung. The said moveable bar d is nearly of the same size as the open
bottom of the back case a, and when the springs are in their normal position
the said bar d nearly closes the bottom of the said back case a. A flange g
is made on the back and ends of the said bar din such a position that when
the said bar is in its normal position, that is, raised to its greatest height
in the case a, the said flange 9 bears against the bottom of the case a and
completely closes it. a² is a circular flange on the back case a to which

page_text: the front plate h of the balance is fixed; i is a loop cast in one pieco with
the back case a, to which loop i the ring k is connected by which the balance
is suspended. When a weight is placed on the hook f, the springs b, b, are
elongated and the bar & descends, the said springs b, b, passing out through
the open bottom of the case a, as represented in Figure 4. When the
weight is removed from the hook f the springs b, b, return to their normal
position, taking with them the bar d, the bar d and flange g on it closing the
bottom of the back case a.
My Invention consists, thirdly, in placing the dial plate and index finger
of dynamometers' horizontally, that is to say, on the base of the instrument,
and at right angles to the direction in which the force to be measured is
applied, and in arranging the parts of dynamoneters as herein-after explained
and illustrated in Figures 7, 8, 9, and 10 of the accompanying Drawings.
The horizontal position of the dial renders it more convenient for examination
than the vertical position as in ordinary dynamometers.
Figure 7 represents in side elevation a dynamometer constructed according
to my Invention; Figure 8 represents a vertical section of the same, and
Figure 9 represents a transverse section of the same, and Figure 10 represents
a plan of a portion of the same. The same letters indicate the same parts
in Figures 7, 8, 9, and 10.
a is the base plate of the dynamometer, carrying at one end a tube or
bollow cylinder b, having in it a coiled spring c, the force applied in ordor
to extend or elongate the said spring being measured by the instrument.
The other end of the base plate a carries rods d, d, which rods and the
upper end of the tube or cylinder 6 support the plate e, upon which the
dial fand other upper parts of the dynamometer are supported. The spring c
is hooked at bottom by the hook g to the base of the instrument, and at
top by the hook h to the arm or bar i, the upper screwed end of which
carries the handle k by which the dynamometer is used. The lower part
of the bar i has a slot made in it, as best seen in the front view of the
said bar in Figure 9, in which slot a connecting rod m works, being jointed
at its lower end to the said arm or bar i, and at its upper end to one
arm n of the bell crank lever or quadrant n, n, the said bell crank lever
or quadrant turning ou a centre at o on the plate e of the instrument.
The other arm 22 of the bell crank lever or quadrant n, n², is connected to
the horizontal bar p, having a rack p² at its end, the teeth of which rack
engage in the teeth of the pinion 2 on the axis r carrying the index finger s.
By pulling or raising the bar or arm i vertically by means of the handle k,
the coiled spring c is expanded or elongated and the amount of expansion

page_text: or, elongation is measured in the following manner.:-As the arm or bar i
is raised the connecting rod m in the slot is raised at the same time,
and the said rod m raises the right arm of the bell crank lever n, n², the
said lever turning on its centre. o, the arm n³, consequently, moves nearly
horizontally. The direction of the motion of the rod or arm i is thus
changed from vertical to horizontal. The horizontal motion is transmitted
through the bar p to the rack p³, which rack gives motion to the pinion g
and its motion is communicated to the index finger s, which index finger
traverses the graduated dial f and indicates thereon the force which has
been applied to, the handle k. On loosing the handle the spring c returns
by its clasticity to its contracted condition, and the parts of the dynamometer.
assume the relative positions represented in the Drawing. The teeth of
the rack p² are kept in gear with the teeth of the pinion q during the
motion of the said rack p² by the small coiled spring t, seo Figures 8 and 10.
I have already explained with reference to Figure 1, that the graduated
scale is secured to the front of the case by screws, that is to say, the
graduation is made on brass or white metal and attached to the other part
of the case, which is made of iron or other inexpensive metal. This part
of my Invention is applicable to all kinds of spring balances or weighing
machines and dynamometers, whether the graduated part of the dial be
curved or straight. By making that part only of the dial plate which
carries the graduation of brass or white metal, and the other part of iron
or an inexpensive metal instead of making the whole of the dial of brass or
white metal, great economy of material is effected.
Having now described the nature of my Invention, and the manner of carry-
ing the same into effect, I wish it to be understood that I do not limit
myself to the precise details herein described and represented in the Drawings,
as the same may be varied without departing from the nature of my Inven-
tion; but I claim as my Invention,―
Firstly, the improvement or improvements in spring balances or weighing
machines, herein-before described and illustrated in Figures 1, 2, and 3 of the
accompanying Drawings, that is to say, arranging or combining the parts
of a spring balance or weighing machine so as to produce a simple and
inexpensive spring balance or weighing machine, essentially in the manner
herein-before described and illustrated in the said Figures 1, 2, and 3 of the
accompanying Drawings.
Secondly, the improvement in spring balances of the kind herein-before
explained and illustrated in Figures 4, 5, and 6 of the accompanying
Drawings, that is to say, protecting the springs of the said balance by

page_text: means of a back case open at its bottom, through which open bottom
the springs may pass when elongated by the weight hung on the balance.
Thirdly, the improvements in dynamometers herein-before described and
illustrated in Figures 7, 8, 9 and 10 of the accompanying Drawings, that is
to say, placing the dial plate and index finger of dynamometers horizontally
and arranging the parts of dynamometers essentially in the manner herein-
before described and represented in the said Figures 7, 8, 9, and 10 of the
Drawings.
Fourthly, making the graduated parts of the dials of spring balances or
weighing machines, and dynamometers of brass or white metal, and the other
parts of the dials of iron or other inexpensive metal, the said graduated parts
being made separately and attached to the other parts of the dials by screwing
or otherwise.
In witness whereof, I, the said John Silvester, have hereunto set my
hand and seal, this Seventh day of October, in the year of our Lord
One thousand eight hundred and sixty-one.
Witness,
GEORGE SHAW.
JOHN SILVESTER. (L.B.)