Felt's descripton of how it came about...
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"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. Serial numbers did not appear on the first 100 or so machines. Except for the wooden-cased, A and B models, serial numbers appear next to the "1" key of the leftmost column of keys.
The keystems were round with springs between the keytops and the keyplate. The keytops themselves were of the "typewriter" variety with a metal ring surrounding a celuloid inset containing the character.
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, this model sported some >>29<< of them in the dial cover and keyplate presumably in response to an almost complete lack in the prior model.
No detail information is available regarding any of its features and we can only speculate on both its purpose and the reason for its brief lifespan. One possiblity is that it was produced on "special order" for a single customer with a unique need. Or it may simply have had a design flaw caught early in prodution. Until and unless one is unearthed, we may never know.
According to McCarthy, a project to convert Es to the next model (Fs?) was started around 1913-14 and assigned serial numbers commencing with 59000 (however, a machine carrying SN 60077 seems in all respects to be unconverted). This project may have been an effort to recover some of the investment in this slow selling model.
Note the clip from the Jan 24, 1911 patent (982,416) showing keystems with attached metal side plates and spring encased >>within<< the stem! The keytops were oblong, clearly to allow room for those side plates designed to detect "fat fingering" errors (this was brot to my attention by Kevin and Justin Odhner, caretakers of one of these rare machines).
A reading of this quite brief patent reveals Felt's devotion to providing operators with maximum error detection and correction capabilities. He states, in part, "The releasing devices are so located that they are depressed necessarily when the finger presses properly on the center of the key, but not when pressed on its margin."
Exactly what made Felt abandon this machine is (as yet) unknown. It may well be that it proved too expensive and too trickey to manufacture. Also, field maintainence could have become a problem as the odd keytops may have broken more easily under heavy and constant use.
This model carried a white "Controlled Key" rather than the more common red key that was to grace all future models.
A major feature was the presense of the "Controlled Key" (introduced on the elusive 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 was most welcome by customers. 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, it 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.
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".
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.
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.
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).
Apparantly very few SuperTotalizers were ever made.