Felt's descripton of how it came about...
"It was near Thanksgiving Day of 1884, and I decided to use the holiday in the construction of the wooden model. I went to the grocer's and selected a box which seemed to be about the right size for the casing.
"It was a macaroni box, so I have always called it the macaroni box model. For keys, I procured some meat skewers from the butcher around the corner and some staples from a hardware store for the key guides, and an assortment of elastic bands to be used for springs. When Thanksgiving Day came, I got (home) early and went to work with a few tools, principally a jackknife.
"I soon discovered that there were some parts which would require better tools than I had at hand for that purpose, and when night came, I found that the model I had expected to construct in a day was a long way to be complete or in working order. I finally had some of the parts made out of metal and finished the model soon after New Year's Day 1885."
Comptometers were available in 8, 10, 12 and even 16-column versions as well as for British money (sterling), fractions, etc on special order. Except for the wooden-cased, A and B models, serial numbers appear next to the "1" key of the leftmost column of keys.
This earliest model had round keystems with springs between the keytops and the keyplate. The first examples had keytops of the "typewriter" variety with a metal ring surrounding a celuloid inset containing the character. Near the end of production, composition keytops were used.
The first known use was by the U. S. Treasury Dept in September, 1887 altho it is not known if this was the first true "sale" or placed on loan to gain commerical visability.
The "A" was the first of the steel case models which was to become the standard for the remainder for all "shoebox" models. The design was covered by Patent 733,379 and was a material factor in a later lawsuit with Burroughs. It is distinquished by the novel glass slab dial cover and elongated hanging decimal point indications. "Carry inhibitors" appeared as short protruding tabs for use during complementary subtraction.
With this model, the springloaded keys are replaced with flat stamped metal keystems. The spring mechanism was redesigned being located at the bottom of the keystems inside the case.
A significant new feature dubbed duplex, allowed keys in different columns to be operated at the same time. This made multipiplying a practical operation for Comptometers since shipping and billing almost always involved some quantity times a unit weight or price.
Felt's genius is clearly at work here. Whereas the original model (see above) recorded the keypress on the downstroke, this model recorded on the UPstroke! Beyond this, there were no safeguards and keys had to be given a full downstroke to prevent errors in operation, a very real concern that would not be addressed for another ten years.
Commentary from Bob Otnes...
|"The A-model turned the Comptometer from a useful curiousity into a major player in the business world. The duplex feature greatly extended the speed and utility of the device, but it took both skill and training to operate the machine. The book "Applied Mechanical Arithmetic" is one of the most detailed "how-to" books that I have seen for any calculator. No question, the A-model was a major turning point for the company."|
Apparantly some machines had a clean front panel while others carried 4 screws as needed by the A-model to hold the glass cover clamps. It provided no oil holes in the dial cover but had two in the keyplate above the 9-row and one or two on the right side.
The action of the canceling handle was particularly noisy and would produce a factory-like racket in offices when several were in operation simultaneously. It would seem that this model was produced only thru May of 1909 when the next (C) model came on the market.
As with the B-models, a machine may or may not have carried those useless front panel screws. And for those fascinated by the history of oil holes, the C-light model sported some >>29<< of them in the dial cover and keyplate presumably in response to an almost complete lack in the prior model.
The serious reader should read ahead at this point thru descriptions of the E-model and F-model to understand what follows and return here to continue this description.
For all the world, the D-model looks exactly like the F-model. Well, not quite. Like Sherlock Holmes' "dog that didn't bark", the visual clue is the missing "Controlled Key", normally found next to the 9-key of the rightmost column. A second clue is that the D-model machine is a full 2 lbs. lighter than its F-model cousin, each of its 8 columns having a quarter of a pound fewer parts. Both in cost of parts and assembly labor, it was surely cheaper to produce.
Since no more than 153 of this model were ever made (and only this one** example has come to light), one could speculate on why it was produced at all. A reasonable theory is that (ignoring the ill-fated E-model) the "D" and the "F" machines were introduced simultaneously at different price levels, both somewhat higher than the C-model being replaced. For customers who felt the Controlled Key feature might not be worth the extra expense, the D-model was available, at least for a brief period. It was probably dropped from production due to lack of demand as the Controlled Key was highly favored by Operators.
**Prior to the discovery of this lone example, I speculated on the nature of this mystery machine at length(Engineers) , believing it to be simply a special application of the E-model. Happily, I have been proven wrong.
Exactly what made Felt abandon this machine is unknown. It may well be that it proved too expensive and/or too trickey to manufacture. And/or field maintainence could have become a problem as the odd keytops may have broken more easily under heavy and constant use.
For a detailed discussion of E-model serial numbers, patents, mechanical anomolies, etc, click here.
A major feature was the presense of the "Controlled Key" (introduced on the ill-fated E-model) which locked the keyboard when any key was not fully depressed. Since these machines were operated very rapidly by trained operators, the ability to detect a partial stroke AND allow for immediate correction without losing the running sum, they were warmly received. It may well have been the principal reason for the great popularity of this model over its lifespan.
Again, the arrangement of oil holes was altered with this model, now having a single set of "bare" holes across the dial cover, an added set of "eyelet" holes just under the 1-row and 12 of the eyelet type above the 9-row with no holes on any side panels.
One possability is that it was prototyped as an earlier, perhaps quite different (maybe very different) design of the H-model clearing mechanism. A machine exists that seems to give some credence to that explanation.
The forward placement of the clearing lever allowed the operator to zero the register with a single motion of the little finger without altering her hand position over the keyboard. Internally, less obvious improvements included audible, tactile and visual clear signals (bell, key pressure and slight offset of register zeros). All these refinements improved operator speed and accuracy but at some cost in complexity of the mechanism which required the front of the machine be extended by about 1/2". Support for this major step forward included one of the most detailed technical manuals for mechanical devices ever produced.
By 1920, Felt & Tarrant had grown into a major presence in the office machine business and Dorr Felt would "kick off" the introduction of his new model with a gathering of his sales force in June at the Chicago factory. The H-model was a big hit with users and justifiably so what with its many operational and aesthetic improvements. It was produced until early 1926.
Altho the "J" had no major new features, many operational aspects were markedly improved and it received wide acceptance in the late "roaring 20s". The model was in constant production until the start of WWII concurrently with the newer electric (K) and "streamlined" (M) models. Many of the survivor examples were still in operation at major U.S. corporations until the late 1970s, a remarkable record spanning some fifty years of useful service.
Interestingly, the "J" was the only shoebox model to carry its alpha designation next to the serial numbers. And, according to Tom Thornton, F&T employee (1942-52), "the left two digits of the serial number was the year of manufacture" (except for production in postwar England).
In Sept of 1921, Turck received patent #1,391,220 (assigned to F&T, of course) for the basic design. Another patent issued in Sept of 1930 (# unknown) to Turck probably covers the "leading blank suppression" shutters that became standard on the later M-models.
The other patent appearing on the machine (#1,886,883) was issued to W.S.Johnson of Providence, RI in Nov of 1932 (filed over 11 years earlier). One wonders what connection there must have been since this design is similar to the Mechanical Accountant which Turck is said to have invented while living in Providence some 30 years prior.
This model is sometimes referred to as "duplex" because of the sub-total and grand-total registers. Such reference should not be confused with the duplex feature introduced with the A-model which allowed simultaneous depression of keys and was a significant operational feature (see above).
The machine pictured exhibits a strange "oozing" of the digits imprinted onto the light colored keytops. It seems that this problem affected only some machines produced in the 1930s and perhaps was due to a chemical interaction between the mastic used for the numerals and the keytop material.
Apparantly very few SuperTotalizers were ever made as only four or five have come to light.
Ray Mackay describes the process as it took place in Australia...
"During a difficult financial period (in the British Commonwealth), Comptometer distributors refurbished the older square (shoebox) models. Those had the copper plated case sprayed with a brown translucent lacquer.
"Before any respraying, the case was removed from the silver base plate (I'm not sure if the four case sides were separated) and the decimal indicators from the register cover. Also, all cork was removed from everywhere as cork does not like the ovens used for the enamelling.
"Factory reburbishing was a professional job. The new colour for the keyplate was smooth green baked enamel and baked wringle finish on the four side plates.
"The keyplate was removed as well as the little decimal pointers of the register cover. The decimal indicators and patent plate would be replaced. All cork lining was removed and later, replaced being refitted with new rivets.
"Where the keyplate was worn, it was replaced with a new one. Where it was in good condition, it was replated and the old serial numbers transferred to the new keyplate.
"On such factory/distributor rebuilds, the keytops were removed (whilst the machine was disassembled) by placing the keystem in a vice, removing the keytop with a specially designed forked lever and hammering on a new 3D11 extruded keytop with a leather mallet (the jaws of the vise were lined with copper to stop indentation on the keystem by the vise).
"The machine was stripped down to the frame and checked for chipped teeth on gears, worn bearings, pitted or grooved shafts, etc. The individual parts were washed in 'Shellite' and re-oiled as the machine was assembled.
"Prior to key fitting, all trigger mechanism adjustments were made so that the machines clicked over like a Swiss clock. The keyboard was then fitted and the keys reinstalled. Next, the machine was tested for a week by skilled operators before being returned to the customer or placed in rental service. Any machine found unsatisfactory was reprocessed at the trigger adjustment phase. This was because trigger adjustment relied on the accurate position of an eccentric bush that positioned the segment lever before any adjustment was made. The bush was adjusted to position the bellcrank accumulators stop correctly in relation to the accumulator's lantern pins. As you are looking from under the accumulators it was not always easy to get the adjustment right on.
"Cases finished in Black or by lesser standards may have been processed by second hand office equipment dealers or even performed by other companies on 'trade ins'. The official 'rebuild' was a thoroughly professional job and final testing before the keyplates were fitted was performed by the service manager.
"The import restriction into the U.K. had an impact and the Comptometer place in Deansgate in Manchester did rebuild machines. There, the standard Felt & Tarrant policy would apply.
"If you can find a Les Langley in the UK that worked on Comptometers he would know the Deansgate details. We also had a Don Rosier in Adelaide who was factory trained at Deansgate and is now a Doctor in South Australia. I contacted him a few times, as a friend, however I am afraid his interest in his past is not to high on his priorities."
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