IMPROVEMENTS IN APPARATUS FOR WEIGHING
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
WILLIS, of the University of Cambridge, Clerk, Jacksonian Professor, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twelfth day of February, in the third year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto me, the said Robert
Willis, Her especial licence, full power, sole privilege and authority, that I,
the said Robert Willis, my exors, admors, and assigns, or such others as I,
the said Robert Willis, my exors, adiñors, or assigns, should at any time
agree with, and no others, from time to time and at all times during the term
of years therein expressed, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
my Invention of "IMPROVEMENTS IN APPARATUS FOR WEIGHING;" in which said
Letters Patent is contained a proviso that I, the said Robert Willis, shall
cause a particular description of the nature of my said Invention, and in what
manner the same is be performed, to be inrolled in Her said Majesty's High
Court of Chancery within six calendar months next and immediately after the
date of the said in part recited Letters Patent, as in and by the same, reference
being thereunto had, will more fully and at large appear.
NOW KNOW YE, that, in compliance with the said proviso, I, the said
Robert Willis, do hereby declare the nature of my said Invention, and the
manner in which the same is to be performed, are fully described and ascer-

page_text: (that is to say):-
My Invention is for the purpose of weighing various articles with great
expedition.
DESCRIPTION OF THE DRAWING.
Figure 1 is a plan of the machine. Figure 2 a vertical section made along
the line k, g, of the plan. Figure 2 is an elevation of the machine. The
same letters of reference are applied to the same things in all these Figures.
A, B, a, b, is a rectangular frame, which constitutes the beam of the balance.
This is formed of two similar pieces A, B, a, b, the form of one of which is
seen in Figure 2. These pieces are kept at the proper distance by pillars or
other framework, as at c, d, and there is a knife edge at E, e, fixed to them.
The frame of the machine is formed of two parallel plates of a similar form
F, G, f, g, the shape of one of which is seen in Figure 2. These plates
are fixed at the proper distance asunder, by means of pillars or other well
known contrivances, as at h, H, and the whole may be attached to a board
or pedestal. The knife edges E, e, rest in holes or cups attached to the
plates of the frame, and formed in any manner usual to scale makers, so that
the beam of the balance may turn freely thereon. At B, b, the beam is
provided with other knife edges or suspending pieces of any usual form, for
the reception of the scale which is to receive the article to be weighed, and
which may be made in any form that is thought best adapted to receive it.
The scale pan which I prefer, and which is represented in the Figures, is
that which is usually denominated a Medhurst pan. The weights employed
are shewn at L, 1, M, m, N, n, P, p, Q, q. I have for the sake of simplicity
merely shewn five in the Drawing, but a greater or a lesser number may be
used. These weights I prefer to be of a long and narrow shape, and I usually
make them of such a form as may be turned in a lathe for the convenience
of manufacture. At each end of the weight (one of which is represented
separately at Figure 3), two necks are provided, as at a, b, and c, d. The plates
of the frame have a series of curved openings 1, 2, 3, 4, 5, Figure 2, the
breadths of which are somewhat greater than the diameters of the extremities
(a, a, Figure 3) of the weights, and the weights when not in use lie in and
rest upon the bottoms of these openings, in the manner shewn in the Figures,
but are prevented from escaping from the frame by the shoulders between the
grooves, and by the looped form of the openings in which they lie. On the
upper edge of each side of the balance beam are formed angular notches, as

page_text: at I., II., III., IV., V., each pair of which corresponds to one of the weights,
and is so placed that when the beam rises, each pair of opposite notches will
be brought in succession under its appropriate weight, and will lift it up by
means of the necks already described (b, c, Figure 3), which are provided for the
purpose. The action of the machine will be best shewn by an example :-Let
the machine be formed to measure the weight of any article in ounces. In
this case the gravity of every separate weight must be so proportioned to the
distance of its beam notches from the fulcrum or central knife edges E, e,
that its mechanical effect upon the scale pan may equal one ounce. If a
body weighing less than an ounce be placed in the scale, the end B of the
beam will descend, and the opposite extremity rise, until the first pan of
notches I strike against their weight L, L. Before the beam can move any
further, the weight must be lifted, but as its effect upon the scale is equal
to one ounce, and the body is less than an ounce, the beam will remain with
its notches in contact. If a body weighing more than one ounce, and less
than two, be put into the scale, the first weight will be lifted, and the second
pair of notches II will be brought into contact with the weight M, m, in
which position the beam will rest. If a body weighing more than three
ounces and less than four be put into the scale, then the three weights
L, L, M, m, N, n, will be raised one after the other, and the pair of notches
IV. will rest in contact with the fourth weight P, p, and so on. An index
plate may be connected with the beam in any convenient manner, as for
example, by placing it at the end of the beam, at R, S, and making its edge
concentric with the extremity of the beam, marks being engraved opposite
to the beam in each position, and number appended to them to indicate the
corresponding weight; then if any article is placed in the scale, the beam will
immediately assume a position corresponding to its weight, by taking up (in
the way just described) the required number of loose weights, and will thus
shew with great rapidity the weight of the article in ounces, pounds, or
according to any other unit or series of weights that may have been
assumed, and to which the separate loose weights have been made equivalent.
And it is important to remark, that it will be evident that, according to my
Invention, the weights when taken up by the beam act for the time being
as if each weight was part of the beam itself, there being no swing or action
of the weight with respect to the beam. Instead of engraving the weights
upon the index plate, the price to be paid for such weight of the article
may be engraved, as for example, postage, if the machine be constructed to
weigh letters, or both weight and price may be made to appear; but this I
do not claim. I generally adjust the weight of the beam, so that it will require

page_text: a weight equivalent to the first in the series, to raise it from its lowest position
into contact with the first moveable weight, by which means one weight of
the series will be saved, but this is not essential. In the Figures, as there
are five moveable weights, and the beam is supposed to preponderate, as above
described, it is evident that any weight greater than six ounces will raise the
last weight Q, q, and that the weight of any article, if greater than six ounces,
cannot be measured. Let a pair of notches T, t, be formed in any convenient
part of the beam, and such a weight be placed in them as will, together with
the weight of the beam, exert a mechanical effort equal to six ounces on the
scale pan, then any weight greater than six ounces, and less than seven, will
raise the beam into its second position, with the notches in contact with the first
moveable weight, and in like manner the weight of any body less than twelve
ounces will now be measures by the machine. By providing several of such
additional weights, the scale or range of weights that the machine is capable of
measuring may be extended at pleasure. I would remark, that to ensure the
perfect action of the balance, the line which joins the centres of motion B and
E of the scale pan and beam, should pass through the centres of gravity of
every weight when it lies in the beam notches, as well as through the centre
of gravity of the beam itself. The order in which the weights are raised is
indifferent, provided they be raised in succession; thus the extreme weight
Q, q, might be raised first, and so on; also the rack may be placed within
the beam, so that the beam may act upon the extreme grooves a, d, Figure 3,
of each weight, and the rack upon the intermediate ones c and b, and various
other changes may be made in the arrangement and form of the machine,
which will readily suggest themselves to scale makers and mechanies. I do
not therefore confine myself to the precise form or arrangement shewn.
I sometimes make a machine in a form which is explained by Figure 4.
C, A, B, represents a scale beam of any usual form, of which A is the centre,
and from the extremity B is to be suspended a scale pan or other ordinary
receptacle. From the opposite extremity of the beam C is suspended another
scale pan, of which D, E, is a side view, and which is furnished with a
link f, g, below, in the manner of the common Medhurst pan, by which it
is prevented from swinging. A series of weights a, b, c, d, e, f, of the same
form as Figure 3, are supported in a rack attached to the fixed frame of the
machine, and the two opposite sides of the suspended scale pan D, E, have
each a series of angular notches, every opposite pair of which lies below one
of the weights, so that when the pan D, E, rises from the action of any
article in the opposite scale pan, these notches meet, and take up in
succession as many of the weights as are required to counterbalance it, exactly

page_text: in the same manner as in the machine first described. I have not thought it
necessary to shew the requisite frauling to carry the fulcrum of the beam,
and the rack which supports the weights, in their proper places. In this
form of machine, two or more pans may be placed one above the other, for
the purpose of taking up the weights, or the pan which takes up these
weights may be made in various forms; also the weights may be placed either
transversely to the beam, as in the Figure, or they may be parallel to it, or
otherwise disposed, it being only essential that they shall be placed at a
distance horizontally and vertically from each other, and properly to be
taken in succession by the pan, and when taken to retain them from movement
in respect to the pan. I do not claim the principle of causing the scale beam
or suspended frame of a balance to raise weights in succession, various con-
trivances for that purpose having been used before; but what I claim is,-
First, the mode of constructing weighing machines, wherein the beam is
caused to take up successively a series of weights, in such manner that when
taken up, each weight is so held as to be without swing or action in respect to
the beam.
Secondly, I claim the mode of constructing weighing machines, whereby
a series of weights are successively taken up, each being placed separate, and
vertically and horizontally distant from each other, by a scale, and wherein
the weight will be retained without swing or motion in respect to the said
scale.
In witness whereof, I, the said Robert Willis, have hereunto set my hand
and seal, this Tenth day of August, in the year of our Lord One thousand
eight hundred and Contr