IMPROVEMENTS IN BALANCES OR MACHINES FOR WEIGHING
Year: 1871

page_text: LETTERS PATENT to James Murdoch Napier, of York Road, Lambeth,
in the County of Surrey, for the Invention of "IMPROVEMENTS IN
BALANCES OR MACHINES FOR WEIGHING."
Sealed the 8th August 1871, and dated the 22nd February 1871.
PROVISIONAL SPECIFICATION left by the said James Murdoch Napier
at the Office of the Commissioners of Patents, with his Petition,
on the 22nd February 1871.
I, JAMES MURDOCH NAPIER, of York Road, Lambeth, in the County
of Surrey, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN BALANCES OR MACHINES FOR WEIGHING," to be as follows:-
This Invention has for its object improvements in balances or machines
for weighing.
I load the one end of the weighing beam or balance with a sufficient
constant weight and the other end with the load to be weighed along
with a weight or weights, the sum of which with the load to be weighed
approximatively equals the constant weight or counterpoise at the other

page_text: end of the beam. When so loaded I set the beam free for weighing by
opening a pair of holding grippers. The beam and its load is thus
allowed to be actuated by and will swing or vibrate according to the
difference which there may happen to be between the loads attached to
its two ends, the excess or preponderating weight which may be at the
one end becoming the moving force. Upon the amount of this pro-
ponderating weight will depend the extent of the are through which the
ends of the beam will move. When the beam has had its swing and has
arrived at the full extent of its vibration, I cause it to be arrested and
held by the closing of the grippers, the timing of the actions of which I
arrango so as to be in unison or as nearly as possible in accordance with
the time taken by the beam to perform its vibration. When the beam
is thus held, the length of the are through which it has passed in its
vibration is measured and shewn upon a dial, and from this indication
the difference between the loads at the two ends of the beam can be
ascertained, and consequently the weight of the load weighed, account
being taken of the quantities of the weight or weights which may be
used to act in conjunction with the load weighed. When the difference
between the loads at the two ends of the weighing beam is greater
than the indicating power of the machine, or so as to cause the beam
to vibrate beyond its proper limit, the weigher adjusts the amount
of weight acting with the load to be weighed more nearly, so that the
load on that end of the beam may more nearly balance the constant
weight at the other end.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Murdoch Napier in the Great Seal Patent
Office on the 22nd August 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
MURDOCH NAPIER, of York Road, Lambeth, in the County of Surrey,
send greeting.
-
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of February, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said James Murdoch Napier, Her special

page_text: license that I, the said James Murdoch Napier, my executors, admi-
nistrators, and assigns, or such others as I, the said James Murdoch
Napier, 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 "Ix-
PROVEMENTS IN BALANCES OR MACHINES FOR WEIGHING,” upon the condition
(amongst others) that I, the said James Murdoch Napier, my executors
or administrators, by an instrument in writing under my, or their, or
one of their 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 Scal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said James Murdoch Napier do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say :-
This Invention has for its object improvements in balances or machines
for weighing. I load the one end of the weighing beam or balance with
a sufficient constant. weight, and the other end with the load to be
weighed along with (when necessary) a weight or weights, the sum of
which with the load to be weighed approximately equals the constant
weight or counterpoise at the other end of the beam. When so loaded I
set the beam free for weighing by opening a pair of holding grippers or
otherwise. The beam and its load is thus allowed to be actuated by and
will swing or vibrate according to the difference which there may happen
to exist between the loads attached to its two ends, the excess or pre-
ponderating weight which may be at the one end becoming the moving
force. Upon the amount of this preponderating weight as well as upon
the position of the centre of gravity of the beam in relation to its centre
of action or oscillation, and to the amount of pendulous counteracting
weight in the beam, will depend the extent of the arc through. which the
5 ends of the beam will move. When the beam has had its swing, and has
arrived at 'the full extent of its vibration, I cause it to be arrested and
held, which may be effected by the closing of the grippers. The timing
of the actions of the disengaging and holding or fixing, apparatus. I

page_text: arrauge so as to be in unison or as nearly as possible in accordance with
the time taken by the beam to perform its vibration. When the beam
is thus held the length of the arc through which it has passed in its
vibration is measured, and may be shewn upon a dial or otherwise, and
from this indication the difference between the loads on the two ends of
the beam can be ascertained, and consequently the weight of tho load
weighed. When the difference between the loads at the two ends of
the weighing beam is greater than the indicating power of the machine
(represented by the amount of pendulous weight on the under side of
the beam, and the extent allowed for the beam to vibrate), or so as to
cause the beam to vibrate beyond its proper limit, the "weigher"
adjusts the amount of weight acting with the load to be weighed more
nearly so that the load on that end of the beam may more nearly
balance the constant weight at the other end. By employing a constant
counterpoise a beam may be always charged with the same or nearly the 1
same total weight, and the times of the vibrations will remain nearly
constant. If the counterpoise be altered and the charge on the beam
changed so as to affect seriously the times of the vibrations of the beam,
the movements of the apparatus for releasing and holding the beam
should be timed accordingly.
•
Figure 1 is an elevation part in section shewing my Invention applied
to a balance of ordinary construction. A is the weighing beam; B, the
supporting frame; O, the levelling frame guided at the top in frame B,
and furnished with V rests at the ends of its arms for receiving the 2
projecting pins at the ends of the beam; D is the scale pan; D', the load
to be weighed; Dare make-up weights; D³, the constant counterpoise;
the indicating lever a is pivoted behind the beam at a'; cam a² actuates
the lever a, which is slicwn depressed by the cam, and so is raised at the
other end, which is furnished with a toothed segment gearing with a 3
pinion upon spindle which passes through the dial plate E, and carries
the pointer a*. On the spindle behind the dial plate is a pulley with
'cord and weight a³ attached, which serves to balance the longer end of
lever a, and to keep it up to the cam and also to keep the teeth of the
pinion in contact with those of the segment; 6 are grippers for holding a
and releasing the beam, they operate upon the segment 6' and are
actuated by cam 6ª on spindle F.

page_text: Figure 2 shews a plan of the grippers 6 drawn to a larger scale.
To open the grippers cam 63 acts against roller and forces wedge
piece b* forward, compressing spring 6. The spiral spring & then pulls
the long arms of the grippers towards one another. The closing takes
place by the power of spring b³, when the cam ceases to operate against
roller. The levelling frame C is actuated by cam c on spindle F,
which cam operates against a roller upon lever c', the motion being
communicated through connecting rod c², lever c³, and connecting
rod c; the frame C is guided at bottom in guide c³. Balance weight c
serves to raise frame C and to level the beam; the cam c acts to raise
weight c and lower frame C. The power to actuate the machine is
applied to spindle F by means of the mitre wheels d, d¹, spindle d³,
pinion, and wheel d', which is fixed on spindle d³. This spindle
carries loose upon it a barrel, upon which cord d' is wound. To this
cord is suspended a weight sufficient for driving the apparatus. For
winding up the weight a toothed wheel is provided fast with the barrel,
and a pinion on handle spindle d'. The usual train of wheels in such
movements connects spindle d³ with the regulating fly d³. The barrel
is provided with a pawl, which plays into a ratchet fast on spindle d³, so
as to admit of the winding up of the weight while the spindle con-
nections are at rest. The operation of weighing is effected by the
"weigher" depressing the starting lever e, and so disengaging the stop
lever e¹ from catch e* fastened to disc e' on spindle F. The spindle with
its cams and catch disc then turns in the direction of the arrow until
catch e comes round and meets the stop lever e', by which time the
weighing will have been completed and indicated upon the dial E.
Upon a second pressure on lever e and disengaging of stop lever e¹ the
movement will be continued until catch e' comes again against the stop
lever e', by which time the parts will have returned to their first position,
and the instrument will be again ready for weighing upon the starting
lever e being depressed. If preferred the catch e³ may be dispensed with
and the cams so arranged as to allow of an interval of rest for the
indicating pointer sufficient for the "weigher" to note the results. The
cams, three in number, are formed to operate in the following order :-
When the stop is disengaged for weighing, cam c first depresses levelling
frame C, then cam 6 opens grippers b, and the beam is set free to
vibrate. As soon as it has completed its vibration the grippers are
closed by their cam, and the beam is held in the position it has assumed,
cam a³ now acts by allowing the long end of lever a to rise, and so to
=

page_text: lower the other end until it comes in contact with the stop pin ƒ placed
on that end of the beam. This action of lever a brings round the
pointer to indicate on the dial plate the dip of the lever, and con-
sequently the position of the beam. The first space passed over by the
pointer to zero representing minus quantities, and that on the other side
plus quantities. At this point of the revolution catch arrives against
stop e', and the movements are brought to a stand, until the "weigher
having take note of the result again touches the lever e, when cam aª
returns lever a to its first position. Cam 6³ next opens the grippers,
after which cam c allows weight to raise levelling frame O, and
B
finally cam closes the grippers. By this time a complete revolution
has been made, and catch e' has again arrived against stop lever c¹, the
balance weight at the end of lever e' serves to return it to its position.
Figure 3 illustrates an application of my Invention to weighing
machines which are actuated continuously, such as machines for
weighing coins, or coin blanks, in which the articles to be weighed
are fed on to the weighing place from a hopper or reservoir G auto-
matically in succession. The pieces are placed for weighing by slide g
actuated by cam g' through lever ², the spring keeping the lever
against the cam. In this Figure the action of the levelling bar C is
reversed, its ends passing into slots in the weighing pendants, so that
the beam is levelled by the downward action of the bar C. The
arrangements for actuating the indicating pointer and for measuring
the vibration of the beam are also varied. The sliding feeler his raised
by the weight h¹ through its connection with the spindle of the pointer
pulley and the pinion which gears with the small rack upon fecler /,
and is depressed by cam a through lever and its connection with
pulley upon spindle h. The proportions of the pulleys connecting
the pointer with the feeler give the pointer in this instance greater
range, so that it makes two turns for the whole extent of indication, the
first representing minus quantities, and the second plus quantities. The
grippers are shown in this case to be actuated through a lever; the cams
are somewhat varied in form to allow of rest for noting the indications,
and of time for the additional cam g' to place the piece on the weighing
plate. If preferred, instead of disengaging the beam for weighing by
opening the grippers it may be done by raising the levelling bar C, the
grippers being used for fixing the beam at the end of its vibration; tho
beam is fixed in this instance by the grippers laying hold of one of the

page_text: weighing pendants. In order to adjust the speed of the movement
shown in Figure 1 for driving the machine, so that the times of the
actions for disengaging and holding the beam may accord with the
times of the vibrations of the beam, the weight attached to cord de may
be varied, and for further adjustment the fans of the governing fly may
be angled more or less; any other suitable motive power may be used
for actuating my improved balances and weighing machines, but the
power employed should be regular in speed, or should be regulated by
the governor, for this reason hydraulic motors would be very suitable.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I claim,
the construction of balances or machines for weighing with mechanism
for setting free the beam, and then after it has been allowed time to
swing stopping and retaining it, so that the weight of the load weighed
may be known from the position the beam has attained.
I also claim the application of mechanism to measure the arc through
which the beam swings in weighing, substantially as described.
I also claim the general arrangement of mechanism, substantially as
herein described and shewn by the annexed Drawings.
In witness whereof, I, the said James Murdoch Napier, have here-
unto set my hand and scal, this Twenty-second day of August,
in the year of our Lord One thousand eight hundred and
seventy-one.