Jaap's Mechanical Calculators Page

Comptometer

Comptometer Model E Comptometer Model J Comptometer Super Totalizer Comptometer Super Totalizer


Introduction
Calculation
"Controlled-Key" mechanism
Videos
Comptometer Simulator
Models
My Model E Comptometer
My Model J Comptometer
Super Totalizer
My Super Totalizers
Books and Manuals
Tables
Comptometer News magazine
Advertisements, Booklets, Leaflets, and Letters
Newspaper Articles
Paraphernalia
Patents
Links


The Comptometer is a mechanical calculation machine. It was invented Dorr E. Felt, and made by the Felt & Tarrant company in Chicago, USA. Felt gave a lecture about the history of mechanical calculators, which was published in 1916, and in it he briefly mentions how he came to make the first prototype of the machine in 1885. Its various models were in production from 1888 to 1961, peaking during the 1930s.

The "shoebox" case of the most common models is made of copper plated steel that is painted brown. Any Comptometers that seem to be made of shiny copper have had their original paint stripped or polished away.

The keyboard usually consists of 8, 10 or 12 columns. Each column has 9 buttons numbered 1 to 9 from nearest to furthest. To help with touch-typing, the tops of the even-numbered keys are almost flat, while the odd-numbered keys are concave.

In front of the keyboard there is a register. It is a row of small round windows through which you can see the digits of the calculation result. There is one more window/digit than there are columns of keys.

A top plate of the case extends some distance beyond the keyboard, and onto this is attached a chromed plate that bears the "Felt & Tarrant" name.


Calculation

The Comptometer is a direct adding machine. This means that when you press and release any of the numbered keys, its value is immediately added to the total shown in the register. Adding a set of numbers is therefore as simple as typing them all in. It has "duplex" functionality, meaning that it is possible to press keys from different columns at the same time to speed thing up.

The large lever on the right will clear the register, setting it to zero.

Subtraction is done by adding the tens-complement. The small digits on the keys are helpful for achieving this. To subtract a number, you must first mentally subtract 1, and then type it using the small digits. Precede the number by as many leading zeros (actually nines) as is needed to reach past the left of the current value in the register. The small metal tabs are used to block a carry, and using one here avoids the necessity of pressing any further leading zeroes in the number you are subtracting.

Multiplication is done by repeated addition. If you can press the keys for entering one of your factors all at the same time, it is easy to press that set of keys several times to get multiples of that number. Shift your fingers one column to the left to add multiples of ten times your number, and so on for higher columns.
For example to multiply 6798 by 24, press 6798 down four times in the last 4 columns, shift a column to the left and press the same pattern of keys twice.

Many tricks were devised for other kinds of calculations. To increase speed and touch-typing accuracy, operators often only used the bottom half of the keyboard. Instead of entering a high digit such as 8 directly, they would press 4 twice. This reduces the need for hand movement, and is easier to do without looking.


"Controlled-Key" mechanism

If you press down on a key but release it before it is pressed all the way in, the mechanism of the Comptometer would not be able to register the digit you wanted. To avoid this leading to calculation mistakes, a safety mechanism was used. When a partial key press occurs, all the keys in the other columns become locked. The partial key press will not have affected the number in the register, so you can then press the intended key completely to rectify the problem. You will have to press the red button at the back right to release the locked columns to continue.


Videos

Here is a video where I demonstrate the various features of my Model J Super Totalizer Comptometer.

In this video I demonstrate how to do the four basic arithmetic operations on the Comptometer.

This video shows the Model E Comptometer.


Comptometer Simulator

I have created a simulation of the Comptometer using javascript. If you click the link below, the simulation will open in a new window. If you are using a touch screen, then on most browsers you will be able to press multiple keys at the same time.

Start the Comptometer Simulator


Models

The first model (with a wooden case) and the subsequent models A to E are very rare, and won't be discussed here in detail. The most common shoebox models are F, H and J. The serial number limits are based on observed examples, so machines with numbers outside these ranges may exist.

ModelYearsS/N rangeNumberCharacteristics
Wood 1887-1903 10-6244 6300 Wooden case
Front of case is right-angled, with a flat glass window over the register.
Complicated clearing mechanism with a wheel and a small lever.
A 1904-1906 15000-20603 5700 First model with copper-plated steel case.
Front of case is right-angled, with a flat glass window over the register.
First model to have Duplex (multiple key press) functionality.
First model to have a clearing handle.
B 1906-1909 25000-33461 8500 First with S-curve shaped front of case.
Carry-blocking tabs are shaped and closer to keys.
C 1909-1912 35000-38602 3700 Keys made of composite
C-light 1911-1912 40000-48648 8700 Keys made of celluloid
Lighter key action
D 1913-1913 49000-49154 200
E 1913-1915 54000-61612 7700 First to have the Controlled Key system.
Only model to use guards on the side of the keys to detect inaccurate keystrokes.
White Controlled Key release button
F 1915-1920 100000-142337 42400 Front side panel of case has no decoration.
Clearing lever pivot is located just beyond the 9 keys.
Clearing lever angled towards the user.
Rear side panel of case lists series of patents.
Embossed decoration on the side panels is the same colour as rest of the case.
First with a red controlled key release button
Keys are black and white.
H 1920-1927 200000-248508 48600 Front side panel of case has Comptometer logo.
Clearing lever pivot is located between the 4 and 5 keys.
Clearing lever angled vertically.
Rear side panel of case has Comptometer logo. The name plate lists the patents.
Decoration on the side panels of the case are painted black to contrast with the case.
Keys are black and white.
Case is a centimetre longer at the front, with the S curve less steep, to make room for the new clearing mechanism.
J 1928-1938 J245489-J346384 100900 The serial number is preceded by the letter J.
Keys are green and white.
K 1934-1950 350000-?????? Electrically driven.
Metal casing, painted very dark brown.
Keys are all the same length.
Casing has a rear leg to tilt the keyboard.
Clearing lever ends shaped like a tab rather than a round handle.
M 1939-1950 400000-?????? Rounded metal casing, painted dark green.
Clearing lever inside the casing instead of on the side.
New Comptometer logo on the front.
Carry-blocking tabs have small white/green key tops.
First with shutters that hide leading zeroes automatically.
3D11 1950-1957? Controlled-key release button in front of keyboard, and green instead of red.
Automatic Controlled-key release button on the left of keyboard, useful in multiplication/division.
No Comptometer logo on the front.
Decimal pointers are below the register.
992/99C 1950-1961? Electrically driven version of the model 3D11.
No automatic Controlled-key release button on the left of keyboard.
No Comptometer logo on the front.
Decimal pointers are below the register.
616CE 1957-1961? Better known as the "Customatic".
Electrically driven, similar to the 992.
Electric clearing mechanism.
A slider to the left of the keyboard for setting the "Customatic Key Control".
Light grey casing.
Decimal pointers are below the register.

There is little or no external difference between the H and J models. They use exactly the same casing, and even their serial numbers overlap during the time when the stock of H model mechanisms were used up and the production of the J model mechanisms was built up. There were apparently several internal mechanical improvements, so the ones with the improved mechanisms had their serial number preceded by the letter J. They started using green keys on the model J instead of black ones, but as keys were often replaced this is not a completely reliable characteristic.

The electrically driven model K was like an electric typewriter in that the electricity was used to generate the force needed to activate the mechanism so that the key presses could be kept very light. It had a redesigned case that raised the rear end so that the keyboard sloped at the same angle as the previous models to compensate for the fact that all keys now had the same amount of travel.

The model M also has a variant built during the war, dubbed the model WM. Due to a metal shortage its parts were redesigned to use less metal (e.g. internal plates and levers were thinner and had holes punched in them). It looks the same as the normal model M but is much lighter in weight.


My Model E Comptometer

Comptometer Model E

This is a 12-column Model E Comptometer. This model was the first to include the "Controlled-Key" error detection, but also has guards on the side of the keys. If the metal guard is pressed down without first pressing the button itself, then the key will not travel further. This guards against the user accidentally catching an adjacent button during a button press. This system was dropped in subsequent models, probably because it was too complicated, the keys were prone to breaking, and because the problem it is guarding against is not common in trained operators.

My machine has serial number 56337, and was made in 1913 or 1914. This Comptometer is in fairly good condition, except that the left-most column of keys is locked. Presumably the guard system for that column is stuck. The zeroing mechanism often fails to fully reset when the handle is moved slowly. The Controlled-Key reset button is normally white in the Model E, but has been replaced here with a later red one. Some of the keys have broken during its working lifetime causing the key rod to come away from the flat stem of the guard. These keys have been patched up either by binding them together with a bit of metal wire, or by riveting them together with the key in the depressed state, effectively disabling the guard for that key. It is interesting to see that the base plate of the case for the 12-column model was built by joining together two smaller ones.


Comptometer Model E
Comptometer Model E, side
Comptometer Model E, top
Comptometer Model E, keys
Comptometer Model E, keys close-up
Comptometer Model E, register cover removed
Comptometer Model E, key
Comptometer Model E, key action
Comptometer Model E, key action
Comptometer Model E, key action
Comptometer Model E, key action
Comptometer Model E, key action
Comptometer Model E, key action
Comptometer Model E, removed key, front
Comptometer Model E, removed key, side
Comptometer Model E, removed key, back
Comptometer Model E, removed fixed key, front
Comptometer Model E, removed fixed key, back
Comptometer Model E, removed fixed key, side
Comptometer Model E, inside case


See the Video section on this page if you want to see the key guard system in action.


My Model J Comptometer

Comptometer Model J

This 10-column Model J Comptometer looks rather different from its original state. In the late 1940s or the 1950s it has been reconditioned, during which the casing has been wrinkle painted green, and the key-tops replaced with those from a model M or later. It has unfortunately been stored in poor conditions - the paint has discoloured and has begun to flake off.

Its internal mechanism is in fine condition, and needed only a little bit of lubrication to make it work perfectly.

This machine has serial number J314420. It has been said that the first two digits of the J number roughly match the year of production, but that is not quite accurate. The numbers range from about J245489 to J346384, which were produced from 1926 to 1938, so the machines were made about 2 to 4 years later than the first serial number digits indicate. My machine was therefore probably made in 1934.


Comptometer Model J
Comptometer Model J, Serial Number
Comptometer Model J, Plate
Comptometer Model J, Oil hole
Comptometer Model J, Case
Comptometer Model J, from above
Comptometer Model J, Register internals close up
Comptometer Model J, Mechanism left side
Comptometer Model J, Mechanism right side
Comptometer Model J, Clearing mechanism
Comptometer Model J, Clearing mechanism
Comptometer Model J, Mechanism bottom side



Super Totalizer

Comptometer ST

A special version of the Model J was made, called the Super Totalizer. The mechanism and case of the model J is extended at the front to add a second register. This register has a lever on the right that causes the number shown on the normal register to be added to it, and which also then clears the normal register. The lever on the left clears the extra register.

The extra register also has a row of buttons that when pressed and locked down move a cover over the corresponding digit to hide it. Any carry operation from a covered digit to a still visible one is suppressed.

This version has the normal J serial number, but also a second serial number especially for the Super Totalizer. I found the following numbers in other online collections:


J numberS numberKeyboardSource
J315804S73910 columnsPaul Breedveld
J316912S84310 columnsFred Haeghens
J316821S11318 columnsRechenmaschinen illustrated, H.van Noort
J317799S130812 columnsJay M. Goldman
J317808S131812 columnsComputarium, François Koeller
J317834S133512 columnsWorthpoint / eBay
J317903S141512 columnsMy own.
J321777S162510 columns, sterling (no farthings)John Wolff
J324639S185410 columnsComputer History Museum
J324720S192810 columnsRechner lexikon, Valéry Monnier
J324725S195710 columnsCris vande Velde
J327695S232112 columns, sterling (no farthings)John Wolff, not shown on his website
J339128S25948 columnsCris vande Velde
J339163S26208 columnsNational Museum of American History
J342586S270812 columnsOnline auction
J345247S315010 columnsMy own. In very poor condition.

It is not clear whether the S numbering started at 0 or 500, and it probably did not go further than 3300, so it is likely that between 2800 and 3300 Super Totalizers were produced.
Between S1308 and S1415, the S numbers rise a little faster than the J numbers. This might mean that some previously produced J Comptometers were being converted to STs. Note also that the second and third ones on the list have contradictary numbers.

For some reason the Super Totalizer was hardly ever shown in advertisements. Instead, the electric model K was promoted much more heavily. There was no Super Totalizer version of the model K, but later there were ST versions of the mechanical model M. It seems that the ST models were more popular in Europe and India than in the USA.

My Super Totalizers

Here are some pictures of my Super Totalizer (J317903/S1415). It is in very good working condition, but has had some repairs or restoration done. In particular, 9 of the key tops have been replaced with reproductions, and the celluloid windows have been replaced with more modern plastic.

Comptometer Super Totalizer
Plate
Keys
Register
Register
Clearing handle
Key release
Case logo
Case decoration
Serial number
Adding lever
Totalizer clearing handle


I have recently acquired a second ST in rather poor condition (J345247/S3150), but which can be used for spare parts. It has 10 columns of keys, but their plastic tops have degraded, and some of them are missing. The black and white ink of the key numbers had expanded and spread, so I have cleaned the keys before taking these pictures. The clearing handle is badly bent, some screws are missing, as is one of the extra register's blinds and its plastic window. The mechanism had seized up, especially the mechanism of the extra register, but I have managed to get it mostly working again just by spraying in some silicone lubrication. Unfortunately the clearing mechanism tends to get stuck and I have not yet found the cause of that.
The most interesting thing about this ST is its late model number, which allows a fairly accurate estimation for the number of model ST Comptometers produced.

Comptometer Super Totalizer
Plate
Keys
Clearing handle
Serial number



Books and Manuals

There are too many books to list here, so I have put them on a separate Comptometer Books and Manuals page.



Tables

Felt & Tarrant printed many small tables to help the operator with common calculations. Such tables were usually printed on thick cardboard for durability. In the 1920 edition of "Easy Instructions for operating the Controlled-Key Comptometer" a list is given of various tables that were available at that time. I reproduce that list here. The ones on this list that I own are marked by an asterisk.

Form NumberTitleDescription
1Tonnage TableGives the decimal part of a ton of any number of pounds.
3Lumber TableGives result of dividing 12 into any dimension up to 11 7/8.
4*Discount TableGives the net of chain discounts.
5Lumber TableGives number of board feet in pieces of various sizes.
6Gross TableGives the decimal for each fractional part of a gross and for each unit.
7*Grain TableGives the decimal part of a bushel of any number of pounds of different grains.
8Ten and 100 and 1000 X Inches and Fractions to Eighths TableUsed only in connection with the Engineering Model Comptometer for figuring beams, pipe, etc.
9Reciprocal TableUsed for making division quickly and easily by multiplication.
10British Currency TableGives the decimal part of a £ of any number of shillings and pence.
12British Currency TableGives the decimal part of a £ for pence and 32nd fractions.
21Quarters and Pounds of a Ton TableGives the decimal part of a ton of any number of Quarters and Pounds.
22Quarters and Pounds of a Cwt. TableGives the decimal equivalents of a Cwt. from 1/2 lb. to 3 qrs. 27 lbs.
24Interest TableGives the interest on $1.00 for different numbers of days at different rates.
25Net Discount TableShows the net left from $1.00 after discounting for the required number of days.
26Decimal TableUsed for figuring elapsed time. It gives the decimal part of a 360-day year up to any date.
29*Decimal Equivalents of Fractions TableGives decimal equivalents of fractions from 1/4 to 63/64.
32Cooperage TableUsed to determine how many staves of one size are equivalent to another size.
33*Interest TableGives the interest on $1.00 for one day for rates from 1/8 % to 12 7/8 %.
35*Payroll TableGives the decimal part of a month for any number of days and eighths of days.
36Insurance Cancellation TableShows decimal part of the year for months and days.
37Figuring Elapsed Time TableShows decimal part of a year for each day.
38Pounds, Ounces, and Drams TableGives the decimals of a 16-oz. pound for any number of drams and ounces.
184Interest TableGives the interest on $100. at 7% for from 1 to 364 days.
191Grain TableGives the Dockage and the net bushels per 1000 lbs. for different rates of dockage.
205Weights per Foot and Inch for Rounds, Squares, etc. of Different Thicknesses TableEnables one to get the weight of a piece.
234Iron and Steel TableGives the price per 100 lbs. at .01 to $100. per gross ton.
237Interest TableUsed for figuring interest on a 365-day basis, where interest rates run from 1 to 12%.

Decimal Equivalents of Common Fractions To be used in Connection with the Comptometer.
Felt & Tarrant Mfg. Co., Chicago, U.S.A.
Series No. 2
108mm × 164mm

This card was included when I bought the 1911 edition of "Methods of Operating the Comptometer", so is likely from around that time, especially since the picture on it is of a model B or C Comptometer. The card is signed on the back by Adelina Artesani who according to the 1900 and 1910 census was born in 1894 and resident in Boston, MA.

Common Fractions card, front
Common Fractions card, back
Common Fractions card, hi-res scan


Decimal Equivalents of Common Fractions To be used in Connection with the Comptometer.
Comptometer Division, Felt & Tarrant Mfg. Co., Chicago, Illinois
Form 29
102mm × 235mm

This card was included when I bought the "Table of Reciprocals" book, and it supplements that book by supplying some fractions that have numerators other than 1. Unlike most of the other cards, this one is printed partly in colour. It has no copyright year, but was probably printed in the 1940s as it has a picture of the model M.

Common Fractions card, front
Common Fractions card, hi-res scan front
Common Fractions card, hi-res scan back


Discount Table Showing net of $1.00 after discounts, shown at top and side, are taken off.
Comptometer Co., Chicago, U.S.A.
Form No. 4
165mm × 279mm

This card has no copyright year, but was probably printed in the 1940s as it has a picture of the model M. It is likely that earlier prints of this card exist.

Discount Table card, front
Discount Table card, hi-res scan front
Discount Table card, hi-res scan back


Grain Table Pounds Expressed in Decimal Parts of a Bushel.
Felt & Tarrant Mfg. Co., Chicago, U.S.A.
Form 7
117mm × 267mm

This card has no copyright year, but was probably printed in the early 1920s as it has a picture of the model H.

Grain Table card, front
Grain Table card, hi-res scan front
Grain Table card, hi-res scan back


Interest Table (360-day basis) To be used in Connection with the Comptometer
Felt & Tarrant Mfg. Co., Chicago, U.S.A.
Form No. 33
225mm × 159mm

This card has no copyright year, but was probably printed in the early 1920s as it has a picture of the model H.

Interest Table card, front
Interest Table card, hi-res scan front
Interest Table card, hi-res scan back


Pay Roll Table Decimal Equivalents of Days and Eighth Fractions of Days, for 24-31 Day Months also Minutes expressed in Decimal Equivalents of an Hour.
Comptometer Co., Chicago, U.S.A.
Form No. 35
195mm × 322mm

This card carries a copyright year of 1925, but it must have been a reprint from the 1940s as it has a picture of the model M.

Pay Roll Table card, front
Pay Roll Table card, hi-res scan front
Pay Roll Table card, hi-res scan back


Decimal Equivalents of Fractions from 3rds to 26ths inclusive To be used in Connection with the Comptometer.
Comptometer Co., Chicago, U.S.A.
Form No. 368
185mm × 235mm

This card has no copyright year, but was probably printed in the 1940s as it has a picture of the model M.

Fractions card, front
Fractions card, hi-res scan front
Fractions card, hi-res scan back


Decimals of a Foot for each 1/8 of an Inch To be used in Connection with the Comptometer in Figuring Lumber, Steel Beams, Angles, Etc.
Comptometer Co., Chicago
Form No. 386
152mm × 253mm

This card carries a copyright year of 1925, but it must have been a reprint from the 1940s as it has a picture of the model M.

Decimals of a Foot card, front
Decimals of a Foot card, hi-res scan front
Decimals of a Foot card, hi-res scan back


Ounces and Drams Reduced to Decimal of a Pound Table of Decimal Equivalents to be used in connection with the COMPTOMETER
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 3
253mm × 192mm

This piece of paper has no copyright year, but it has a picture of the Model H or J, and I suspect it is from about 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

Ounces and Drams Reduced to Decimal of a Pound
Ounces and Drams Reduced to Decimal of a Pound, scan


WAGES TABLE FOR 48-HOUR WEEK To be used in connection with the Comptometer
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 5
304mm × 178mm

This piece of paper has no copyright year, but it has a picture of the Model H or J, and I suspect it is from about 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

Wages Table For 48 Hour Week
Wages Table For 48 Hour Week, scan


For Calculating TIMBER SPECIFICATIONS Table to be used in connection with the COMPTOMETER
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 6
354mm × 240mm

This piece of paper has no copyright year, but it has a picture of the Model H or J, and I suspect it is from about 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.
It is stamped with the name of the company that used it, W.H. Wheeler & Sons, Portsmouth.

For Calculating Timber Specifications
For Calculating Timber Specifications, scan


For Calculating the Weight of Deals, Battens, and Boards at 66 cubic feet to the Ton Table of Decimal Equivalents to be used in connection with the COMPTOMETER
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 7
228mm × 240mm

This piece of paper has no copyright year, but it has a picture of the Model H or J, and I suspect it is from about 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

For Calculating the Weight of Deals, Battens, and Boards
For Calculating the Weight of Deals, Battens, and Boards, scan


GROSS, Each Fractional Part & each 144th To be used in connection with the COMPTOMETER. For Figuring Gross Invoices, Inventories, Plate Glass, etc.
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 8
209mm × 260mm (1925), 203mm × 256mm (1934)

This piece of paper has no copyright year, but it has a picture of the Model H or J, and I suspect it is from about 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

Gross, Each Fractional Part and each 144th
Gross, Each Fractional Part and each 144th, scan


This is a later print of the same table. It has a picture of the Model K so probably dates from about 1934.

table_gross1
table_gross2


Decimal Part of a Year for Each Day on a 365-Day Basis To be used in connection with the COMPTOMETER
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 9
184mm × 360mm

This piece of paper has a copyright year of 1914, though it was printed at a later date. From the dates used in the examples printed on the back I suspect it is from 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

Decimal Part of a Year for Each Day on a 365-Day Basis
Decimal Part of a Year for Each Day on a 365-Day Basis
Decimal Part of a Year for Each Day on a 365-Day Basis, scan
Decimal Part of a Year for Each Day on a 365-Day Basis, scan


Annas & Pies as Decimal of One Rupee Table of Decimal Equivalents to be used in connection with the COMPTOMETER
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 10
328mm × 211mm

This piece of paper has no copyright year, but it has a picture of the Model H or J, and I suspect it is from about 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

Annas and Pies as Decimal of One Rupee
Annas and Pies as Decimal of One Rupee, scan


QRS. & LBS. into CWT. and QRS. & LBS. into TON To be used in connection with the COMPTOMETER
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 21, Dec. Card No. 22
151mm × 239mm (1925), 164mm × 264mm (1934)

This piece of paper has no copyright year, but it has a picture of the Model H or J, and I suspect it is from about 1928. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

QRS. and LBS. into CWT
QRS. and LBS. into TON
QRS. and LBS. into CWT, scan
QRS. and LBS. into TON, scan


This is a later print of the above tables. It has a picture of the Model K so it is probably from about 1934.

QRS. and LBS. into CWT
QRS. and LBS. into TON
QRS. and LBS. into CWT, scan
QRS. and LBS. into TON, scan


Decimal Equivalents of Common Fractions To be used in Connection with the Comptometer.
FELT & TARRANT LTD., Aldwych House, Aldwych, London, W.C. 2.
Dec. Card No. 29
127mm × 203mm

This card has no copyright year, but I suspect it is from about 1928. It is printed by the UK company. It has a list of useful conversion factors on the back.

Decimal Equivalents of Common Fractions, front
Decimal Equivalents of Common Fractions, back
Decimal Equivalents of Common Fractions, scan, front
Decimal Equivalents of Common Fractions, scan, back


Pence & Sixteenths of One Shilling and Pence & Thirty-Seconds of One Shilling To be used in connection with the COMPTOMETER
Felt & Tarrant, Ltd., London.
267mm × 209mm

This piece of paper has no copyright year but probably dates from 1934. It is printed by the UK company, and lists the various Felt & Tarrant branch offices around the country.

table_pence1
table_pence2
table_pence3
table_pence4



Comptometer News magazine

Comptometer News.
Published now and then for Comptometer Operators throughout the World
Published by Felt & Tarrant Manufacturing Co., Chicago, U.S.A.
Frank T. Hess, Editor
1926-19??
32-36 page stapled magazine
153mm × 225mm (Vol I), 153mm × 230mm (Vol III-VIII)

This is a magazine aimed at the operators of the Comptometer, who were mostly young women. It contains mostly office gossip, birth and marriage announcements, and success stories. It gives a fascinating view on the society of the time.

The magazine appeared approximately 4 times a year, from December 1926 until at least 1938. I do not know when it ended its publication, but the copyright was renewed in 1948 so maybe it was still being published then or the company had plans to restart publication.

Comptometer News, Volume I, Number 1, December 1926, 32 pages (PDF, 11.6 MB)
Comptometer News, Volume I, Number 2, February 1927, 32 pages (PDF, 13.4 MB)
Comptometer News, Volume I, Number 3, June 1927, 32 pages (PDF, 15.0 MB)
Comptometer News, Volume I, Number 4, September 1927, 32 pages (PDF, 13.4 MB)
Comptometer News, Volume III, Number 1, January 1929, 36 pages (PDF, 17.0 MB)
Comptometer News, Volume III, Number 2, April 1929, 32 pages (PDF, 14.8 MB)
Comptometer News, Volume III, Number 3, July 1929, 32 pages (PDF, 14.0 MB)
Comptometer News, Volume III, Number 4, October 1929, 32 pages (PDF, 14.5 MB)
Comptometer News, Volume IV, Number 1, February 1930, 36 pages (PDF, 17.0 MB)
Comptometer News, Volume IV, Number 2, April 1930, 32 pages (PDF, 13.5 MB)
Comptometer News, Volume IV, Number 3, September 1930, 32 pages (PDF, 14.4 MB)
Comptometer News, Volume VIII, Number 1, February 1936, 36 pages (PDF, 16.2 MB)
Comptometer News, Volume VIII, Number 3, October 1936, 36 pages (PDF, 17.3 MB)
Comptometer News, Volume X, Number 1, Winter 1938, 36 pages (PDF, 18.0 MB)
Comptometer News, Volume 1, Number 1, December 1926
Comptometer News, Volume 1, Number 2, February 1927
Comptometer News, Volume 1, Number 3, June 1927
Comptometer News, Volume 1, Number 4, September 1927
Comptometer News, Volume 3, Number 1, January 1929
Comptometer News, Volume 3, Number 2, April 1929
Comptometer News, Volume 3, Number 3, July 1929
Comptometer News, Volume 3, Number 4, October 1929
Comptometer News, Volume 4, Number 1, February 1930
Comptometer News, Volume 4, Number 2, April 1930
Comptometer News, Volume 4, Number 3, September 1930
Comptometer News, Volume 8, Number 1, February 1936
Comptometer News, Volume 8, Number 3, October 1936
Comptometer News, Volume 10, Number 1, Winter 1938

Supplements were added to the Comptometer News magazine to cater to specific regions. Shown here is the Australian Supplement that was added to the issues from volume 3 & 4 of the magazine. There were UK supplements too.

Comptometer News Australian Supplement, Volume 1, Number 3, July 1929, 4 pages (PDF, 2.2 MB)
Comptometer News Australian Supplement, Volume 1, Number 4, August 1929, 6 pages (PDF, 3.0 MB)
Comptometer News Australian Supplement, Volume 1, Number 5, December 1929, 6 pages (PDF, 3.1 MB)
Comptometer News Australian Supplement, Volume 1, Number 6, July 1930, 6 pages (PDF, 3.0 MB)
Comptometer News Australian Supplement, Volume 2, Number 1, February 1931, 4 pages (PDF, 2.1 MB)
Comptometer News Australian Supplement, Volume 2, Number 2, April 1931, 4 pages (PDF, 1.9 MB)
Comptometer News Australian Supplement, Volume 1, Number 3, July 1929
Comptometer News Australian Supplement, Volume 1, Number 4, August 1929
Comptometer News Australian Supplement, Volume 1, Number 5, December 1929
Comptometer News Australian Supplement, Volume 1, Number 6, July 1930
Comptometer News Australian Supplement, Volume 2, Number 1, February 1931
Comptometer News Australian Supplement, Volume 2, Number 2, April 1931

The Comptometer News supplement for the UK was called "British Brevities". The second one here includes the reply card for the Christmas dinner invitation.

"British Brevities" of the Comptometer News, Number 8, March 1930, 8 pages (PDF, 3.8 MB)
"British Brevities" of the Comptometer News, Number 10, October 1930, 16 pages (PDF, 7.1 MB)
British Brevities of the Comptometer News, Number 8, March 1930
British Brevities of the Comptometer News, Number 10, October 1930
British Brevities of the Comptometer News, Christmas Dinner Invitation, front
British Brevities of the Comptometer News, Christmas Dinner Invitation, back

This is the envelope that was used for sending the Comptometer News in, in particular the February 1936 issue. Note that even this envelope is marked with its own publication number, FORM 523.

Comptometer News Envelope
Comptometer News Envelope
Comptometer News Envelope


Advertisements, Booklets, Leaflets, and Letters

There are too items to list here, so I have put them on a separate Comptometer Advertisements, Booklets, Leaflets, and Letters page.



Newspaper Articles

I don't own any physical copies of Comptometer newspaper articles. I have however found quite a few interesting articles in online newspaper and magazine archives. There are too many to list here, so I have put them on a separate Comptometer Articles page.



Paraphernalia

There are too many paraphernalia to list here, so I have put them on a separate Comptometer Paraphernalia page.



Patents

The Felt & Tarrant company, and Dorr Felt in particular, filed a lot of patents for all aspects of their inventions and designs. Below is a list of those that relate to the shoebox Comptometer. I have omitted from this list all patents for their other office machines, as well as patents for motorized or powered versions of the Comptometer. Some of the patents listed were never used in any production models, or used only for a short time on some models prior to the model F. The most important ones are displayed in bold type.

PatentFiling datePublish dateNameDescription
US 371,496 12 Mar 1887 11 Oct 1887 Dorr E. Felt First version of the Comptometer, which had a wooden case.
US 568,021 14 Jun 1895 22 Sep 1896 Dorr E. Felt Comptograph
US 661,121 2 May 1898 6 Nov 1900 Dorr E. Felt Comptograph improvements.
US 671,109 24 Oct 1900 2 Apr 1901 Dorr E. Felt Comptometer adapted for Sterling currency
US 733,379 3 Nov 1902 14 Jul 1903 Dorr E. Felt Case lining to reduce sound. Presumably used in Model A.
US 762,520 29 Jun 1903 14 Jun 1904 Dorr E. Felt Improved mechanism to reduce force needed. Presumably used in Model A.
US 762,521 29 Jun 1903 14 Jun 1904 Dorr E. Felt Improved register. Presumably used in Model A.
US 767,107 3 Aug 1903 9 Aug 1904 Dorr E. Felt New clearing mechanism. Presumably used in Model A.
US 960,528 16 Sep 1908 7 Jun 1910 Dorr E. Felt Improved mechanism. Adds carry-blocking buttons. Used in Model B.
US 982,416 4 Apr 1910 24 Jan 1911 Dorr E. Felt Mechanism to detect buttons pressed accidentally. Used later in Model E.
US 982,417 22 Aug 1910 24 Jan 1911 Dorr Eugene Felt Mechanism to detect buttons pressed accidentally. Used later in Model E.
US 992,950 18 Dec 1909 23 May 1911 Dorr E. Felt Mechanism to signal partial key stroke, via column indicator and bell.
US 996,009 4 Mar 1910 20 Jun 1911 Dorr E. Felt Improved carry to reduce key force needed. Presumably introduced in Model C-Light.
US 1,003,723 6 Jan 1911 19 Sep 1911 Dorr E. Felt Improved key-action (heavy to start, lighter through the down-stroke). Presumably used in the Model C-Light.
US 1,028,344 25 Nov 1911 4 Jun 1912 Dorr E. Felt Controlled-key mechanism, locking other keys after partial key stroke.
US 1,066,096 12 Jul 1912 1 Jul 1913 Dorr E. Felt Improved controlled-key mechanism, not releasing partially pressed key until fully pressed.
US 1,072,933 5 Apr 1913 9 Sep 1913 Dorr E. Felt Complete controlled-key mechanism.
US 1,072,934 5 Apr 1913 9 Sep 1913 Dorr E. Felt Improved clearing mechanism, reduced jamming with improper use.
US 1,074,689 30 Sep 1912 7 Oct 1913 George Steninger Bollensen Keyboard with a fractions column
US 1,074,704 5 Apr 1913 7 Oct 1913 Dorr E. Felt Keyboard with several columns for common fractions
US 1,074,705 5 Apr 1913 7 Oct 1913 Dorr E. Felt More reliable clearing mechanism
US 1,110,734 3 Mar 1914 15 Sep 1914 Kurt F. Ziehm New Controlled-Key mechanism. Presumably introduced in the Model F.
US 1,154,897 9 Oct 1911 28 Sep 1915 Joseph Abram Turck Improved mechanism to reduce key force needed.
US 1,357,747 1 May 1918 2 Nov 1920 Joseph A. V. Turck New clearing mechanism. Introduced in Model H.
US 1,357,748 1 Dec 1919 2 Nov 1920 Joseph A. V. Turck Improvement on the new clearing mechanism, with bell. Introduced in Model H.
US 1,391,220 24 Apr 1920 20 Sep 1921 Joseph A. V. Turck Early version of the Super Totalizer.
US 1,449,639 19 May 1921 27 May 1923 Joseph A. V. Turck Controlled-key mechanism that also locks clearing lever.
US 1,714,964 12 Mar 1921 28 May 1929 Joseph A. V. Turck Column indicator for controlled-key mechanism.
US 1,751,609 8 Oct 1923 25 Mar 1930 Joseph A. V. Turck Block clearing handle when controlled-key mechanism active.
US 1,817,640 30 Apr 1929 04 Aug 1931 Neal Eberhart Newman; Frederick Adolph Niemann Peg-Board system.
US 1,840,378 27 Oct 1926 12 Jan 1932 Carlos Wittenmyer Carry blocking levers that are automatically released by carry.
US 1,902,597 29 Sep 1927 21 Mar 1933 Joseph A. V. Turck More reliable clearing mechanism. Presumably introduced in Model J.
US 1,927,856 29 Sep 1927 26 Sep 1933 Joseph A. V. Turck Operator-controlled locking of key columns and digits.
US 2,104,051 16 May 1935 4 Jan 1938 Frederick A. Niemann Super Totalizer digit blinds.
US 2,130,364 5 Nov 1934 20 Sep 1938 Frederick A. Niemann Super Totalizer.
US 2,149,817 5 Nov 1934 7 Mar 1939 Frederick A. Niemann Super Totalizer.
USD 113,817 26 Aug 1938 14 Mar 1939 Frederick A. Niemann, Alfred L. Mell Model M case design.
US 2,273,491 28 Apr 1939 17 Feb 1942 Haldon A. Leedy Vibration proofing mounting of mechanism and case
US 2,346,601 24 Feb 1941 11 Apr 1944 Frederick A. Niemann Hide leading zeroes
US 2,753,117 22 Sep 1954 3 Jun 1956 Emil C. Walker Customatic mechanism

Links

Biography of a Machine. In depth information about all aspects of the shoebox Comptometers. It is the source of much of the information on this page.
John Wolff's Web Museum's Comptometer page is a great overview of the Comptometer history, with lots of detailed information on the mechanisms.
Flash Simulator of the Comptometer.


© Copyright 2015-2016 Jaap Scherphuis, .