AN IMPROVED INSTRUMENT TO BE USED AS A SUBSTITUTE FOR THE ORDINARY SLIDE RULE
Year: 1876

page_text: LETTERS PATENT to Henry Edward Newton, of the Office for Patents, 66,
Chancery Lane, in the County of Middlesex, Civil Engineer, for the Invention
of "AN IMPROVED INSTRUMENT TO BE USED AS A SUBSTITUTE FOR THE
ORDINARY SLIDE RULE." A communication from abroad by Alexandre Emile
Marie Boucher, Agent Administrateur de la Société des Forges et Chantiers de
la Méditerranée, of Paris, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said Henry Edward Newton at
the Office of the Commissioners of Patents on the 7th November 1876.
HENRY EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer. "AN IMPROVED INSTRUMENT TO BE USED
AS A SUBSTITUTE FOR THE ORDINARY SLIDE RULE."
Notwithstanding the advantages obtained by the employment of the slide rule it
has not come into general use owing to the objection many persons have to carry
an instrument of such an awkward shape in the pocket.
The object of this Invention is to produce an equivalent for the ordinary slide
rule, which will obviate the disadvantage above stated. To this end the rule is
made circular, and consists of two rings placed concentrically and enclosed in a case
like a watch case.
The outer of the two rings is fixed to the case, but the inner ring is capable of
being turned round by means of a small toothed pinion, the teeth of which take
into teeth on the back of the ring. The pinion is mounted on a short shaft which
projects through a collar on the case, and is provided with a thumb screw by which
it may be turned. A ring is connected with the collar, so that a chain may be
attached thereto if desired.
The two rings are marked off with the usual lines and figures for the purpose of
working out calculations.
As a modification of the above the fixed ring may be dispensed with, and a fixed
pointer or index may be used, in which case a moveable pointer must also be
provided.
The central part of the case may be used to receive a mariner's compass, an
aneroid barometer, a thermometer, or other useful article.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Edward Newton in the Great Seal Patent Office on the 7th
May 1877.
HENRY EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer. "AN IMPROVED INSTRUMENT TO BE USED
AS A SUBSTITUTE FOR THE ORDINARY SLIDE RULE" A communication from abroad
by Alexandre Emile Marie Boucher, Agent Administrateur de la Société des Forges
et Chantiers de la Méditerranée, of Paris, in the Republic of France.
Notwithstanding the advantages obtained by the employment of the slide rule
it has not come into very general use owing to the objection many persons have to
carry in the pocket an instrument of such an awkward shape.
The object of this Invention is to produce an instrument equivalent to the ordinary
slide rule, which will obviate the disadvantage above stated. To this end the rule
or instrument is made circular, and consists of two rings or dies placed concen-
trically, and enclosed in a case like a watch case.
The outer of the two rings is fixed to the case, but the inner ring is capable of
being turned round by means of a small toothed pinion, the teeth of which take
into teeth on the back of the ring. The pinion is mounted on a short shaft which
projects through a collar on the case, and is provided with a thumb nut or milled
head, by which it may be turned. A ring loop or pendant is connected with the
collar, so that the instrument may be suspended by or from a chain which may be
attached thereto if desired.
The two rings are marked off with the usual lines or divisions and figures for the
purpose of working out calculations as with an ordinary slide rule.
As a modification of the above the fixed ring may be dispensed with, and a
fixed pointer or index may be used, in which case a moveable pointer inust also be
provided.
The central part of the case may be used to receive a mariner's compass, an
aneroid barometer, a thermometer, or other useful instrument.
In the accompanying Drawing Figures 1 and 2, Sheet I., represent back and
front views of the instrument, shewing the two faces, the apparatus being drawn full
size; Fig. 3 is an edge view of the same.
Fig. 4 is a longitudinal vertical section of the instrument drawn upon an
enlarged scale, and Fig. 5 is a transverse section taken in the line 1, 2, 3, of Fig. 4.
These Figures clearly shew the internal arrangement of the mechanism, and the
mode of actuating the several parts.
The instrument is enclosed within a metal case like a watch case, and is provided
with two dials, the fixed one of which serves for trigonometrical calculations, and is
very carefully secured in a rebate made in the circular frame or periphery of the
metal case. The other or moveable dial serves for arithmetical calculations, and is
secured by two screws a, u, upon a flat wheel D, which is actuated by a pinion E
fixed upon the shaft C, the head of which is enclosed within the ring or pendant
of the instrument. The button or milled head A is at the outer end of a shaft A, F,
upon which is fixed the pinion F which serves to actuate the pointers or needles B
and I (Figures 1, 2, and 5) fixed upon the pivot H, which carries the wheel G in
gear with the pinion F. Upon the edge of the case (which encloses the moveable
dial) is fixed a small index or pointer K. The boss L, Figures 4 and 5, supports
the wheel of the moveable dial in place, and serves as a pivot for the same.
very accurately fitted, and it is moreover held in place by the inner ends of the
shafts A, F, and C, E, which project into it after passing through the ring M at the 5
middle of the casing. The shafts A, F, and C, E, are kept in their place by the
screws V and V, which pass through the casing and enter circular grooves made
(for the purpose) in these shafts. The two needles or pointers B and I are very
accurately fixed upon their common pivot H in the same vertical plane. The dials
are covered with glasses which are fitted and held in place like the glasses of 5
ordinary watches.
It is

page_text: In order to use the arithmetical dial of the instrument for "addition" the exterior
circle is used:-Bring the first number under the index, follow with the needle
the 0 of the dial, then bring the second number under the needle, and the index will
point out the sum.
For "subtraction" the exterior circle is also used:-Bring the greatest number
under the index, carry the needle over to the smaller, and bring the 0 under the
needle, the index will indicate the remainder.
For "multiplication" the interior circle is used:-Bring the first factor under the
index, follow the 0 with the needle, bring the second factor under the needle, and the
index will point to the product.
For "division" the interior circle is used:-Bring the dividend under the index,
carry the needle over the divisor, and bring back the 0 under the needle, the index
will point to the quotient.
For "proportion" the interior circle is also used:-As the index and the
needle will indicate the two terms of a ratio or proportion, all the numbers which
are brought under these points will be on the same proportion or ratio to each
other.
For "logarithms," upon bringing a given number upon the interior circle under
the index, the latter will indicate on the exterior circle the decimal part of the
logarithm of this number.
For "powers" and "roots," take the logarithm of the number, multiply it or
divide it by the exponent, according as a power or a root may be required, and
bring the product or the quotient (taken upon the outer circle) under the index,
which will point out on the inner circle the power or the root required.
To use the trigonometrical dial:-Bring the needle of this dial over the angle of
which the sine or tangent is required, and read upon the other dial (indicated by
the needle) the natural trigonometrical line upon the inner circle or its logarithm
upon the outer circle.
The Figures in Sheet II. represent different modifications of the improved
calculating circle constructed of larger dimensions for use in offices, workshops, and
elsewhere. The increased size admits of enlarging the field of operations, and of
obtaining a greater degree of accuracy in the calculations by introducing an increased
number of concentric circles. By these means a calculating machine of moderate
dimensions will be found to answer all the purposes of a slide rule or calculating rule
of from five to eight feet, and even twenty-five feet in length. Such a development
of the logarithmic scale upon which all numbers from one to ten thousand may be
inscribed would take the place of a table of logarithms with five places of decimals;
Fig. 7 partly shows this.
Instead of developing the logarithmic scale upon several concentric circles it may
perhaps be considered preferable to construct it on a spiral (or convolute) made of
the same number of spirals or curves as there are circles in the other arrangement;
the spiral arrangement is shewn at Fig. 9.
Figures 6 and 7 shew in section and in plan one of the modes of constructing
calculating machines for office use; A is a fixed dial (in cardboard, brass, or any
other suitable material) secured by screws or otherwise upon the wooden support K;
B is the turning disc or glass carrying a black radial line; C, C, are round copper
discs or washers rivetted or otherwise secured to the glass disc; D is a button or stud
rivetted to the same disc; E is a button or stud screwed on to the central pivot G;
F is a disc or washer fastened by screws to the disc C; G is the pivot or centre of
motion of the disc and of the needle; its head is countersunk, and fixed by screws
to the block K; a button H is rivetted to the needle I, which is made of sheet
brass;
L is a brass circle attached by screws to the wooden block K. It is by
moving the disc B and the needle I that the desired results are obtained. For
multiplication (for example) the radial line of the disc B being at 0 of the dial, the
needle I is brought over one of the factors, then the black radial line of the disc B
is brought over the other factor. In this second motion the needle is brought over
the product. When the operator takes hold of the button H in order to turn the

page_text: needle the glass disc is held in place (should it be necessary to do so,) as is sometimes
the case when the friction is too great, but when the operator moves round the
dise B he leaves go of the button H, and then the needle is free to follow the move-
ment of the disc.
As a modification these instruments may be so constructed that the dial will be
moveable as in the pocket instruments, the only difference will be that the mechanism
will be a little more complicated.
It will be evident that these calculating circles (for office use) may be made of any
dimensions, and that their mechanism and the materials of which they are con-
structed may be varied. It will be understood then that with this new calculating
circle (whatever may be its dimensions) all the operations that can be done with the
old slide rule may be carried out with facility by means of the improved machine.
In fact it will do more, because the circle which is divided in equal parts and surrounds
the logarithmic scale of numbers may be used also for adding and subtracting,
which cannot be done with the old rule. With this latter it is necessary (when the
solution of a problem requires several operations) to note (at least by memory) the
partial results obtained, and to consider them as new factors in place of others of
which they were the products. The use of the calculating circle will dispense with
the necessity of having to keep account of these successive partial results. The
central part of the box being empty the maker may easily place there a watch on
the side of the trigonometrical dial. This addition may be made very easily by
slightly modifying the form of the central pivot. This empty space may also be
utilized to receive a compass, an aneroid barometer, or a thermometer. In fact
the calculating circle may be adapted to the round handle of a walking stick
or umbrella by simply modifying the mode of moving the disc and the needle.
Having now described the improved instrument which is to be used as a sub-
stitute for the ordinary slide rule, and having explained the manner of carrying the
same into effect, as communicated to me by my foreign correspondent, I claim as
the Invention secured to me by Letters Patent as aforesaid, constructing calculating
instruments as herein set forth as a substitute for the ordinary slide rule, and con-
sisting of a combination of fixed and moveable circles, discs, or dials, with fixed
and moveable indexes, pointers, and needles, as above shewn and described.
In witness whereof, I, the said Henry Edward Newton, have hereunto set my
hand and seal, the Seventh day of May, in the year of our Lord One
thousand eight hundred and seventy-seven.
H. E. NEWTON. (L.S.)