Early Efforts in the
Recording Machine Art
The Art of recording the addition of columns of figures is old in principle, but not in practice. Many attempts to make a machine that would record legibly under all conditions failed. These attempts have been pointed out from time to time as the first invention of the recording-adding machine, especially by those desirous of claiming the laurels.
The first attempt at arithmetical recording for which a patent was issued, was made by E. D. Barbour in 1872 (see illustration on opposite page).
E. D. Barbour has also the honor of being the first inventor to apply Napier’s principle to mechanism intended to automatically register the result of multiplying a number having several ordinal places by a single digit without mentally adding together the overlapping figures resulting from direct multiplication. He patented this machine in 1872 just prior to the issue of his arithmetical recorder patent. (See page 181.)
The Barbour Machine
The printing device disclosed in connection with the Barbour machine for recording calculations was of the most simple nature, allowing only for the printing of totals and sub-totals.
Its manipulation consisted of placing a piece of paper under a hinged platen and depressing the platen by hand in the same manner that a time stamp is used. The ink had to be daubed on the type by a hand operation to make legible the impressions of the type.
The patent drawings of the Barbour machine are so fragmentary that it is almost impossible to draw any conclusion as to its functions without reading the specifications.
Fig. 1 represents the base of the machine, while Fig. 4 shows a carriage which, when in place, is superimposed above the base as illustrated in Figs. 3 and 5.
The operation of the machine is performed by first pulling out the slides B (shown in Fig. 1), which set the digital degrees of actuation of each order; and, second, by operating the hand-lever K, from its normal position at 0 to 1, if it is desired to add, or to any of the other numbers in accordance to the value of the multiplier if multiplication is desired.
The movement of the handle K, from one figure to the other, gives a reciprocation to the carriage, so that for each figure a reciprocation will take place.
Each of the slides B, has a series of nine gear racks; each rack has a number of teeth ranging progressively from 1 tooth for the first gear rack to 9 teeth for the last rack, thus the pulling out of the slides B will present one of the gear racks in line to act upon the accumulator mechanism of the carriage as the carriage is moved back and forth over it.
The accumulator mechanism consists of the register wheels M¹ and M² and the type wheels M³ and M⁴ mounted on a common arbor and a carry transfer device between the wheels of each order.
Operating between the accumulator wheels and the racks of plate B are a pair of gears, one in the form of a lantern wheel loosely mounted on the accumulator wheel shaft but connected thereto by a ratchet wheel and pawl connection; the other, a small pinion meshing with the lantern wheel on a separate axis, protrudes below the carriage into the path of the racks.
Thus as the carriage is moved by the reciprocating device connected with the hand-lever K, the pinions of the accumulator will engage whatever racks have been set and the numeral wheels and type wheels will be operated to give the result.
The numeral and type wheels have two sets of figures, one of which is used for addition and multiplication, while the other set runs in the opposite direction for negative computation or subtraction and division.
A plate arranged with sight apertures covers the numeral or register wheels, while the type wheels are left uncovered to allow a hinged platen F, mounted on the top of the carriage (see Fig. 3), to be swung over on top of them and depressed.
Attached to the platen F, are a series of spring clips d, under which strips of paper may be slipped (as shown by D, in Fig. 4), and which serves to hold the paper while an impression is taken.
Thus the Barbour invention stands in the Art as something to show that as early as 1872 an effort was made to provide means to preserve a record of calculations by printing the totals of such calculations.
The Baldwin Machine
The next effort in this class of machines is illustrated in a patent issued to Frank S. Baldwin in 1875 (see illustration on opposite page). The Baldwin machine is also of moment as having the scheme found in the machines known as the Brunsviga, made under the Odhner patents—a foreign invention, later than that of Baldwin, used extensively abroad and to a limited extent in this country.
The contribution of Baldwin to the Art of recording-calculating devices seems to be only the roll-paper in ribbon form and the application of the ink ribbon. The method used by Barbour for type impression was adapted and used by Baldwin; that is, the hinged platen and its operation by hand.
Of the illustrations shown of the Baldwin machine, one is reproduced from the drawings of the patent while the other is a photo reproduction of the actual machine which was placed on the market, but, as may be noted, minus the printing or recording device shown in the patent drawings.
Referring to the photo reproduction, the upper row of figures showing through the sight apertures in the casing are those of the numeral wheels which accumulate the totals, and which in the patent drawings would represent the type of the accumulator wheels for printing the totals of addition and multiplication or the remainders of subtraction and division.
From Drawings of Baldwin Patent No. 159,244
Baldwin Machine
The figures showing below serve to register multiples of addition and subtraction which would read as the multiplier in multiplications or the quotient in division. These wheels are the type wheels N, in the patent drawings, which serve the purpose of recording the named functions of calculation.
The means by which the type wheels of the upper row are turned through the varying degrees of rotation they receive to register the results of calculation, consists of a crank-driven, revolvable drum, marked E, which is provided with several denominational series of projectable gear teeth h, which may be made to protrude through the drum by operation of the digital setting-knobs g, situated on the outside of the drum.
These knobs, as shown in the patent drawings, are fast to radial arms, each of which serves as one of three spokes of a half-wheel device, operating inside the drum and pivoted on the inner hub of the drum.
These half wheels marked F, in the drawings, by means of their cam faces h¹, serve to force the gear teeth out through the face of the drum, or let them recede under the action of their springs as the knobs g, are operated forward and back in the slots x, of the drum provided for the purpose.
As will be noted from the photographic reproduction of the machine, these slots are notched to allow the arms extending through them to be locked in nine different radial positions, and that each of these positions are marked progressively from 0 to 9.
This arrangement allows the operator to set up numbers in the different orders by springing the setting-knobs g to the left and pulling them forward to the number desired, where it will become locked in the notch when released. This action will have forced out as many gear teeth in each order as have been set up by the knobs g in their respective orders.
The lateral positions of the projectable gear teeth correspond to the spacing of the type-wheels, and an intermediate gear G, meshing with each type, or register wheel, is loosely mounted on the shaft H, interposed between the said wheels and the actuating drum E, so that when the drum is revolved by the crank provided for that purpose, the gear teeth protruding from the drum will engage the intermediate gears G, and turn them and their type or register wheels as many of their ten points of rotation as have been set up in their respective orders of the setting devices of the drum.
Revolving the drum in one direction adds, while revolving it in the opposite direction subtracts, and repeated revolutions in either direction give respectively the multiple forms of addition or subtraction which result in either multiplication or division, as the case may be.
The actuating drum E, is provided with means by which it may be shifted to the left to furnish means for multiplying by more than one factor and to simplify the process of division.
The means for the carry of the tens consist of a series of teeth i, formed by the bent end of a pivoted spring-pressed lever arm which is pivoted to the inside of the actuating drum with the tooth protruding through a slot in the drum, so arranged as to allow motion of the tooth in a direction parallel to the drum axis.
From Drawings of Pottin Patent No. 312,014
Normally these teeth are held in a position to escape engagement with the intermediate gears G, but provision is made for camming the teeth i, to the left into the path of an intermediate gear of one order as the type or register wheel of the lower order passes from 9 to 0.
The parts which perform this function are the cam m, located on the left side of each wheel, the plunger M, which operates in the fixed shaft H, and which has a T-shaped head that, when projected into the path of the carrying teeth i, serve to cam them sidewise and bring about the engagement referred to, which results in the higher type or numeral wheel being stepped forward one space.
The cam-lugs j on the drum serve to engage and push back the T heads of the cam plungers M, after they have brought about the one-step movement of the higher wheel.
The printing device consists of a hand-manipulated frame pivoted to the main frame of the machine by the shaft t. The paper is supplied from a roll about the shaft t, and an ink-ribbon is fed back and forth from the rolls u and u¹ over bars of the printing-frame which protrude through slots in the casing and act as platens for the impression of the paper and ink-ribbon against the type.
It is presumed that the paper was torn off after a record was printed in the same manner as in the more modern machines.
The Pottin Machine
Eight years after the Baldwin patent was issued, a Frenchman named Henry Pottin, residing in Paris, France, invented a machine for recording cash transactions, which he patented in England in 1883 and in the United States in 1885 (see illustration on opposite page).
The form and design of the machine, as will be noted, correspond quite favorably with the scheme of the present-day cash register, although it lacks the later refinement that has made the cash register acceptable from a visible point of view.
The Pottin invention is named here as the first in which two of the prime principles of the recording-adders of today are disclosed; one is the depressable key-set feature and the other is the recording of the numerical items. The Pottin machine was the first known depressable key-set crank-operated machine made to add columns of figures and the first machine in which an attempt was made to print the numerical items as they were added.
Turning to the illustration of the U. S. patent drawings of the Pottin machine, the reader will note that there are four large wheels shown, marked B. These wheels are what may be called the type-wheels, although they also serve as indicator wheels for registering cash sales. The type figures are formed by a series of needles fixed in the face of the wheels.
The means employed for presenting the proper type figure for printing and likewise the indicator figures to indicate the amount set up in each denominational order was as follows:
Referring to Fig. 1, it will be noted that to each type-wheel is geared a spring-actuated segmental rack marked D, which, as shown in the drawing, is in contact with a pin marked i, which protrudes from the side of the depressed number (9) key.
The normal position of the rack D, is indicated in dotted lines showing the next higher sector which has not been displaced by key depression.
Each key, as will be noted from Fig. 7, is provided with one of the pins i, which is normally out of the path of the lug j, as the racks D, drop forward; but when any key is depressed the pin is presented in the path of the lug j, and stops further forward action of the rack.
It will be noted that the arrangement of the keys is such as will allow progressively varying degrees of action to the segmental racks D. This variation, combined with the geared relation of the type-wheels and racks is equivalent to a tenth of a rotation of the type-wheel for each successive key in the order of their arrangement from 1 to 9.
The means provided for holding the segmental racks D, at normal, also serves to hold a key of the same order depressed, and consists of a pivoted spring-pressed latch-frame marked E (see Figs. 7 and 8).
With such a combination, the depression of keys in the several orders will unlatch the segmental racks, and the racks, through the tension of their actuating springs, will turn the wheels and present a type corresponding to the numerical value of each key depressed.
A hand lever, marked R, located on left side of the machine provides power for printing the items. Another hand lever, marked J, serves to restore the segmental racks, type-wheels and the keys to normal, and through the co-operation of the lever R, adds the items to the totalizer numeral wheels, which are shown in Fig. 1 as the numbered wheels marked v.
The paper is supplied from a roll mounted on a hinged platen frame P¹, supported in its normal position by a spring P³. The paper passes under the roller P, which acts as a platen for the impression of the type. A shaft Q, passing under the frame P¹, is fast and rigidly connected on the left-hand side of the machine with the hand lever R, and acts as a pivot for the said lever and by means of lateral projections q, serves when the lever R is operated to engage the frame P¹, and depresses it until the needle types have pricked the numerical items through the paper.
A slit in the casing provided means for printing the item on a separate piece of paper or bill.
Although there is no means shown by which the paper is fed after an item is printed, it is claimed in the specification that the well-known means for such feeding may be employed. The actuating lever J referred to, is connected by a ratchet and geared action with the shaft F[3], so that a revolution is given the said shaft each time the lever is operated.
To the shaft F, (see Fig. 1) is attached a series of arms H, one for each order, which, as the shaft revolves in the direction of the arrow, engages a lug marked I, on the segmental racks D, thus rocking the segments back to normal, turning the type-wheels with them.
The return of the segment racks D, cause the back of the latch-tooth f¹, (see Fig. 8) to engage the latch-tooth f, of the latch bar E, camming it out of engagement with the keys so that any key that has been set will return by means of its own spring.
From Drawings of Burroughs Patent No. 388,118
Wm. S. Burroughs
The total or accumulator numeral wheels are connectable with the type or indicating wheels B, by an engaging and disengaging gear motion set up by the combined action of the hand levers R and J, which first cause such gear engagement, and then, through the return of the type wheels to zero, turn the accumulator wheels, thus transferring the amount of the item set upon the type wheels to the accumulator wheels.
The specification claims the machine is intended for use by cashiers, bank-tellers, and others, to record receipts or disbursements.
It is also claimed in the specification that instead of the needle type ordinary type may be used in combination with an inking ribbon if so desired.
One of the next attempts to produce a recording-adder was made by Wm. S. Burroughs, whose name sixteen years later was used to rename the American Arithmometer Co., now known as the Burroughs Adding Machine Co.
The first patent issued to Burroughs, No. 388116, under date of August 21, 1888, like the machine of Barbour and Baldwin, was designed to record only the final result of calculation.
On the same date, but of later application, another patent, No. 388118, was issued to Burroughs which claimed to combine the recording of the numerical items and the recording of the totals in one machine. Some of the drawings of this patent have been reproduced. (See opposite page.)
Machine of Early Burroughs Patent
Referring to the drawings of the Burroughs patent, it will be noted, that in outward form, the machine is similar to the Burroughs machine of today. To give a detailed description of the construction of the machine of this Burroughs patent would make tedious reading and take unnecessary space.
The principle involved in the mechanism for recording the items is very similar to that of the Pottin invention; the setting of the type wheels being effected as in the Pottin machine by means of segment gears which the depression of the keys serves to unlatch, and acts to gauge the additive degree of their movement.
Burroughs used the inking form of type proposed as an alternative by Pottin in his patent specification instead of the needles shown in the Pottin drawings.
In the Burroughs patent, as in the Pottin, it will be noted that there are two sets of wheels bearing figures, one set of which, marked J, situated at the rear, are the type-wheels, and the other set, marked A, at the front of the machine, are for the accumulation of the totals.
For each denominational order of the type and total wheels, there is provided an actuating segmental gear, consisting of a two-armed segmental lever pivoted to the shaft C, and having the gear teeth of its rear arm constantly in mesh with the pinion gear of the type-wheel J, and the gear teeth of the forward arm normally presented to, but out of mesh with the pinion gear of its total wheel A.
Each of these denominational actuators or segment gears is provided with a stop projection X², at the top end of its forward gear rack, which serves as a means for interrupting the downward movement of that end of the segment lever, and thus controls its movement as a denominational actuator.
It will be noted that instead of the key-stems acting directly as a stop for the denominational actuators, as in the Pottin invention, Burroughs used a bell crank type of key lever and the stop-wire C¹ as an intermediate means, and in this manner produced a flat keyboard more practical for key manipulation.
The stop-wires C¹, as will be noted, are arranged to slide in slots of the framework, and while normally not presented in the path of the stop-projection X², of the denominational actuators, it may be observed that by the depression of the proper key any one of them may be drawn rearward and into the path of the stop projection X², of its related actuator, and thus serve as a means to intercept the downward action of the actuator.
The denominational actuators in the Burroughs machine were not provided with spring tension that would cause them to act as soon as unlatched by depression of the keys as has been described in relation to the Pottin invention.
While the keys in the Burroughs machine, as in the Pottin invention, served also to unlatch the denominational actuators in their respective orders, no movement of the said actuators or type-wheels took place until a secondary action was performed.
The secondary action, or the operation of the hand lever, marked C⁵, attached to the shaft C, on its initial or forward stroke dragged the denominational actuators down by means of friction and thus set the type-wheels, and by means claimed in the specification, brought about the type impression to print the result of the key-setting or the item so set.
The backward or rear stroke of the hand lever caused the accumulator or total numeral wheels to be engaged and the item to be added to them.
From this single lever action it will be noted that there is an improvement shown over and above the Pottin invention in the fact that but one lever motion is required; Pottin having provided two levers so that in the event of error the operation of one lever would reset the machine without performing any addition or printing.
In the Burroughs invention, the motion of denominational actuators and their type-wheels not being effected through depression of keys, as in the Pottin machine, allowed any error in the setting up of an item to be corrected by the resetting of the keys and relatching of the gears, which it is claimed was provided for by operation of the lever marked B⁷ (Fig. 1 of the drawings).
As a means of supplying power to his denominational actuators, Burroughs provided what may be called a universal actuator common to all orders, composed of a rock-frame (arms D², loose on each end of actuating shaft C, and having their outward ends rigidly connected by the bar a⁹) and the arms E, fixed to each end of the shaft C.
Projecting from the inside of each of the arms E, are two lugs, b¹ and b³, which contact with the arms D² of the rock-frame as the shaft C is rocked back and forth by its hand crank C⁵, and thus lower and raise the rock-frame.
The means employed to transmit the reciprocating action of the universal actuator to such denominational actuators as may be unlatched by key depression, consists of a series of spring-pressed arc-shaped levers D¹, pivoted to the rock-frame bar a⁹, which bear against a pin b² fixed in the front arm of the denominational actuators.
Each of the levers D¹, is provided with a notch y, which serves on the downward action of the rock-frame to engage the pins b², of the denominational actuators and draw down with them such actuators as have been unlatched by key depression and to pass over the pins of such actuators as have not been unlatched.
When in the course of such downward movement the denominational actuators are intercepted by the stop-wires C¹, the yielding spring pressure of the levers D¹, allow the notches y, to slip over the pins b², and leave the denominational actuators and their type-wheels set for recording the item thus set up.
The means provided for impression of the type is shown in other drawings of a patent not reproduced here. The means provided consisted of a universal platen, which, the specification states, serves to press the ink-ribbon and paper against the type after all the figures of each item were set.
While Barbour, Baldwin and Pottin all used the universal platen to print the collective setting of type represented in the items or totals, as the case may be, each varied somewhat in detail. Baldwin used a toggle to press the platen toward the type, while Burroughs used a spring to press the platen against the type and a toggle to press it away from the type.
Burroughs claimed to have combined in his invention the printing of the totals, with the printing of the items, each of which it has been shown was claimed by the patentees of previous inventions but had not been combined in one machine prior to the Burroughs attempt.
The process for recording these totals in the Burroughs patent consisted of utilizing the action of the total wheels during their resetting or zeroizing movement to gauge the setting of the type-wheels.
The specification shows that, during the downward motion or setting of the denominational actuators, as they set the type wheels, the numeral wheels are out of gear and receive no motion therefrom; and that after the recording of each item and during the return motion of denominational actuators, the numeral or total wheels are revolved forward in their accumulative action of adding the items and thus registering the total.
Provision is made, however, when it is desired to print the totals, to cause the totalizing wheels to enmesh with the denominational actuators on their downward or setting movement, and for the unlatching of all the racks so that by operating the hand lever C⁵, the downward action of the racks will reverse the action of the totalizing wheels, which will revolve backward until the zeros show at the visible reading point, where they will be arrested by stops provided for that purpose. By this method the forward rotation accumulated on each wheel will, through the reverse action of zeroizing, give a like degree of action to the type-wheels through the denominational actuators. Thus the registration of the total wheels, it is claimed, will be transferred to the type-wheels and the record printed thereof as a footing to the column of numerical items that have been added.
To pass judgment on the recording machines of the patents that have been described, from the invention of Barbour to that of Burroughs, demands consideration, first, as to whether in any of the machines of these patents the primary features of legible recording were present.
The question as to operativeness respecting other features is of no consideration until it is proven that the means disclosed for recording was practical. As non-recording adding or calculating machines they were not of a type that could compete with the more speedy key-driven machines dealt with in the preceding chapters; therefore without the capacity for legible recording, these patents must stand as representing a nonentity or as statutory evidence of the ineffective efforts of those who conceived the scheme of their make-up and attempted to produce a recording-adding machine.
Without the capacity for legible recording, of what avail is it that the machine of one of these patents should disclose advantages over another? It may be conceded that there are features set forth in the Pottin and Burroughs patents that if operatively combined with legible recording would disclose quite an advanced state of the Art at the time they were patented. But credit for such an operative combination cannot be given until it exists.
There is no desire to question the ingenuity displayed by any of these inventors, but in seeking the first practical recording-adding or calculating machine we must first find an operative machine of that type; one which will record in a practical and legible manner regardless of its other qualifications.
The fact that the fundamental principle used for the impression of the type in the practical recorder of today is not displayed in any of these inventions, raises the question as to the effective operativeness of the printing scheme disclosed in the patents of these early machines.
In each of the four alleged recording-adding machine patents described, it will be noted that the means employed for printing was that of pressing the paper against the group of type by means of a universal platen or plate.
While with such a combination it may be possible to provide a set pressure great enough to legibly print a numerical item or total having eight to ten figures through an ink ribbon, it would not be practical to use the same pressure to print a single-digit figure, as it would cause the type to break through the paper. And yet in the numerical items and totals that have to be recorded in machines of the class under consideration, such wide variation is constantly encountered.
We are all familiar with the typewriter and the legible printing it produces. But suppose instead of printing each letter separately the whole word should be printed at once by a single-key depression, then, of course, single-letter words, such as the article “a” or the pronoun “I” would also have to be printed by a single-key depression. In this supposition we find a parallel of the requirements of a recording-adding machine.
Drawings of Ludlum Patent No. 384,373
If it were possible to so increase the leverage of the typewriter keys enough to cause a word of ten letters to be printed as legibly as a single letter is now printed, ten times the power would have to be delivered at the type-head. Then think what would happen with that same amount of power applied to print the letter “a,” or letter “I.” You would not question that under such conditions the type would break a hole in the paper. And yet the patentees of the said described inventions wanted the public to believe that their inventions were operative. But to be operative as recording-adding machines, they must meet such variable conditions as described.
It is useless to believe that a variation of from one to ten or more type could be printed by a set amount of pressure through an ink-ribbon and be legible under all circumstances.
While the needle-type of Pottin may have printed the items legibly enough for a cash register, it would not serve the purpose of a record for universal use. The use of regular type and the inking ribbon proposed in his specification would bring it within the inoperative features named.
The Ludlum Machine
In 1888, about two months prior to the issue of the Burroughs recording machine patent just referred to, a patent was issued to A. C. Ludlum for an adding and writing-machine. (See illustration on opposite page.)
It will be noted by reference to the drawings that the scheme is that of a typewriter with an adding mechanism attached.
The details of the typewriter may be omitted, as most of us are familiar with typewriters. A feature that differed from the regular typewriter, however, was that the machine printed figures only and the carriage operated in the opposite direction, thus printing from right to left instead of left to right.
A series of numeral wheels and their devices for the transfer of the tens, designed to register the totals, are shown mounted in a shiftable frame connected with the bar marked F, with the typewriter carriage, and is claimed to move therewith.
Each numeral wheel is provided with a gear marked G, which, as the carriage moves after writing or printing each figure of the item, is supposed to slide into mesh one at a time with an adding gear marked H, the engagement taking place from right to left. Or beginning with the right or units numeral wheel a higher order numeral wheel gear is supposed to shift through movement of the carriage into engagement with the adding gear H, each time a key is depressed.
The adding gear H, is supposed to receive varying degrees of rotation from the keys according to their numerical marking and to rotate the numeral wheel with which it happens to be engaged, a corresponding number of its ten marked points of registration.
Between the adding gear H, and the keys which act to drive it, is a ratchet and gear device consisting of the ratchet pawl pivoted to the adding gear H, the ratchet I⁶, and its pinion gear, the segment gear I² fast to the rock shaft I, the nine arms I¹ fast to the rock shaft and the pins I², which are arranged in the key levers to contact with and depress the arms I¹ of the rock shaft varying distances, according to the value of the key depressed. That is, supposing that the full throw of the key-lever was required to actuate the rock shaft with its gear and ratchet connection to give nine-tenths of a revolution to the numeral wheel in adding the digit nine, the pin I² in the (9) key-lever would in that case be in contact with its arm I¹, of the rock shaft, but the pins I², of each of the other key levers would be arranged to allow lost motion before the pin should engage its arm I¹ of the rock shaft, in accordance with the difference of their adding value.
According to the specification, Ludlum evidently had the idea that he could stop the adding gear H, while under the high rate of speed it would receive from a quick depression of a key, by jabbing the detent J between the fine spacing of the gear teeth shown in his drawing. But to those familiar with the possibility of such stop devices, its inoperativeness will be obvious; not that the principle properly applied would not work, for its application by Felt prior to that of Ludlum proved the possibilities of this method of gauging additive actuation.
The detent lever J, as shown in the drawings, is operated by the hinged plate D, through action of the key levers, as any one of them are depressed.
Under depression of a key, the hinged plate D, being carried down with it, engages the arm J³ of the detent and throws the tooth at its upper end into the teeth of the gear H.
The timing of the entry of the tooth of the detent is supposed to be gauged to enter the right tooth, but as the action of these parts is fast, slow or medium at the will of the operator, considerable time must be allowed for variation in the entry of the detent tooth, which requires space, as certain parts will fly ahead under the sudden impact they may receive from a quick stroke, where they would not under a slow stroke, but no allowance was provided for such contingency.
The means provided for the carry of the tens consist of the gears G⁹, meshing with the numeral wheel gears and the single gear tooth g⁹, attached to it, which, at each revolution of the lower wheel, as it passes from 9 to 0, engages the gear of the numeral wheel of higher denomination and was supposed to turn the higher gear one-tenth of a revolution, thus registering one greater.
On account of the Gears G⁹, of one order and the gear tooth g⁹, of another order operating on the same numeral wheel gear, the transfer gears are arranged alternately on separate shafts, one at the side and one below the numeral wheels.
The mechanical scheme disclosed in the Ludlum patent, to the unsophisticated may seem to be operative. But to those familiar with the Art of key-driven adding mechanism it will at once be obvious that even if the typewriter feature was constructed properly the possibility of correctly adding the items as they were printed was absolutely impossible.
Laying aside several other features of inoperativeness, obvious to those who know such mechanism, the reader, although not versed in the Art of key-driven adding mechanism, will observe from the preceding chapter, that the means provided for transferring the tens without any control for the numeral wheels against over-rotation, would make correct addition impossible.
The drawings and specification of the Ludlum patent disclose a mere dream and show that they were not copied from the make-up of an operative machine.
It was a daring scheme and one that none but a dreamer would undertake to construct in the method shown. There have in later years been some successful ten-key recording machines made and sold, but they were of a very different design and principle.
There have also been several adding attachments made and sold that could be adjusted to a regular commercial typewriter that are claimed to be dependable, but none of these machines were early enough to be claimed as the first operative recording-adding machine, or the first adding machine in which the principle used for the legible recording of the numerical items used in the machines of today may be found.