AN APPARATUS FOR EFFECTING AND CHECKING THE ADDITION OF NUMBERS
Year: 1879

page_text: LETTERS PATENT to John Darling, of Glasgow, in the County of Lanark,
North Britain, for the Invention of "AN APPARATUS FOR EFFECTING AND
CHECKING THE ADDITION OF NUMBERS."
Sealed the 11th June 1880, and dated the 13th December 1879.
PROVISIONAL SPECIFICATION left by the said John Darling at the Office
of the Commissioners of Patents on the 13th December 1879.
JOHN DARLING, of Glasgow, in the County of Lanark, North Britain.
APPARATUS FOR EFFECTING AND CHECKING THE ADDITION OF NUMBERS."
"AN
This Invention, which relates to an instrument or apparatus for effecting and
checking the addition of figures or numbers, consists of a rotative disc which is
carried in or upon a flat plate or frame. The outer edge of this disc is notched or
indented, and opposite each notch or indent is a number of the series into which
the disc is divided, for example, 50, 100, or other suitable number. Near to the
edge of the rotative disc is an arc on which is a series of numbers from 1 progressing
upwards to any desired number.
When it is required to add any numbers together the numbers are succes-
sively read on the fixed arc, and a pointer is placed in the notch in the
rotative disc opposite each such number, by which the rotative disc is turned
round until reaching a stop which is placed for checking its further rotation. The
result is read off on the rotative disc, a portion of which is seen through an
opening in the plate by which it is partly covered. For the purpose of adding
together numbers whose total is larger than the divisions of the rotative disc a
small circular arc is used, which is successively marked with numbers corresponding
to any desired number of total rotations of the disc, and which is moved through
one such division each time that a total rotation of the disc is made by a tooth on
the disc opposite the highest number. In this manner if the disc is divided into
100, and the numbers to be added together produce a total of, say, over 200, two
complete rotations of the disc will be made in effecting the addition, so that the
small circular are will be moved through two divisions indicating 200, and the
remaining portion of the total or summation of the numbers will be indicated in
the disc.
For adding together composite numbers, for example, pounds, shillings, and
pence, the instrument consists of three such sets of apparatus, one for the pounds,
another for the shillings, and another for the pence.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Darling in the Great Seal Patent Office on the 11th June
1880.
JOHN DARLING, of Glasgow, in the County of Lanark, North Britain,
APPARATUS FOR EFFECTING AND CHECKING THE ADDITION OF NUMBERS."
"AN
My said Invention relates to an instrument or apparatus for effecting and
checking the addition of figures or numbers, and consists of a rotative disc, which
is carried in or upon a flat plato or frame. The outer edge of this disc is notched
or indented, and opposite each notch or indent is a number of the series into
which the disc is divided, for example 50, 100, or other suitable number. Near to
the edge of the rotative disc is an arc, on which is a series of numbers from 1
progressing upwards to any desired number.
When it is required to add any numbers together the numbers are successively
read on the fixed arc, and a pointer is placed in the notch in the rotative disc
opposite each such number, by which pointer the rotative disc is turned round
until reaching a stop which is placed for checking its further rotation. The result
is read off' on the rotative disc, a portion of which is seen through an opening in
the plate by which it is partly covered. For the purpose of adding together
numbers whose total is larger than the divisions of the rotative disc a small
circular arc is used, which is successively marked with numbers corresponding to
any desired number of total rotations of the disc, and which is moved through one
such division each time that a total rotation of the disc is made by a tooth on the
disc opposite the highest number In this manner if the disc is divided into 100,
and the numbers to be added together produce a total of say over 200, two
complete rotations of the disc will be made in effecting the addition, so that the
small circular arc will be moved through two divisions indicating 200, and the
remaining portion of the total or summation of the numbers will be indicated on
the disc.
The instrument or apparatus may be used for adding together composite numbers,
such as pounds, shillings, and pence, as hereinafter described.
And in order that my Invention may be properly understood I will now
proceed to described a system, mode, or manner in or under which the same is or
may be used or carried into practical effect, reference being had to the accompanying
Drawing and to the letters and figures marked thereon.
I will describe my Invention with regard to an instrument or apparatus so
constructed or arranged according to my said Invention as that one disc or wheel of
the said apparatus is adapted to deal with additions amounting to 99, and another
disc is arranged in connection therewith so as to be moved through a portion of a
rotation at each complete rotation of the first named disc so as as to indicate the
number of times that the said first named disc has been rotated, and consequently
the hundreds in the calculation being made. Figure 1 of the accompanying
Drawing represents the face of the first named disc, which is marked A; Figure
represents the face of the second disc, which is marked B. The disc A has its
periphery divided into one hundred equal parts or divisions, at each of which is a
notch a. Upon the said disc is a circle a², also divided into one hundred equal
parts or divisions, each part being marked with numerals indicating from 1 to 99,
the first division being marked with two ciphers, and the numerals 1 to 9 being
each preceded by a cipher for reading them in connection with the indications of
the circle b² of the disc B, ns hereinafter described. The periphery of the disc B is
divided into one hundred equal parts or divisions and teeth b, and has upon it a
circle 6² divided into one hundred equal parts or divisions bearing numerals from
1 to 99, the first division being blank. In the said disc are slots b³, through which
the numerals of the circle a³, of the disc A, are seen when the two discs are placed

page_text: together centre to centre, as shewn in Figures 3 and 4, which respectively represent
a plan and a transverse section of the instrument or apparatus as arranged in its
casing or cover C. The said discs are secured to the said casing by a screw c
passed through the central holes in the said discs A and B, and screwed into a
boss c³, on the said casing, so that the said discs are capable of rotation on the said
screw c A pinion D turns upon a spindle d, secured to and projecting outside
the casing C, where it is provided with a milled head d². A spring catch e is
fastened to the casing C, which spring catch engages between the teeth b to prevent
the accidental movement of the disc B The head of the said catch e which
engages between the said teeth is bevilled so as to yield to the pressure of the
teeth when rotation is given to the said disc B by the pinion D.
In the casing C is a semicircular slot c², the edge of which is divided into fifty
equal divisions c³, corresponding to fifty divisions of the wheels A and B, these
divisions being marked with numerals from 1 to 50, as shewn. A slot c is made
in the said casing C, through which alot one division of such circles as contain the
requisite particulars are seen when making the required calculation.
I will now describe the method of using the instrument or apparatus, and for
this purpose I have shewn in Figures 5 to 9 portions of the instrument at the
slot c, shewing the indications of the various circles after certain calculations which
I will take as examples have been made. In these said Figures the divisions of
the various circles, which are shewn as appearing before the slot c³, are marked
with the respective letters with which the respective circles to which the said
divisions belong are marked in Figures 1 and 2. In Figure 3 the circles are shewn
at zero, that is to say, at the starting point, when the first division (viz., that
marked 0, 0,) of the circle a² of the disc A is before the slot c', and the first or
blank division of the circle be of the disc B is before slot c, and is seen through the
slot 63 of the disc B. Supposing that 47 and 29 are to be added together, a pointer
or other suitable instrument will be placed in the notch a of the disc A, which
appears at the slot c² opposite that of the divisions of the semicircle c³, which is
marked 47, and the said dise A will then by means of the said instrument be
moved through a partial rotation in the direction of the arrow in Figure 3 until
the said instrument comes against the stop formed by the end of the slot c², and the
said instrument will then be withdrawn and re-inserted in that notch a of the
disc A which appears at the slot c² opposite that division of the semicircle c³ which
is marked 29, and the said disc A will then again be moved through a partial
rotation in the direction of the arrow in Figure 3 until the said instrument comes
against the stop at the end of the said slot c. As the notches a and the divisions
of the circle a and of the semicircle c³ bear the same proportion to their respective
circles, the disc A will have moved during the first operation so that a number of
divisions of the circle a³ equal to the number of divisions of the semicircle c³
opposite which the wheel A was moved, that is to say, 47 divisions will have
passed before the slot c, and during the second operation the disc A will be moved
so that an additional number of divisions of the circle a³ equal to the number of
divisions of the semicircle c³ opposite which the wheel A was moved by this said
second operation will pass before the slot c, and consequently a total of 76 divisions
of the circle a will have passed before the said slot c, and the number 76 on the
circle a will appear before the said slot c* (as shewn in Figure 5), indicating the
result of the addition of the quantities 47 and 29; additional quantities may be
added to this amount, and after the disc A. has been moved through one complete
revolution, that is to say, when 100 is to be indicated before the slot c', the
projection as on the said disc A will move round the pinion D the extent of one
tooth, which will in turn move round the disc B through the extent of one tooth or
one hundredth of a revolution, so that the numeral ] on the circle b² will appear
before the slot c, and amounts between 100 and 200 will be indicated by the
operation of the disc A. as before described. At the next complete revolution of the
disc A the disc B will be moved through another one hundredth of a revolution,
and the numeral 2 on the circle 6ª will appear before the slot c³ and so on. The

page_text: disc B may be moved independently of the disc A by operating the pinion D by the
milled head d³ in order to add hundreds to the indication or to set the indication of
the instrument to any desired number.
Combined with the apparatus are shewn means for indicating the amounts in
pounds, shillings, and pence of any number of pence which may be indicated by the
division of the circles a and b before the slot c. Upon the circle a' of the disc A
are one hundred divisions, upon which are marked (in radial line with the respec-
tive divisions of the circle a³) in shillings and pence the respective money values of
the amounts of pence given by the quantities in the said respective divisions of the
circle a. These respective divisions of the circle a will appear before the slot c
so that the money value of the number of pence indicated by the division of the
circle a³, which is kept before the slot c', will at the same time appear through the
said slot upon the circle a, a slot f being made in the disc B through which
the divisions of the circle a' can be seen. Thus, in Figure 5, the division of the
circle at opposite the division of the circle a², marked 76, appears at the slot c', the
said division of the circle a being marked 6/4, being the money value of seventy
Six pence. Upon the said disc A is another circle as of one hundred divisions, each
containing successively the money value of the number of pence from 100 to 199,
so as when the circle 6 of the disc B is moved round one hundredth of a revolution
to indicate in combination with the circle a³ amounts from 100 to 199, as before
described, the slot g in the said disc B is then brought before the slot c, and through
it will be seen on the said divisions of the circle a³ the money value of the amount
of pence indicated by the said circles a² and 63, the part 6 of the disc B when the
said disc is so moved through one hundredth of a revolution covering the division
of the circle a, which could otherwise be seen through the slot c. As an example,
in Figure 6 are shewn the indications of the instrument when the circles a³ and b*
register 150, when the division of the circle a³ in radial line with the division of
the circle a³, marked 50, appears before the slot c, the said division being marked
12/6, being the money value of one hundred and fifty ponce. Upon the said disc
A is also another circle as of one hundred divisions, each containing successively the
money values of the number of pence from 200 to 299, so that when the circle 6 of
the disc B is moved round the second one hundredth of a revolution to indicate in
combination with the circle a² amounts from 200 to 299 the slot h in the said disc B
will be brought before the slot c, and through it will be seen on the said divisions
of the circle as the money value of the amount of pence indicated by the said circles
a and b, the part 67 of the disc B when the said disc is so moved through the
Becond one hundredth of a revolution covering the division of the circle us, and the
portion 68 of the disc B covering the division of the circle a', which would other-
wise be seen through the slot c. As an example, in Figure 7 are shewn the
indications of the instrument when the circles a² and 6 register 270, when the
division of the circle a in radial line with the division of the circle a³, marked 70,
appears before the slot ct, the said division being marked 22/6, being the money
value of two hundred and seventy pence. Upon the disc B is a circle 6º divided
into equal divisions each of one hundredth part of the circle, and upon it are succes-
sively marked the money values of hundreds of pence from 300 to 9900, that is to
say, in the division of the circle 6, which is in radial line with the division of the
circle b³, marked 3, is given the money value of 300 pence, and in the division of
the circle bo, which is in radial line with the division of the circle b³, marked 4, is
given the money value of 400 pence, and so on. In order to ascertain the money
value of quantities between the hundreds from 300 upwards the indications of the
circles a and b are added together, the divisions of the circle a* being visible
(when and after the disc B has been moved through three hundredths of a revolu-
tion) at the slot c through the slots 6' in the disc B.
As an example, in Figure 8 I have shewn the indications of the instrument when
the circles a3 and 6 register 500, that is to say, when the division marked 5 of the
circle b and the division marked 00 of the circle a² are before the slot ct, the blank
division of the circle at being before the said slot, and the division of the circle b³

page_text: marked with the money value of five hundred pence, namely, 21. 18. 8d. being
opposite the said slot c.
As a further example I have shewn in Figure 9 the indications of the instrument
when the circles a³ and 6 register 7179, that is to say, when the division of the
circle 6* marked 71 and the division of the circle a' marked 79 are before the Blot c'.
when the division of the circle 6º in radial line with the division of the circle be
marked 71 will be seen at the slot c, the said division of the circle b* being marked
with the money value of 7100 pence, viz., 291. 118 8d and the divisions of the circle a*
in radial line with the division of the circle a marked 79 will also be seen at
the slot c, the said division of the circle a being marked with the money value
of 79 pence, viz., 6/7. By adding together the two amounts thus seen a total
of 291. 188. 3d. is obtained, being the money value of seven thousand one hundred
and seventy nine pence.
The slot may be less or more than a semicircle, so that less or more than fifty
divisions or notches a appear thereat.
Although I have described my Invention with regard to an instrument having
two discs and two circles of figures divided into one hundred divisions for dealing
with numbers increasing by units on the one disc and by hundreds on the other
disc, yet it is to be understood the apparatus or instrument may be considerably
varied to enable it to be employed for the calculation of different quantities or
values without departing from the nature of my Invention. For example, one disc
(corresponding to the dise A) and divided into any requisite number of divisions
may be employed in combination with a slot (similar to the slot c³) divided into
any number of divisions for counting to small amounts, provided that the divisions
of the disc bear the same proportion to its circumference as the divisions of the
said slot bear to the circle of which the said slot forms part. The apparatus may
be provided with more than two discs to enable it to be employed for counting to
high numbers, that is to say, for example, another wheel or ring similar to that
marked B may be provided to be turned through a portion of a rotation at each
rotation of the disc B by a projection on the said disc B, in essentially the same
manner as the said disc B is rotated from the disc A, the said additional disc
bearing a circle of divisions marked with numerals which being brought before the
slot c, before (that is to the left hand of) the figures of the circles a and b, will
indicate tens and hundreds of thousands. The discs which are uppermost will of
course in any case be slotted in manner similar to that in which the disc B is slotted
at b and b, so as not to impede the view of the figures or indications on the disc
or discs beneath which it may be necessary to see. The divisions of the various
circles may also be varied to suit different requirements. The disc A might, for
example, be provided with a circle (a) divided into 112 equal parts representing
pounds avoirdupois, and the circle 6 of the disc B might then be used for indicating
hundredweights. In place of English money values being given upon the circles a*,
a, a, and b, the said circles may bear foreign money values, or values in English
or foreign weights or measures, or other values or signs, as may be convenient or
requisite to render the instrument or apparatus constructed or arranged according
to iny Invention applicable to the calculation of such special amounts, quantities,
or values, as it is or may be applicable to.
It will be understood that the apparatus may be employed for the subtraction of
numbers by inserting the pointer or other operating instrument into the notch a
of the disc A which is before the slot c³ at the part marked x, and moving the disc
in a direction the reverse of that shewn by the arrow in Figure 3 until the notch
with which the said instrument is engaged comes opposite that division of the
semicircle c³ which is marked with the number to be subtracted from the amount
previously indicated at the slot c.
Having now described and particularly ascertained the nature of my said Inven-
tion, and the system, mode, or manner, in or under which the same is or may be
used or practically carried into effect, I would observe in conclusion that I do not
Imit myself to the precise details herein described and illustrated, as the same may

page_text: (as before stated) be varied without departing from the nature of my said Invention,
but what I consider to be novel and original, and therefore claim as the Invention
secured to me by the hereinbefore in part recited Letters Patent is,―
An apparatus or instrument for effecting or checking the calculation or addition
of numbers, and indicating values, quantities, or amounts, constructed or arranged
essentially as herein before described with reference to the accompanying Drawings,
that is to say, an apparatus consisting of a disc or discs moveable in relation to a
proportional scale (such as that c³, Figure 3) for indicating calculations made by the
movement of the said disc or discs, whether such discs be divided or marked with
indications and values, quantities, or amounts, as shewn in the accompanying
Drawing, or be otherwise divided or marked with other indications or values,
quantities, or amounts, essentially as hereinbefore described.
In witness whereof, I, the said John Darling, have hereunto set my hand
and seal, this Ninth day of June, in the year of our Lord One thousand
eight hundred and eighty.
JOHN DARLING. (L.S.)