Year: 1888

page_text: Date of Application, 16th July, 1888
Complete Specification Left. 16th Apr., 1889
Complete Specification Accepted, 1st June, 1889
I THOMAS MUDD, of Hartlepool, in the County of Durham, Engineer, do hereby
declare the nature of this invention to be as follows:-
The object of the invention is to provide a slide rule or calculating instruments
which may be constructed of such a size and shape as to be applicable for the
pocket.
In carrying out the invention, a logarithmic slide rule is provided in the form of
a circle, with a central dial working within same, and with a pointer moving from a
centre as a marker of the various stages in the calculation. The whole may be made
in the form of a common watch with glass covering face, and the moving parts and
pointers actuated from the outside after the manner of the winding of a keyless
watch, or more pointers may be provided actuated by gear from the same thumb
screw or milled wheel, so that the one pointer moves at a greater or less rate than the
other. Thus, if one pointer moves twice as fast as another, the former (on a
logarithmic scale) will show the square of the number indicated by the latter. If
three times as fast, then the cube will be shown and so on.
These can be embodied in separate instruments, or included in the same, one being
on the reverse side of the watch-like instrument.
**
A pointer may also be formed to act as a vernier" for reading small quantities.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.

page_text: 1, THOMAS MUDD of Hartlepool, in the County of Durham, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
The object of this invention is to provide a slide rule or calculating instrument,
which may be constructed of such a size and shape as to be applicable for carrying in
the pocket.
In carrying out the invention, a logarithmic slide rule is provided in the form of
a circle, with a central dial working within same and with a pointer moving from a
centre as a marker of the various stages in the calculation. The whole may be made
in the form of a common watch with glass covering face, and the moving parts and
pointer actuated from the outside after the manner of the winding of a keyless watch.
Or more pointers may be provided actuated by gear from the same thumb screw
or milled wheel, so that the one pointer moves at a greater or less rate than the
other. Thus, if one pointer moves twice as fast as another, the former (on a
logarithmic scale) will show the square of the number indicated by the latter. If
three times as fast, then the cube will be shown, and so on.
These pointers can be embodied in separate instruments, or included in the same
one, being on the reverse side of the watch-like instrument.
Referring to the accompanying drawings
Figures 1 and 2 are elevations of the two sides of the instrument.
Figure 3 is a sectional elevation.
Figure 4 is a transverse sectional elevation.
The drawings are purposely drawn somewhat disproportionately in order to render
the action clearer.
Like reference numbers indicate corresponding parts in all the Figures.
In the outer case of the instrument (which may resemble the case of an ordinary
watch) is mounted the central dial or disc 1, which is revolvable within a fixed circle
or ring 2, placed around the same.
They scale marked on the adjacent edges of the parts 1 and 2 is, in this instance,
the ordinary logarithmic scale, similar to that on any ordinary slide rule.
The dise I may be moved around its axis by turning the milled wheel 4, which is
carried by a sleeve 5. This sleeve carries at its inner end a bevel wheel 6, which
gears with another bevel wheel 7 attached to the disc 1.
3 is a pointer or marker which may be turned around the
turning the milled head 8 which is attached to the spindle 9.
through the sleeve 5 and carries a bevel wheel 10, which gears
attached to the arbor of the said pointer 3. Although I have
axis of the disc, by
This spindle 9 passes
with a bevel wheel 11
shown and described
-

page_text: the pointer 3 as a radial pointer worked from the centre of the dial, I do not`hini
myself to that form and arrangement. For instance it might be loose and revolvable
in a groove around the case by hand.
The operation of this side of the instrument is similar to that of any ordinary
slide rule. but the scale being made in a circle, there is no necessity to shift from
end to end as with the straight rule; also the use of the marker 3 enables continuous
and complicated calculations to be performed without stopping to record intermediate
results.
The side marked as in. Figure 1 of the instrument, is suitable for multiplication
and. division. The side marked as in Figure 2, may be used for finding, at one
operation, the square or cube of a number, or the square root or cube root of a
number. 12 is a fixed disc marked with one scale exactly like that on the disc 1.
Over this disc two radial pointers or markers move. The inner marker 17 is
attached to a sleeve, to which are rigidly attached two bevel wheels 14 and 16.
These wheels 14 and 16 are separately actuated by two bevel pinions 13 and 15.
These pinions are carried upon the spindle 9 aforesaid, in such manner that, though
they may be moved longitudinally thereon when required, they always turn with it.
The pinion 13 may be put in or out of gear with the wheel 14 by means of a
simple clutch arrangement 20, 21, consisting of a pivotted elbow lever 20 which may
be actuated from outside the case, and which serves, by means of the rod 21, to shift
the pinion 13 along the spindle 9, and thus bring about the engagement or dis-
engagement of the said pinion with the wheel 14.
In a similar manner the pinion 15 may be put into or out of gear with the wheel 16
by clutch 22, 23. Any other suitable clutch, either spring actuated or otherwise, may
be employed.
The outer marker 19 is fixed to the spindle which carries the wheel 18, which is
always in gear with the wheel 10 aforesaid, being actuated by spindle 9 and milled
head 8. Other means for actuating the said pointers 17 and 19 may be employed
without departing from the scope of the invention. For instance, they may be moved
from the back of the case by any suitable device.
The ratio of wheel 14 and pinion 13 is exactly 2 to 1, and the ratio of wheel 16
and pinion 15 is exactly 3 to 1. The wheels 18 and 10 are equal.
When pinion 13 is in gear with wheel 14, the milled head 8 is turned, the
marker 17 will travel round it exactly half the speed of marker 19, and just as
multiplying a natural logarithm by 2 gives the logarithm of the square of the
original number, so the marker 19 will indicate the square of the number on the
scale, to which the marker 17 is sei. On the other hand, if a square root is required
to be extracted, the marker 17 will indicate the square root of the number on the
scale to which marker 19 is set.
In like manner, when pinion 15 is in gear-with wheel 16 (and pinion 13 is running
free) the marker 17 will, on the milled head 8 being turned, travel at one third the
speed of marker 19; the latter will therefore indicate the cubes of the figures to
which the marker 17 is set; or conversely, marker 17 will indicate the cube roots of
the figures to which marker-19 is set.
If a wheel and pinion of the ratio 4 to 1 be employed, then 4th powers and 4th
roots can be indicated, and so on, to any required powers and roots.
If desired, a pointer may be arranged as a vernier to assist in indicating small
quantities or dimensions.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what
15:-
1. A calculating instrument having a fixed circular scale and an adjacent movable
circular scale concentric therewith and rotatable by suitable mechanism, and either
with or without a marker or pointer applicable for indicating or preserving the
results of previous calculations, substantially as described.

page_text: 2. A calculating instrument having a fixed circular scale, two or more indicators or
pointers adapted to work over the same, means for actuating the said pointers
simultaneously, and mechanism for adjusting or altering the ratio of the speed of
the pointers, substantially as described and for the purposes set forth.
3. The combined pocket calculating instrument as a whole, constructed and
arranged substantially as shown and described, and for the purposes set forth.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool.
Patent Agents for the Applicant.