US2646220A - Arithmetical device for writing instruments - Google Patents
Arithmetical device for writing instruments Download PDFInfo
- Publication number
- US2646220A US2646220A US295062A US29506252A US2646220A US 2646220 A US2646220 A US 2646220A US 295062 A US295062 A US 295062A US 29506252 A US29506252 A US 29506252A US 2646220 A US2646220 A US 2646220A
- Authority
- US
- United States
- Prior art keywords
- barrel
- casing
- numbers
- openings
- rows
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B43—WRITING OR DRAWING IMPLEMENTS; BUREAU ACCESSORIES
- B43K—IMPLEMENTS FOR WRITING OR DRAWING
- B43K29/00—Combinations of writing implements with other articles
- B43K29/08—Combinations of writing implements with other articles with measuring, computing or indicating devices
- B43K29/093—Combinations of writing implements with other articles with measuring, computing or indicating devices with calculators
Definitions
- My invention relates generally to writing ⁇ 1nstruments such as pens and pencils, and more particularly to arithmetical devices as combinedv therewith.
- An object of my invention is to provide an arithmetical device particularly adapted, although not necessarily, for use by children and students in the study of elementary arithmetic, and which in its association with a writing instrument enables the answers to problems in the various elementary arithmetic processes to be directly read with the utmost ease and dispatch following a simple and quick adjustment of the device, all to the end of expediting the mathematical education of the user by providing a convenient and entertaining method of obtaining the answers to a wide range of arithmetic problems.
- Another object of my invention is to provide an arithmetical device for writing instruments of the above described character which is of simple, compact and inexpensive construction enabling the device to be embodied in a pen or pencil at a slight additional cost.
- Figure 1 is a view of a writing instrument in side elevation, partly in section, with one form of arithmetical device embodying myinventicn applied thereto, and showing one position of adjustment of the device; Y
- Figure 2 is a view similar to Figure 1 and showing another position of adjustment of the device
- Figure 3 is a view in side elevation showing the body of the writing instrument with the casing and number sheet of the device removed;
- Figure 4 is an enlarged longitudinal axial sectional view of the writing instrument
- Figures 5 and 6 are transverse sectional Views taken respectively on the lines 5 5 and S-S of Figure 4.
- Figure 7 is a plan view of a typical number sheet embodied in my invention.
- a writing instrument such as a ball pen which comprises a body B and a cap C therefor constructed of plastic, metal or other suitable material.
- the ,bodyB is composed of one element in the form of an open-ended cylin- 2 drical barrel or tube l!) externally screw threaded at one end as shown'at H ( Figurel) to re-' movably receive internal screw threads I2 of a tapered neck I3.
- a conventional ball pen unit having the usualwriting ball i4 at its tip end l5 and an ink supply tube i6 is removably fitted in the neck by means of an enlarged intermediate screw threaded portion Il which screws into a threaded bore i8 in the neck, so as torigidly support the ball pen unit U with the ball l 4 protruding slightly from the neck and the tube I6 projecting co axially into the barrel lil.
- the barrel li! is slightly reduced in diameter as indicated at E9 to receive a number sheet S which is wrapped around the barrel and is permanently fixed thereto by a suitable adhesive.
- the other element of the body B is mounted for rotation and axial adjustment on the barrel i@ so as to bear only on the full vdiameter thereof beyond the ends of the number sheet S.
- the casing 20 is provided adjacent to its left handfend with VAa single control opening or window 2l. Between the opening 2
- the grooves 25 and Z6 are connected at one point only by a groove 2l extending longitudinally of the barrel so as to provide communication between the grooves 25 vand 26 forfan internal projection 23 in the form of a pin or teat on the inside cf the casing.
- the projection 28 is adapted'to travel in the groove 25 or 26 upon rotation of the casing on the barrel and according as the casing is. ad-
- the number sheet S is provided Withrows of numerals extending o circumferentially and longitudinally of the barrel. 'I'he relationships and Values of the number tables on the sheet are such that the answers to problems in addition and subtraction can be directly read by use of the control opening 2
- alternate circumferential rows 30 of numbers on the sheet S which constitute one table may be printed in black, whereas the other alternate rows 3
- the numbers of these two tables will appear in the openings 22 according as the casing is axially adjusted on the barrel to one'or the other of the extreme positions shown in Figures 1 and 2.
- Two circumferential rows 32 and 33 of control numbers are arranged at the left hand end of the aforesaid tables and are printed in black and red, respectively, for co-action with the table of the same color, and are arranged to appear in the control opening 2
- the barrel l@ is rotated until the projection 28 is alined with the groove2 ⁇
- the casing 29 may now be adjusted axially on the barrel to the position shown in Figure l.
- the barrel is now rotated until the number Bappears in the control opening 2
- the product 4G can now be read directly in that one of the openings 22 having the indicated value of 8.
- one table or another on the sheet S may be utilized in conjunction with the openings 2
- a suitable-magnifier 35 ( Figure 4) may be applied to the casing 20 so as to magnify much smaller print on the tables to an easily readable size and thus permit the range of the tables to be greatly increased in the small space provided on the barrel I0.
- an arithmetical device comprising: a barrel having thereon a plurality of arithmetic tables each composed of circumierentially extending rows of numbers, with the rows of one table alternating with the rows of the other table along the length of the barrel; said barrel having rows of circuinierentially extending control numbers, one row for each of said tables; a casing having a series of openings with accompanying indicia designating predetermined number values for said openings; said casing having a control opening; means mounting and conning said casing on said barrel in any one of a plurality of longitudinally spaced positions for relative rotation; and means co-acting with the last means to -nable relative translational adjustment of said sing and barrel from one to another oi said ositions to be eiected in a predetermined posi- J tion or relative rotational adjustment oi" the casing and barrel to accordingly dispose the numbers of one table or another for viewing in said series of openings and the numbers of
- an arithmetical device comprising: a barrel having thereon a plurality of arithmetic tables each composed of circumierentially extending rows of numbers, with the rows of one table alterhating with the rows of another table along the length of the barrel; said barrel having rows of circumferentially extending control numbers, one row for each of said tables; a casing having a series of openings with accompanying indicia designating predetermined number values for said openings; said casing having a control opening; said barrel having a plurality of annular grooves one for each of said tables and spaced apart along the length of the barrel, and a transfer groove connecting said annular grooves; said casing having a projection working in said annular grooves and passable through said transier groove from one annular groove to another to accordingly dispose the numbers of one table or another for viewing in said series oi openings, and the numbers of one or another of said rows oi control numbers for viewing in said control opening upon relative rotational adjustment oi the casing and
- the inner one ofsaid elements having a plurality of arithmetic tables each composed of circumferentially extending rows of numbers, with the rows of one table alternating with the rows of the other table along the length of such element; said inner element having rows of circumferentially extending control numbers one row for each of said tables; the outer one of said elements having a series of openings with accompanying indicia designating predetermined number values for said openings; said outer element having a control opening; one of said elements having a plurality of annular grooves one for each of said tables and spaced apart along the length of said element, and a transfer groove connecting said annular grooves; the other of said elements having a projection Working in said annular grooves and passable through said transfer groove from one annular groove to the other to accordingly dispose the numbers of one vtable or the other for viewing in Vsaid series of openings, and the numbers of one or the other of said rows of control numbers for viewing in said control opening upon relative
Landscapes
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Toys (AREA)
Description
July 21, 1953 J. wElsER ARITHMETICAL DEVICE FOR WRITING INSTRUMENTS Filed June 25, 1952 N VEN TOR.
.4 TTOE/I/ E Y |4425 Ien 26 |76 27] 26h70 21 |87 zalm.
\3/ JACK Welse/a /LLaCn/u.
S\OI
Patented July 21, 1953 ARITHMETICAL DEVICEv Fon WRITING INSTRUMENTS 1 1 'n JI ack Weiser, Los Angeles, Calif. Application June 23, 1952, Serial No. 295,062
4 Claims.
l My invention relates generally to writing `1nstruments such as pens and pencils, and more particularly to arithmetical devices as combinedv therewith. f
An object of my invention is to provide an arithmetical device particularly adapted, although not necessarily, for use by children and students in the study of elementary arithmetic, and which in its association with a writing instrument enables the answers to problems in the various elementary arithmetic processes to be directly read with the utmost ease and dispatch following a simple and quick adjustment of the device, all to the end of expediting the mathematical education of the user by providing a convenient and entertaining method of obtaining the answers to a wide range of arithmetic problems.
Another object of my invention is to provide an arithmetical device for writing instruments of the above described character which is of simple, compact and inexpensive construction enabling the device to be embodied in a pen or pencil at a slight additional cost.
With these and other objects in View, my invention resides in the combinations, arrangements and functional relationships of elements as set forth in the following specification and particularly pointed out in the appended claims.
In the accompanying drawings,
Figure 1 is a view of a writing instrument in side elevation, partly in section, with one form of arithmetical device embodying myinventicn applied thereto, and showing one position of adjustment of the device; Y
Figure 2 is a view similar to Figure 1 and showing another position of adjustment of the device;
Figure 3 is a view in side elevation showing the body of the writing instrument with the casing and number sheet of the device removed;
Figure 4 is an enlarged longitudinal axial sectional view of the writing instrument;
Figures 5 and 6 are transverse sectional Views taken respectively on the lines 5 5 and S-S of Figure 4; and
Figure 7 is a plan view of a typical number sheet embodied in my invention.
Referring specically to the drawings, my invention is shown for the purpose of illustration combined with a writing instrument such as a ball pen which comprises a body B and a cap C therefor constructed of plastic, metal or other suitable material. The ,bodyB is composed of one element in the form of an open-ended cylin- 2 drical barrel or tube l!) externally screw threaded at one end as shown'at H (Figurel) to re-' movably receive internal screw threads I2 of a tapered neck I3. f A conventional ball pen unit having the usualwriting ball i4 at its tip end l5 and an ink supply tube i6 is removably fitted in the neck by means of an enlarged intermediate screw threaded portion Il which screws into a threaded bore i8 in the neck, so as torigidly support the ball pen unit U with the ball l 4 protruding slightly from the neck and the tube I6 projecting co axially into the barrel lil. l For the major portion of its length the barrel li! is slightly reduced in diameter as indicated at E9 to receive a number sheet S which is wrapped around the barrel and is permanently fixed thereto by a suitable adhesive. Mounted for rotation and axial adjustment on the barrel i@ so as to bear only on the full vdiameter thereof beyond the ends of the number sheet S is the other element of the body B in the form of a cylindrical casing or tube 23, one end of which closes the corresponding end of the barrel.
As shown in Figures l and 2, the casing 20 is provided adjacent to its left handfend with VAa single control opening or window 2l. Between the opening 2| and the right hand end of the casing, same is provided with a row of openings 22 uniformly spaced apart andv consecutively numbered l, 2, 3, 4, 5, S, l, 8, 9, le, il and l2 so as to have these definite values vfor co-action with thencontrol opening 2l in a manner to be later described.
Adjacent to the neck i3 and covered by the casing 2U are spaced annular grooves 25 and 26. The grooves 25 and Z6 are connected at one point only by a groove 2l extending longitudinally of the barrel so as to provide communication between the grooves 25 vand 26 forfan internal projection 23 in the form of a pin or teat on the inside cf the casing.
The projection 28 is adapted'to travel in the groove 25 or 26 upon rotation of the casing on the barrel and according as the casing is. ad-
justed longitudinally on the barrel to occupy either the extreme position shown in Figure l or the extreme position shown in Figures 2 and 4. It will thus be clear that the casing 2,0 is permanently mounted on the barrel l0 by the projection 28 and the grooves 25, 26 and 2l, for
rotational adjustment in either of two selected positions of axial adjustment. ,l
In the present instance the number sheet S is provided Withrows of numerals extending o circumferentially and longitudinally of the barrel. 'I'he relationships and Values of the number tables on the sheet are such that the answers to problems in addition and subtraction can be directly read by use of the control opening 2| and the numbered openings 22 with the casing 2D axially adjusted on the barrel I0 to the position shown in Figure 2, whereas the answers" to problems in multiplication and division can be directly read by the use of these openings with the casing 2U adjusted axially on the barrel to the position shown in Figure l.
For this purpose alternate circumferential rows 30 of numbers on the sheet S which constitute one table, may be printed in black, whereas the other alternate rows 3| of numbers on the sheet which constitute a second table, may be printed in red. The numbers of these two tables will appear in the openings 22 according as the casing is axially adjusted on the barrel to one'or the other of the extreme positions shown in Figures 1 and 2.
Two circumferential rows 32 and 33 of control numbers are arranged at the left hand end of the aforesaid tables and are printed in black and red, respectively, for co-action with the table of the same color, and are arranged to appear in the control opening 2| according as numbers of the table of corresponding'color appear in the openings 22.
To indicate the necessary axial setting of the casing 28 for one type of problem or another, plus and minus signs are associated with the legend Black and a direction indicating arrow for problems in additions and subtraction, whereas multiplication and division signs are associated with the legend Red and a direction indicating arrow for problems in multiplication and'division, all of which is suitably scribed or imprinted on the casing as shown in Figures l and. 2.
In operation, let it be assumed that the casing 2|] has` been axially adjusted to the position shown in Figure 2 for the reading of answers to problems in addition and subtraction which utilize the black printed table and control numbers of the number sheet, For example, to 3 to 9, the barrel i is rotated until the number 3 appears in the opening 2| as shown in Figure 2.
The sum'12 of 3 and 9 can be read directly in r that one of the openings 22 having the indicated value of 9.
To subtract 3 from 12, the process is reversed by merely reading as the answer the indicated value 9 of the opening 22 in which the number 12 appears.
For the reading of answers to problems in multiplication and division, the barrel l@ is rotated until the projection 28 is alined with the groove2`| which may be when the series of numbers to I2 of either the black or red table appear in the openings 22. The casing 29 may now be adjusted axially on the barrel to the position shown in Figure l. For example, to multiply and 8, the barrel is now rotated until the number Bappears in the control opening 2|. The product 4G can now be read directly in that one of the openings 22 having the indicated value of 8.
To divide 4D by 5, this process is reversed by merely reading as the answer the indicated value 8 of the opening 22 in which the number i appears.
From the'foregoing description it will be evident'that otherproblems such as square root and cube root can be answered with equal ease and dispatch by the use of different tables on the number sheet S, and that a greater range can be obtained by enlarged tables.
Furthermore it will be manifest that by a simple relative axial adjustment of the barrel and casing, one table or another on the sheet S may be utilized in conjunction with the openings 2| and 22 so as to provide for a maximum range of problems and answers consistent with the compactness of a writing instrument such as a pen or pencil.
It will be understood that if desired, a suitable-magnifier 35 (Figure 4) may be applied to the casing 20 so as to magnify much smaller print on the tables to an easily readable size and thus permit the range of the tables to be greatly increased in the small space provided on the barrel I0.
claim:
l. In an instrument of the class described, an arithmetical device comprising: a barrel having thereon a plurality of arithmetic tables each composed of circumierentially extending rows of numbers, with the rows of one table alternating with the rows of the other table along the length of the barrel; said barrel having rows of circuinierentially extending control numbers, one row for each of said tables; a casing having a series of openings with accompanying indicia designating predetermined number values for said openings; said casing having a control opening; means mounting and conning said casing on said barrel in any one of a plurality of longitudinally spaced positions for relative rotation; and means co-acting with the last means to -nable relative translational adjustment of said sing and barrel from one to another oi said ositions to be eiected in a predetermined posi- J tion or relative rotational adjustment oi" the casing and barrel to accordingly dispose the numbers of one table or another for viewing in said series of openings and the numbers of one or another of said rows oi control numbers for viewing in said control opening upon relative rotational adjustment of the casing and barrel.
2. In an instrument of the class described, an arithmetical device comprising: a barrel having thereon a plurality of arithmetic tables each composed of circumierentially extending rows of numbers, with the rows of one table alterhating with the rows of another table along the length of the barrel; said barrel having rows of circumferentially extending control numbers, one row for each of said tables; a casing having a series of openings with accompanying indicia designating predetermined number values for said openings; said casing having a control opening; said barrel having a plurality of annular grooves one for each of said tables and spaced apart along the length of the barrel, and a transfer groove connecting said annular grooves; said casing having a projection working in said annular grooves and passable through said transier groove from one annular groove to another to accordingly dispose the numbers of one table or another for viewing in said series oi openings, and the numbers of one or another of said rows oi control numbers for viewing in said control opening upon relative rotational adjustment oi the casing and barrel.
3. In an instrument of the class described, two elements arranged in telescoped relation; the inner one of said elements having a plurality of arithmetic tables each composed oi circumfertively connecting and confining said elements in any one of a plurality of longitudinally spaced positions for relative rotary adjustment; and means co-acting with the last means to enable relative longitudinal adjustment of said elements from any one of said positions to another to be effected in a predetermined position of relative rotational adjustment of the elements to accordingly dispose the numbers of one table or the other for viewing in said series of openings, and the numbers of one or the other of said rows of control numbers for viewing in said control opening upon relative rotational adjustment of said elements.
4. In an'instrument of the class described, two elements arranged in telescoped relation; the inner one ofsaid elements having a plurality of arithmetic tables each composed of circumferentially extending rows of numbers, with the rows of one table alternating with the rows of the other table along the length of such element; said inner element having rows of circumferentially extending control numbers one row for each of said tables; the outer one of said elements having a series of openings with accompanying indicia designating predetermined number values for said openings; said outer element having a control opening; one of said elements having a plurality of annular grooves one for each of said tables and spaced apart along the length of said element, and a transfer groove connecting said annular grooves; the other of said elements having a projection Working in said annular grooves and passable through said transfer groove from one annular groove to the other to accordingly dispose the numbers of one vtable or the other for viewing in Vsaid series of openings, and the numbers of one or the other of said rows of control numbers for viewing in said control opening upon relative rotational adjustment of said elements.
JACK WEISER.
References Cited inthe le of this patent UNITED STATES PATENTS Number Name Date 613,432 Szenhak Nov. 1, 1898 924,406 Walker June 8, 1909 1,161,381 Duffy Nov. 23, 1915 1,161,685 James Nov. 23, 1915 1,720,499 Walker July 9, 1929 1,732,983 Orchard Oct. 22, 1929 2,158,431 Sanders May 16, 1939 FOREIGN PATENTS Number Country Date 359,889 Italy June 7, 1938 529,555 Great Britain Nov. 22, 1940
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US295062A US2646220A (en) | 1952-06-23 | 1952-06-23 | Arithmetical device for writing instruments |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US295062A US2646220A (en) | 1952-06-23 | 1952-06-23 | Arithmetical device for writing instruments |
Publications (1)
Publication Number | Publication Date |
---|---|
US2646220A true US2646220A (en) | 1953-07-21 |
Family
ID=23136055
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US295062A Expired - Lifetime US2646220A (en) | 1952-06-23 | 1952-06-23 | Arithmetical device for writing instruments |
Country Status (1)
Country | Link |
---|---|
US (1) | US2646220A (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2777636A (en) * | 1953-09-08 | 1957-01-15 | Weiser Jack | Mathematical device for writing instruments |
US2908501A (en) * | 1955-04-28 | 1959-10-13 | Jasper M Rowland | Stock market game |
US5028764A (en) * | 1990-05-22 | 1991-07-02 | Roy Kuhlengel | Calculating instrument and method therefor |
US6742953B2 (en) | 2002-01-24 | 2004-06-01 | Bic Corporation | Writing instrument with display window |
US20050079002A1 (en) * | 2003-10-10 | 2005-04-14 | Sun Coast Merchandising Corp. | Writing pen that calculates body mass index |
US10388174B2 (en) | 2014-02-04 | 2019-08-20 | Oswaldo Angel | Writing instrument teaching system |
US20230294447A1 (en) * | 2022-03-17 | 2023-09-21 | Micro Co., Ltd. | Writing instrument having color indication-changeable grip |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US613432A (en) * | 1898-11-01 | Stanislas szenhak | ||
US924406A (en) * | 1908-06-06 | 1909-06-08 | Alexander Walker | Pencil-case and other cylinder. |
US1161381A (en) * | 1915-03-09 | 1915-11-23 | Charles Hugh Duffy | Calculator. |
US1161685A (en) * | 1915-02-19 | 1915-11-23 | Stephen J James | Educational appliance. |
US1720499A (en) * | 1926-07-01 | 1929-07-09 | Walker William | Educational computing device |
US1732983A (en) * | 1929-10-22 | Henry ben orchard | ||
US2158431A (en) * | 1937-10-18 | 1939-05-16 | Sanders Eli | Pencil attachment |
GB529555A (en) * | 1939-06-03 | 1940-11-22 | Louis William Johnstone | Improved ready reckoner device |
-
1952
- 1952-06-23 US US295062A patent/US2646220A/en not_active Expired - Lifetime
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US613432A (en) * | 1898-11-01 | Stanislas szenhak | ||
US1732983A (en) * | 1929-10-22 | Henry ben orchard | ||
US924406A (en) * | 1908-06-06 | 1909-06-08 | Alexander Walker | Pencil-case and other cylinder. |
US1161685A (en) * | 1915-02-19 | 1915-11-23 | Stephen J James | Educational appliance. |
US1161381A (en) * | 1915-03-09 | 1915-11-23 | Charles Hugh Duffy | Calculator. |
US1720499A (en) * | 1926-07-01 | 1929-07-09 | Walker William | Educational computing device |
US2158431A (en) * | 1937-10-18 | 1939-05-16 | Sanders Eli | Pencil attachment |
GB529555A (en) * | 1939-06-03 | 1940-11-22 | Louis William Johnstone | Improved ready reckoner device |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2777636A (en) * | 1953-09-08 | 1957-01-15 | Weiser Jack | Mathematical device for writing instruments |
US2908501A (en) * | 1955-04-28 | 1959-10-13 | Jasper M Rowland | Stock market game |
US5028764A (en) * | 1990-05-22 | 1991-07-02 | Roy Kuhlengel | Calculating instrument and method therefor |
US6742953B2 (en) | 2002-01-24 | 2004-06-01 | Bic Corporation | Writing instrument with display window |
US20050079002A1 (en) * | 2003-10-10 | 2005-04-14 | Sun Coast Merchandising Corp. | Writing pen that calculates body mass index |
US6890117B2 (en) * | 2003-10-10 | 2005-05-10 | Sun Coast Merchandise Corp | Writing pen that calculates body mass index |
US20060051156A1 (en) * | 2003-10-10 | 2006-03-09 | Sun Coast Merchandising Corp. | Calculating pen |
US7033102B2 (en) * | 2003-10-10 | 2006-04-25 | Suncoast Merchandise Corporation | Calculating pen |
US10388174B2 (en) | 2014-02-04 | 2019-08-20 | Oswaldo Angel | Writing instrument teaching system |
US20230294447A1 (en) * | 2022-03-17 | 2023-09-21 | Micro Co., Ltd. | Writing instrument having color indication-changeable grip |
US11845298B2 (en) * | 2022-03-17 | 2023-12-19 | Micro Co., Ltd. | Writing instrument having color indication-changeable grip |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2646220A (en) | Arithmetical device for writing instruments | |
US5149269A (en) | Manual teaching calculator | |
CN106515280A (en) | Universal compass intelligent drawing template | |
US2777636A (en) | Mathematical device for writing instruments | |
US2124550A (en) | Measuring instrument | |
US2158431A (en) | Pencil attachment | |
US3204344A (en) | Apparatus for teaching division by fractions | |
US3164906A (en) | Multiple pen combination | |
US1720499A (en) | Educational computing device | |
US3064888A (en) | Counting marker | |
US2262818A (en) | Device for pencils or the like | |
US2191662A (en) | Informative barrel for pencils, pens, or the like | |
US2785488A (en) | Pocket record device | |
US2526408A (en) | Cylindrical slide rule | |
US4207695A (en) | Mechanical writing instrument | |
US3365819A (en) | Education device | |
US3147915A (en) | Calculator | |
US3770193A (en) | Scoring device and counter therefor | |
US2503007A (en) | Mechanical pencil of the selective plural instrument type | |
US3314602A (en) | Gas mileage calculator | |
US2174440A (en) | Convertible pencil | |
US2922234A (en) | Educational aid for teaching reading | |
US2137630A (en) | Slide rule | |
ES234796U (en) | Variable numerical selection apparatus | |
US1288448A (en) | Mechanical calculator. |