US2394637A - Accounting machine - Google Patents

Description

K. R. SCHNEIDER ACCOUNTING momma Filed May 24, 1941 Feb. 12, 1946.

FIGJ.

FIG. 2.

11 Sheets-Sheet 1 INVENTOR ATTORN EY 1946' K. R. SCHNEIDER 2,394,637

ACCOUNTING MACHINE Filed May 24, 1941 ll Sheets-Sheet 2 NE at Kb moo nuu uu wuu -huu Lbu nuu INVENTO R I M ATTO R N EY 1946' K. R. SCHNEIDER 2,394,637

ACCOUNTING MACHINE Filed May 24, 1941 ll Sheets-Sheet 3 FIGA: FIGS.

INVEN O AT'TORNEY 1946- K. R. SCHNEIDER ACCOUNTING MACHINE Filed May 24, 1941 ll Sheets-Sheet 4 R O T N E V m NGE 1946- K. R. SCHNEIDER ACCOUNTING MACHINE Filed May 24, 1941 11 Sheets-Sheet 5 F IG.8.

FIG. 9.

BY: gggi NToR w f LE Feb. 12, 1946.

K. R. SCHNEIDER ACCOUNTING MACHINE Filed May 24, 1941 11 Sheets- Sheet 6 camreaz. 40p T5 accu/nmnrs 6087A. Rs

466001044 75 855E? ENTIRE W4JNVENTOR Filed May 24, 1941 ll Sheets-Shegt 8 INVENTOR v ATTORNEY ACCOUNTING MACHINE Filed May 24, 1941 ll Sheets-Sheet 9 ATTORN EY FIG.

Feb. 12, E ER ACCOUNTING MACHINE Filed May 24, 1941 11 Sheets-Sheet 10 d lNV TOR S. gdfiiizw A'TToRNEY Feb. 12, 1946. K. R. SCHNEIDER ACCOUNTING MACHINE 1941 ll Sheets-Sheet 11 Filed May 24 MWR Patented m. 12, race UNITED STATES PATENT OFFICE I sooomm rlscm rm tyigiflewYcl-mmYcaoos-poratlonolliew "museum May :4, mu, Serial m. seam (OI. ass-so) Claims.

This invention relates to combined ypewriting and computing machines.

The primary object of the present invention is to provide a combined typewrlting and computing machine which is more flexible than prior art machines oi this class and capable oi operations which are either impossible of accomplishment in present commercial forms 01 such machines or require very complex mechanisms which must be mechanically operated, in part at least, by the carriage or the typewriting machine.

An object is to provide accumulating mechanism for a combined typewriting and computing machine in which the accumulation of amounts is not limited to accumulators of definite sizes but may be arbitrarily divided by the operator into as many accumulatorsas may be desired, and in which the number oi denominational orders is limited only by the total number of accumulator orders with which the machine is llil l fld- An object is to provide a combined typewriting and computing machine with what amounts to a single accumulator of large size which may be arbitrarily split into'accumulator sections, each section having any capacity desired by the operator.

Another object is to provide a novel accumulating mechanism for combined typewritlng and computing machines.

An object is to provide an accumulator and amount entering mechanism which is mechanically independent oi the typewriter keys and type bar operating mechanism so as to impose no additional load thereon.

An object is to provide a combined typewriting and computing machine in which the operations of column selection, addition, subtraction, and total printing may be eilected electrically under control of the keys and the typewriter carriage.

An object is to provide a novel automatic total taking means. i

An object is to provide an automatic total taking mechanism in which individual sections of the accumulator mechanism may be reset at will, either automatically or under manual control.

An obiect is to provide novel electrical transfer mechanism which is adapted for both addition and subtraction.

An object is to provide a combined typewritin and computing machine which is completely electrically controlled and operated and does not requirethe use of load inducing mechanical connectlons between the accumulating amount en- 55 cumulator clutch mechanism.

taking, and total taking mechanisms and the typewriter carriage or keys.

An object is to provide an electrically controlled amount entering and accumulating mechanism in which the operation of denominational selection is effected electrically by a relatively simple column-selecting switching device actuated by the carriage of the typewriter.

An object is to provide a computing mechanism which may be coupled to practically any standard typewriter, without substantial change in the machine, and without appreciably increasing the load upon the carriage or upon the keys oi the typewriter.

An object is to provide a combined typewrltini; and computing machine which is so constituted that the operator is relieved oi the work of operating the computing mechanism and in which the entire machine is controlled vby simple switches and keys and does not require any greater eiIort than is incidental to the actuation of keys to effect the operations of yp ng and computing oi numbers.

The resent invention has for one or its aims to provide a novel computing mechanism which overcomes the limitations to which the machines mentioned above are subjected.

Other objects oi the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings. which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a left side elevation of the machine.

Fig. 2 is a plan view.

Fig. Bis asectionon thelinel-I inI'lg.2 showing certain parts of the typewriter.

Fig. 4 is a rear view, partly broken away, of the column selector.

Fig. 5 is a front view, partly broken away and partly in section, oi the column selector.

Fig. 6 is a large scale vertical section on the line 0-8 c! Fig. 5.

Fig. 7 is a view of three adjacent denominational orders or the accumulating mechanism, showing one oi the orders in elevation and the other two in section.

Fig. 8 is a vertical section on the line 8-! in Fig. 7.

Fig. 9 is a vertical section on the line H in Fig. '1.

Fig. 10 is a large scale detail view of the ac- Fig. 11 is a section on the line ll--ll in Fig. 10.

Fig. 13 is a view of the main control switch unit.

Fig. 13 is a front view oi the plugboard.

Figs. 14a, 14b. 14c constitute a wiring diagram.

Fig. 15 shows how four accumulator Orders are Plugged for addition.

Fig. 16 shows how amounts printed in two separate amount columns may be added or subtracted in a group of orders constituting a single accumulator.

Fig. 1'! shows how two groups or orders may be plugged for addition in one group and subtraction in the other.

Fig. 18 is a timing chart for the switching mechanism actuated by the accumulator wheels.

The machine is shown in Figs. 1 and 2 as comprising a base 20 on the top of which is supported a typewriter 2|. It is preferred that a power operated typewriter be employed and accordingly there is shown in Figs. 1 and 2 the well known "Electromatic, also known as the- "International. It will be understood, however, that a manual machine or any other suitable form of power operated typewrter may be used if desired. Since the "Electromatic" typewriter is now well known in the art. only a brief description will be given of such parts as immediately cooperate with or control the mechan sm or circuits of the machine. If desired, the adding, subtracting, and total printing readout mechanism hereinafter to be described may be considered as an attachment for a typewriter and may be connected thereto by suitable cables, with the t pewriter 2| mounted on a desk. This is possible because the typewriter is only electrically connected with the adding, subtracting, and total readout mechanisms. Therefore. it need not be mounted upon the base 20. This feature makes it possible to use any typewriter having numeral keys and a carriage which is moved one letter space at a time to space the characters printed by type bars or other suitable printing instrumentality.

In Fig. 2, the numeral 22 designates a control board which is shown on a larger scale in Fig. 12 and comprises several switches which controcl adding, subtracting, total print'ng, and resetting operations. The numeral 23 (Figs. 1 and 2) designates a suitable plugboard which is shown on a larger scale in Fig. 13. This latter figure shows the arrangement of the plug sockets which are connected to the column selector, the accumulafor selecting relays, and certain parts of the circults involved in the transferring of units from one order to the other in addition and subtraction and also contains switches for controlling subtraction and resetting with respect to individual orders of the accumulating mechanism.

The purpose of the various switches and plug sockets shown in Figs. 12 and 13 will be brought out more clearly hereinafter with reference to the wiring diagram.

In order to adapt the typewriter for use with the present invention only minor alterations in its construction are required.

In Figs. 2 and .i, the numeral 24 designates the usual type bars of the Electromatic" pivotally mounted in the wire segment 25 which is mounted for case shifting movement in a well known way. The type bars actuate the usual escapement mechanism generally designated 25, through the medium of a universal bar 21 connected by a link 28 and an operating arm 29 to the escapement mechanism. The universal bar has a portion which is arcuate and extends into a slot formed in the segment 25 so as to be engaged by the type bars 24 when they are close to the platen and operated thereby whereby the escapement is actuated for each operation of a type bar.

The escapement 28 controls the letter spacing movement of the carriage it which is mounted on the rails 3| by suitable anti-friction bearings. As will be explained hereinafter, the carriage operates an electric column selector device which controls the entry of amounts into preselected denominational orders of the accumulating mechanism. Hereinafter the word "order" will be used generally to refer to the portion of an accumuiator which receives one digit of an amount and the orders will be distinguished from each other by referring to them as the units order, the tens order, etc.

The type bars 24 are operated in a well known way by cam units 32, 320, which are pivoted on the rods 33, by means of the links 34 connecting the cam units 32 to sublevers 35, the links 38, and toggles 31. The cam units 32, 32a cooperate with a power roller 38 which rotates continually in the direction oi the arrow in Fig. 3 while the machine is in use. The operation of the cam units is controlled by keys 3!, 40 of which the keys 39 control the cam units which operate the type bars other than the numeral type bars, while the keys ill control the cam units 3211 which operate the numeral type bars. The operation or the type bars by the cam units under control of the keys will not be described in detail because this is well known in the art. It will suillce to state here that whenever the number key Mi is depressed, the cam unit 3211 associated therewith is rocked clockwise in consequence of the cooperative relationship established between the cam carried thereby and the power roller 38. This effects operation of the associated numeral type bar by drawing down a link 34.

Although it is not believed to be absolutely necessary. it is preferred, as a safety measure, that the cams 32b have a single lobe in order to allow ample time for certain parts of the accumulating mechanism to operate before the next digit of an amount is printed in order to insure that the adding, subtracting, and total printing operations with respect to a single order of the accumulating mechanism will be completed before similar operations are commenced in the next denominational order. The com units 32, as is usually the case, are provided with double lobe cams which make one-half revolution for each operation of a key.

Associated with the key levers of the numeral keys 40 are ten operating solenoids designated KSO to KS9 (Figs. 3 and inclusive. These solenoids are selectively and successively energized during total printing operations to print totals automatically as will be made clear hereinafter at the proper point and will be termed the key selecting solenoids or simply key solenoids. The cam units 32a also operate certain contacts which control the amounts to be added and subtracted and for this purpose are provided with extensions 320 (Fig. 3) having disks 32d of insulating material thereon engaging one of the spring contact members supporting contacts designated "KCI to K09, inclusive in Fig. 140. These contacts will be referred to hereinafter as the key contacts and the numbers associated therewith indicate the digit which will be added or subtracted. Thus, when the numeral key controlling the one type bar is depressed, contacts KCI will be closed and cause one to be added in any order which is selected for operation.

The denominational orders are selected for addition, subtraction. and total printing by means of a column selector part of which is actuated by thecarriage in its letter spacing movements and is shown in detail in Figs. 4, 5, and 6. Secured to the top of the frame 2|! are two brackets 4i (Figs. 1 to 6, inclusive) on which is mounted a bar 42 of insulating material. This bar 42 contains molded therein inserts or segments Si to SI" of bronze, copper, or other current conducting material cf which there is one segment for every letter space position of the carriage. It will be convenient to assume that the typewriter 2| is an elite machine with a 12 inch carriage having a total travel of ten inches. Consequently there will be 120 of the segments required. In order to provide adequate insulation between the segments and to make them of generous width, the segments SI to SI2il are staggered as best shown in Figs. and 6. This makes it possible to make the segments SI to SI20 of the same width as the letter spaces of movement of the carriage and also minimize weakening of the bar 42 between the segments as might be the case if the spaces between the segments were very small.

The segments SI to Sl2li are provided with longitudinal holes receiving plugs 44 (Figs. 4 and 6) attached to the connecting wires 45. These connecting wires 45 may be provided with rubber finger pieces 46 to protect the operator from shock and for the same reason the rear part of the bar 42 has secured thereto an insulating strip 41 (Fig. 6) provided with holes slightly larger than the holes in the segments SI to SI2iI and registering therewith to prevent accidental contact with the segments. These features of construction also make it impossible to set up incorrect circuits by contact of metallic objects such as pins, paper clips, etc. which are likely to be dropped around ofilce machines.

Molded in the bar 42 is a common contact strip 48 (Figs. 5 and 6) which extends throughout the length of the bar 42 and is set flush with the bottom of an inner channel 42a, the side walls of which are partly formed by the plastic material from which the bar 42 is molded and partly by the sides of the right hand ends of segments Si to Sl20. The bar 42 is also formed with two confronting ribs 42b which act as guides for a block of insulating material 49 grooved to accommodate the ribs 42b. This block is T-shaped in cross section, as shown in Fig. 6, and has secured to the rear face thereof a metallic block 50 provided with three sockets receiving three contact plungers 5| which are urged against the bar 48 and against the sides of the segments 43 by suitable compression springs. Thus for each letter space position of the carriage, one of the segments SI to Sl2fl will be electrically connected to the bar 48 which acts as a common contact strip.

The block 43 is secured to an arm 53 mounted on the cross bar 54 (Figs. 1 and 3) of a. U-shaped bracket having its arms 54a secured to the side plates or the carriage 30. The arm 53 is located at substantially the midpoint of the bar 54 whereby the plungers 5| will electrically connect the segment SI (Fig. 4) to the bar 48 when the carriage is in the first column position and similarly connect the segment Sl20 to bar 48 when gm carriage is in the last or 120th column pool- With reference to Figs. 13, 14a, and MD, the segments BI to SI" are connected to plug lockets PSI, which provide a means for electrically connecting the accumulator selection relays to the column selector by means of plug wires for the purpose of selecting the order in which amounts are to be entered. There is a column selection relay for each order 01 the accumulating mechanism. Conveniently it may be assumed that an accumulating mechanism comprising 30 orders is provided requiring 30 column selector relays which may be designated RI, R2 R29, R30. In Figs. 14a and 14b only four denominational orders are shown including the column selector relays RI, R2, R29, R34. but it will be assumed that twenty-six similar accumulator orders whose relays are designated R3 to R28 intervene between the two parts of the wiring shown in Figs. 14a and 14b. Since the wiring would be merely a repetition of Figs. 14a and 14b, 9. showing of all the orders is omitted but the plugboard (Fig. 13) is shown with all the necessary switches and plug sockets for a column selector comprising 120 positions or columns and accumulating mechanism having thirty denominational orders. It will be understood that the number of denominational orders is purely arbitrary and merely involves providing the proper number of circuit sections shown in Figs. 14a and 14b between the broken vertical lines with accessory mechanical structure to be described hereinafter comprising clutch mechanism and commutators of novel form.

The relays RI to R30 (Figs. 14a, 141)) are connected to a common wir W4 which in turnis connected to the line wire WI, while the contact strip 48 is connected to the wire W1 which in turn is connected to the line wire W2. The relays RI to R3!) are individually connected to plug sockets PS2 (Figs. 13, 14a and 14b) whereby any relay, such as relay RI, may be connected by a plug wire to any of the segments SI to SI 20 by inserting the plug wire between the appropriate plug sockets PSI, PS2. For example, if it is desired to print numerals in column 1 of the work sheet and add the amounts printed in the first denominational order of the accumulator. a plug wire will be inserted between the plug socket PSI for the segment SI and the plug sockets PS2 for the relay RI. With this system of plugging, if the carriage is in the column 1 position, relay RI will be energized and will ren-' der the first order of the accumulating mechanism operative for adding or subtracting according to the setting of other switches in a manner to be made clear hereinafter.

As the carriage moves from right to left in the course of printing characters or multi-digit amounts, the relays Rl to R30 will be selected in succession according t the number and positlons or columns to which they are plugged. For example, if it were desired to add a six-digit number in the first six positions of the accumulating mechanism, relays Rl to R6 would be plugged to columns 1 to 6 by inserting plug wires as described above to connect the segments SI to S8 to the coils of the relays RI to R6. With this arrangement, th movement of the carriage in the letter spacing direction to print an amount comprising six digits or less would result in the denominational selection of the relays Rl to R6, the relay R6 corresponding in this case to the units order since it will be the last one to be energized, while the relay RI will correspond to the hundreds of thousandths order. In substance, therefore, the insertion of a plug wire in a selected one of the plug sockets PSI and .n a plug socket PS2 will render the accumulating mechanism operative to add or subtract with respect to a particular column on the work sheet and order of the accumulating mechanism.

The accumulating mechanism is quite simple and comprises a plurality of accumulator sections or orders, each of which includes a series of adding magnets, a differential clutch, a commutator rotated variable extents under control of the clutch according to the amount to be added and subtracted. and a series of cam operated contacts which control subtraction and for other purposes. These accumulator orders exist as independent units which may be rendered operative and inoperative at will and may be combined or grouped in any desired way irrespective of their specific mechanical arrangement in the machine. The units are fully mechanically independent of each other and may be plugged in various preselected combinations at the will of the operator.

The accumulating mechanism may be housed in a compartment 56 (Fig. 1) supported by the base 20 and includes one or more shafts 51 (Figs. 7 to 10, inclusive) rotated continually in the direction of the arrows in these figures by a suitable motor not shown. The number and arrangement of the shafts 51 are purely arbitrary and are governed solely by considerations of machine capacity, compactness of spacing, nd physical size of the compartment 56. It will be convenlent to assume that there are thirty accumulator sections or orders, each including its own clutch and associated commutator and cam operated contacts. Also associated with each accumulator order is one of the relays Rl to RM).

In Fig. 7 are shown three different accumulator orders of which the one at the right is shown in side elevation while the one at the extreme left is shown in vertical section. The one in the middle is shown partly in section to more clearly indicate the construction of the clutch mechanism. As will be seen at the left in Fig. 7 and in Figs. 8 and 10, the shaft 51 is formed with ratchet teeth 51a designed to cooperate with a tooth 58a (Fig. 10) on a clutch dog 58 pivoted at 59 on a ten-tooth ratchet 50 loosely joumaled on the shaft 51 adjacent the teeth 51a. The ratchet 60 is formed with a flange 50a. acting as asupport and guide for a tension spring 6| anchored to the end of the clutch dog 58 and the spring GI constantly tends to rotate the dog 58 in a counterclockwise direction to engage the tooth 58a with one of the teeth 51a. There are ten teeth in the ratchet 50 representing numerals to 9, inclusive. This ratchet 6|) and other parts secured thereto may be considered an accumulator wheel and there is one for each of the thirty orders.

The ratchet 58 is allowed to rotate from 1 to 9 increments to add amounts by controlling the length of time the teeth 58a remain in engagement with the ratchet teeth 51d. For the purpose of controlling the rotation 01 the ratchet so. there is provided a group of ten magnets for each order, designated M0 to M9, but the designation of these adding magnets in respect to the numerical sufiix need not have any fixed relation to the amount actually added, since the startin point of any single addition in any order will be constantly shifted according to the amounts previously added in such order. However, it will be convenient to assume that the magnet M0 corresponds to the zero position and, through its detent mechanism to be described hereinafter, holds the corresponding ratchet Gil against forward rotation when the commutator and cam mechanism associated with such ratchet are standing in the zero position. With this assumption in mind, the initial energization of the adding magnet Mi will cause the addition of a unit; the magnet M2, two units; magnet M3, three units, etc., but after the initial entry in the accumulating mechanism, the numerical suflixes of the magnets Mi. Mi, etc., will lose their significance so far as the actual digit entered is concerned. For example, if one unit is added by energizing the adding magnet Ml, the commutator and cam assembly associated with the ratchet ill will rotate one unit and if another unit is to be added. magnet M! will be energized instead of magnet Ml.

It is desired to make clear at this point that, while the numeral suilixes of the designations of the magnets Mil to M9 do not always have any significance in entering amounts and, from that standpoint only, are purely arbitrary, the designations do have a definite relation to the digits represented by the positions of the accumulator wheels. Thus magnet M0 and its detent stop the wheel in zero position, magnet Mi stops the wheel in the 1" position, and so on up to magnet M! which stops the wheel in the 9 position, as will be explained hereinafter. Furthermore, magnets Mil have the special function, when the accumulator is reset, of stopping the wheels at zero, hence magnets M0 will be referred to hereinafter as zero magnets. It will be seen, therefore, that the magnets Mil to M5 correspond both in respect to numerical designation and in respect to the position of clutch dogs 58 in relation thereto, to the values of the numeral keys ill. This correspondence will be more clearly explained or emphasized hereinafter at appropriate points in the description.

The magnets Mil to M9 of each group are mounted on brackets 62 (Figs. 7, 8, and 10) secured to partition plates 63 fastened in spaced relation on a suitable frame plate 55. Associated with each magnet and pivoted at 830 on the plate 63 adjacent each magnet is a clutch detent lever 65 to which is secured an armature 66 cooperating with one of the associated magnets. Springs 61 anchored to the detent levers 55 and to pins on the plate 63 tend to rock the detent levers in a counterclockwise direction. The end of each detent lever 65 opposite the armature G8 is shaped like a fish hook as most clearly shown in Fig. 10 and cooperates with a retaining ring 58 which is rotatably mounted, as best shown in Fig. 11, on rollers 59 which ride in a groove formed in the retaining ring 68. The rollers 59 are rotatably mounted on studs 10 and are spaced from the plate 63 by collars H, the studs 'Iil being shouldered to clamp the collars Ii to the plate 53 and allow free rotation of the rollers 69. Springs 12 (Fig. 10), anchored to pins on the retaining ring 68 and pins carried by the plate 63, respectively, urge the retaining ring 58 for each group of detent levers G5 in a clockwise direction but rotation of the retaining ring is limited by engagement of latch lugs 58a formed in such ring with the inside portion of the fish hook shaped end of at least one detent lever 65 as shown by the one for magnet Mli in Fig. 10.

The detent levers G5 and the lugs 68:: are "so shaped that the lugs We act as latches to prevent retraction oi the detent lever 68 by its spring l'l whenever it has been operated by a magnet as illustrated by the case of the magnet MII and the associated detent lever it in Fig. 10. The lugs Illa are shaped with a cam surface "b which cooperates with a cam surface Na in the fish hook shaped end of the detent lever 85 so that energization of any magnet except the one whose detent lever BI has a latching relationship with the retaining ring 68 will cause the retaining ring to be rotated in a counterclockwise direction a slight extent to release the previously operated detent lever 65. In the released position the detent levers I! are held by the spring 81 against stop Pins II, as shown by the lever 65 for the magnet M9 in Fig. 10.

The fish hook shaped ends of the detent levers II, when in the position shown by the lever for adding magnet Mil in Fig. 10, are clear of a stop portion 58b on the clutch dog 58, but when the detent lever is latched in the position shown by the one for the magnet Ml'in Fig. 10, the dog 58 is restrained against movement to bring its tooth Ila into engagement with the tooth Bid on the shaft 51. In order to prevent back rotation of the ratchet 80 under the influence of the spring 6|, there is provided a detent l4 pivoted on a stud carried by plate 63 and urged into engagement with the ratchet 50 by a spring H.

In order to explain the operation of the diii'erential clutch, it will be assumed that the ratchet wheel 80 stands in zero position which is determined by the detent lever 85 for the adding magnet MD as shown in Fig. 10 and that it is desired to add 9. Ir a circuit is closed through magnet M9, the cam surface 850 on the hook shaped end of the lever 65 for magnet M9, by cooperation with the cam surface the associated lug 88a in the retaining ring 68, will cause such retaining ring to be rotated slightly in a counterclockwise direction. This will result in the release of the detent lever'tl for the adding magnet M0 and will result in latching of the detent lever 65 for magnet M9 in a position similar to the position of detent lever BI for magnet Mil now shown in Fig. 10. The release of the latter detent lever will allow the spring II to rock the clutch dog 58 in a counterclockwise direction to engage the tooth 58a thereon with one of the teeth 51a in the continually rotating shaft I1. Consequently the ratchet 60 will be coupled to the shaft 51 and rotate therewith until the end Nb of the dog It will engage the detent lever 05 of the magnet M. Thi will force the tooth Ida in dog Ill out of engagement with teeth 51a and stop rotation of the ratchet 60 after exactly nine-tenths of a revolution of such ratchet. The pawl M will drop behind one of the teeth in the ratchet Bil and prevent rebound of such ratchet and clockwise rotation thereof after the dog It has been disengaged from the teeth 51. Had the adding magnet M8, for example, been energized instead of the magnet M9, the ratchet 6|! would be stopped after six-tenths of a revolution. It will be seen that the position of dog 58 may be used as a basis for "reading the amount standing on the accumulator, considering the detent for magnet MD as the 0" position, the detent for magnet MI as the 1" position, and so on.

The ratchet 60 drives a commutator and cam switch assembly which controls the energization of the adding magnets Mil to M9 according to the amount to be added and according to the position oi the ratchet I0, and the transfer from one order to the next. It has been assumed that the magnet Ml corresponds to both the zero position of the accumulator and the point of beginning addition on the ratchet wheel for sake of simplicity in explaining the operation of the clutch mechanism. The point at which addition actually commences in each case will depend upon the point at which the ratchet wheel ill stopped after the last operation. However, provision must be made for energizing the first, second, third, etc. magnets from that point according to the amount to be added. In other words, the reference point for selection of the magnets M0 to M9 will vary from adding cycle to adding cycle and for this reason it is impossible to designate the magnets M0 to M9 to truly represent the values added in each case.

To eilect the proper selection of the magnets for addition and subtraction, each ratchet 60 is provided with a commutator generally designated 18 in Figs. 7, 14a. and 14b having ten conducting segments with which cooperate ten brushes designated Bll to B9 in Figs. 9, 14a, and 141: which are mounted in an insulating frame I" secured to the plate 63. On account of lack of space for reference numerals only the end brushes are designated in Figs. 14a and 14b. As is clearly shown in Figs. 14a and 14b, the brushes Bl to B8 are connected to the adding magnets Ml to M9 respectiveiy and, when the ratchet wheel 60 stands in the zero position, the brush B0 rests upon the zero segment of the commutator 18. If now the value 9 is added as explained above, the zero segment for commutator It will be rotated until the brush B9 of magnet M9 rests upon the zero segment.

The selective energization of the magnet M0 to M9 takes place with reference to the zero segment of the commutator 16 rather than with reference to the magnet Mil. In other words, the first, second, third, etc., adding magnets to the right (Fig. 14a) of the particular one opposite which the zero segment happens to be located. will be energized according to the value to be added. For example, supposing the addition started at zero, the value 6 had been added. the zero segment is underneath the brush BB, and it is desired to add 2: the magnet M8 will be energized which is, of course. the second magnet to the right from the magnet Mil (Fig. or counterclockwise (Figs 8) opposite which the zero segment came to rest after adding 6.

Each ratchet til (Fig. '1) is part of an end ring which is screwed on the right hand end or a tube ii and on the left hand end or such tube is screwed another and ring 18. The ratchet It. the end ring 18 and the ends of the tube 11 are formed as the ball races of a bearing including balls 19 which ride in grooves formed in the shaft 51. Concentric with each tube i1 is an insulating tube 80 on which is mounted a series of cams ll, preferably made of insulating material, which separate conducting rings 82. The rings 82 are individually connected to the segments of the commutator l6. Secured to the plate 83 is a brush carrier block 83 (Figs. 7 and 9) provided with slots in which are secured in a well known way brushes designated the BCI to 309 respectively (Figs. 7, 14a, and 14b). The numerical sufllxes in the designations BCI to BC! indicate the value to be added when a circuit is to be cstablished to a magnet M0 to M9 by means oithe keys KCI to KCB.

' The brushes BCII to B09 inclusive for each order of the accumulating mechanism are connected to normally open contacts of one or the relays Ri, R2 R28, R29. These contacts are designated D0 to D! respectively and are also conhaving ten wires which connect in common all of the similarly designated D contacts of the relays RI to R". This adding cable leads to the normally closed contacts A of a subtraction relay SR (Fig. 140). The contacts A of the relay SR are connected individually to the key controlled contacts KCi to K09. inclusive. Normally the subtraction relay SR is deenergized whereby the closure of any selected key contacts KCI to KC! according to the amount to be added, will cause a circuit to be established to one of the magnets MI to M9 or an order of the accumulating mechanism in which the column selection relay RI, RI, etc., happens to be energized, this circuit being established through the appropriate wire of the cable AC, the proper D contact of the relay, the appropriate ones of brushes BCI to 309 and BI to B9, and the corresponding magnets MI to MI. The tracing of this circuit will be more clearly explained hereinafter in conjunction with the description of the operation of the machine.

As shown in Fig. 9, each or the twelve cams 8| operates a pair of contacts which pairs or contacts are mounted on a block 83a and are designated ATCI ATCI, STC, and CCi to CC! in Figs. 7, 14a, and 14!).

Contacts CCI to CC! are connected to the wires of the subtracting cable SC in such fashion that all contacts CCI are connected in common through the 1" wire oi. such cable to the C contacts of relay SR corresponding to the contacts KCI; CC! to C contacts R 2; C03 to C Eontacts K01, etc. The B contacts of relay SR are connected to the wires of cable AC complementary to the A contacts of such relay, according to the tens complements of the values represented by keys KCI to K09. For example, if a number is to be subtracted, relay SR will be energized in a manner to be explained later, then closure of contacts KCI, for example, will set up two circuits, one through the 9 wire of cable AC to brush E09 by way of contacts B, and the other to contacts CCI by way oi the C contacts of relay SR and the "1 wire of cable SC. The "9 key contacts K69 has exactly the opposite effect. The actual additions which take place in the accumulator order rendered effective by energizetion of a relay RI, R2, etc., is denoted by the numeral suflixes I to 9 in the reference numerals KCI to KC9, BCI -to 309, DI to D9, and CCI to C9. The small numerals 1 to 9 in Fig. 14c adjacent the contacts A, B, C of relay SR also refer to the numbers actually added whether the true number or tens complement.

The cam contacts are so timed (Fig. 18) that the contacts ATCI are closed momentarily when the ratchet 60 (Fig. is turned from the "9 position to the 0 position in the process or adding; contacts ATCI are closed only at 9"; while the contacts STC are closed only at the 0 position or the ratchet for the purpose of controlling transfer operations during subtraction. Contacts CCI to CC! are timed so that all are closed at the zero position but are opened progressively as shown in Fig. 18. For example, when the ratchet ill moves from "0 to i," the contacts CCI open, when the ratchet moves to 2 contacts CCI open, etc. The purpose oi this mode of opera- -tion is to cause a subtraction transfer to take place only when the ratchet SI of a particular order is standing at a value lower than the tens complement of the amount to be subtracted. For instance, it the position oi the ratchet 80 of any order in which a subtraction is to occur indicates nected to an adding cable designated AC and 6" and 5" is to be subtracted, then the closure of a circuit through the contacts CC! cannot be effected since the contacts CCI to CC! are open and a transfer cannot take place. This will be made clear hereinafter in describing the general operation or the machine in reference to particular examples.

In order to illustrate the process of addition and subtraction, it will be assumed that the four accumulator orders shown in Figs. 14a. and 14!: comprise a single accumulator and that this accumulator is to be operative with respect to an amount column including space columns 12 to 15, inclusive. In order to render these four orders operative for a simple case of subtraction and addition, the plug sockets PSI (Fig. 13) for columns 12 to 15 will be connected to plug sockets PS2 for accumulator orders 1, 2, 29, and 30 by means of suitable plug wires as in Fig. 15. with this arrangement, the relays RI, R2, R2! and R30 will be energized successively in the order named when the carriage moves from column 11 to column 15. Any selected one of the relays RI, R2, R29, R30 will remain energized during the periods in which any of the numeral type bars are being operated under control 0! the numeral keys. Plug wires are also inserted between socket plug PS5 and the "out" plug socket PS4 for order 1 of the accumulating mechanism. A plug wire is inserted between the in" plug socket PS3 for accumulator order 1 and the plug socket PS4 for order 2, also between plug socket PS3 for order 2 and PS6 for order 29. A plug wire is inserted between PS8 for order 29 and PS! for order 30. Plug wires are inserted between plug sockets PS6, PS1 for orders 1, 29, and 30 as described above except that the plug wire to PSI is omitted. The subtraction transfer split plug sockets PS8, PS9 are plugged in the same way as the adding transfer splits PS6, PS1.

The effect of this plugging is shown in Figs. 14a and 14b by solid lines between the respective plug sockets. It will be understood that the individual subtract switches ISI, 1S2, IS", and 1830; the individual reset switches IRSI, IRSI, IRS, AND IRS; the total switch T8, the manual reset switch MRS; and the reset switch RS are all open. The non-accumulate switch NAS is closed to effect addition. Switch SAS remains in neutral position as in Fig. 14c.

The carriage of the typewriter is moved to column 12 in any desired way as by hand, or by means of either the space bar or tabulating mechanism. This causes the relay RI (Fig. 14a) to be energized by a circuit from line wire WI, wire W4, the coil 01' relay RI, the plug wire between plug sockets PSI, PS2 for order 1; the column selector contact segment SI: for column 12, the contact elements iii and the contact bar 48, and wires W1 and W23, to line wire W2. The contacts A, B, D0 to D9. and E oi relay Ri close and contacts C open.

Assume the value Ii is to be added In accumulator order 1 which, in this case, will be the thousands order of the accumulator. The "6" key 40 of the typewriter is now depressed thereby causing the cam unit 32a associated with the "6" key (Fig. 3) to operate the contacts KC! and at the same time print the numeral "6" in column 12 on the work sheet. The closure of contacts KS8 associated with the 6" key (Fig. 14c) establishes an adding circuit as iollows: line wire WI, contacts A of the total relay Til-2 (Fig. the non-add switch NAS, wire WII, contacts K08, contacts A of the subtraction of relay BR,

the "6" wire or the adding cable AC, the contacts D5 of the relay RI (Fig. 14a), the brush BCB, the 6" segment of. commutator 18, adding magnet M6, the common wire WIS, the plug wire between plug sockets PS4 for order 1 and PS5,

wire WI, contacts C of total relay TRI (Fig. 14c) and wire WI 5, to the line wire W2.

Energization of the magnet M6 causes the ratchet ill associated with order 1 of the accumulating mechanism to turn six-tenths of a revolution, thereby moving the zero segment of the commutator connected thereto to a point opposite the magnet M6. Incidental to the printing of the numeral 6 in column 12 of the work sheet, the escapement mechanism 26 (Fig. 3) will be operated and the carriage will escape to column 13. This cycle of events is repeated when the next three digits are typed. The effect of rotating the commutator each time a digit is added, as explained above, is to shift the zero spot as many units as the amount to be added and to establish a new starting point for the addition of a subsequent digit of another amount. Thus if after adding 6 in order 1 it is desired to add 5, the fifth magnet from magnet M6 in a counterclockwise direction (Fig. 8) or Ml will be energized.

Assuming that the accumulator mechanism stands at zero at the start, the addition of say a four-digit number in the four accumulator orders shown in Figs. 14a, and 1411, as plugged in Fig. 15, will not require a transfer operation. The transfer of a unit when any ratchet wheel 60 turns through the zero position is effected electrically in the following manner: Let it be assumed that the value 1918 has been accumulated on the four orders or orders shown in Figs. 14:: and 14b, and that the amount 36 is to be added. The carriage is moved to space column 12 as before and the space bar depressed twice or if it is desired to print the zeros, the zero type bar may be caused to be operated by pressing the zero key twice. Since there are no electrical connections involving the zero key, no circuit will be established when the zeros are printed but the carriage will merely space to column 14 and energize the relay R29. The 3" key is now depressed and the value 3 will be added in order 29 of the accumulating mechanism. This rotates the ratchet 60 corresponding to order 29 to the zero position, thereby causing the adding transfer contacts ATCI to close in order 29. This establishes an adding transfer circuit as follows: line wire WI, contacts A of relay TR2 (Fig. 140) switch NAS, wire W28, contacts D of relay SR, wire W5, contacts B of relay R29 (Fig. 14b) contacts ATCI for order 29, the plug wire between plug sockets PS1 for order 29 and PS6 for order 2, the brush BCI for order 2, a wire W32 in total cable TC, contacts B of relay TRi (Fig. 140) another wire W32, magnet M (Fig. 14a) the plug wire between plug sockets PS for order 2 and PS3 for order 1, contacts C of relay Ri, the plug wire between plug sockets PS4 for order 1 and PS5, wire W8 (Figs. 14a to 140), contacts C of relay TRI (Fig. 14c), and wire Wli, to line wire W2. This causes a unit to be added in order 2 (controlled by relay R2) of the accumulating mechanism, thereby causing the ratchet 60 associated therewith to move to the zero position, since the ratchet wheel 60 for order 2 formerly stood at the "9" position. Because of this fact. the contacts ATC2 for order 2 are in closed condition when the circuit through contacts ATCI for order 29 is closed, thereby estmblishing a parallel circuit to the magnet M2 for order 1, this circuit being traced from the plug socket PS6 for order 2. contacts ATC! for order 2. the plug wire between plug sockets PS6 or order 1 and PS1 for order 2, the brush IBCI for order 1; the magnet M2 to order 1, bearing in mind that the zero segment of order 1 is opposite the magnet Ml, to plug socket PS4 for order 1. This causes a unit to be added simultaneously in the first and second denominational orders of the accumulator. The contacts ATC2 for any order which stands at 9" anticipate the need for a transfer to the next higher order and enables the transfer to be eifective simultaneously with a transfer to the intermediate order. In the event that all of the accumulator wheels of higher order stood at 9, the same parallel circuits would be set up through all of the higher orders to energize all of the magnets Ml for such orders. The amount 2008 will stand on the accumulator at the end of these' operations.

The carriage will now move to space column 15 and the "6 key 40 will be depressed thereby closing contacts KCG. Similar circuits will be established through the magnet M4 for order 30, since the zero segment is opposite the magnet M8, and an adding transfer circuit through contacts ATCI for order 30 to magnet MI of order 29. as traced above. This circuit is closed when the second unit of the 6 has been added in column 30, causing ratchet 6B for this column to pass through the zero position, defined by the detent B! for the magnet Ml). Since contacts ATC2 for orders 2 and 29 are open when the 6" key is depressed, both ratchets Gil for these orders being in rare position, only one transfer circuit is established.

The machine may be conditioned for subtraction in two different ways, one automatic and the other manual. The denominational relays Rl to R30 each are provided with contacts E (Figs. 14a and 14b) for causing subtraction to take place automatically when the corresponding individual subtract switches designated ISI to I830 are closed (see Fig. 13 also) or in Sub. position. Each of the switches ISI to ISM is in series with one of the contacts E between wires W3, W8 of which the wire W8 i connected to the line wire W2 through the contacts C or the total relay TRI, while the wire W8 is connected to line wire WI through the contacts SASI of subtractadd switch SAS, wire W20, the coil of relay SR, wire W2l, switch NAS, and contacts A of total relay 1R2. Switch SAS is a well-known form having three positions. When in neutral position as in Fig. 146. contacts SASI are closed and SAS2 are open. It is evident, therefore, that whenever the carriage is in a position to select one of the relays Rl to R30, and switch SAS is in neutral position, the closure of the contacts E associated with the selected relay will close a circuit which will cause the energization oi the relay SR and may be traced as follows, assuming for convenience that the relay R30 (Fig. 14b) is energized: Line wire WI (Fig. contacts A of relay TR2, switch NAS, wire W2i, relay SR, wire W20, contacts SASI, wire W2, the individual reset switch, ISIII (Fig. 14b), contact E of relay R30, wire W8, contacts 0 of relay TRi (Fig. 140),

the adding cable AC to the contacts B of relay SR are such that the circuits to the adding cable are inverted according to the tens complement oi the numeral values represented by the numeral keys. For example, the contacts K! in stead of closing a circuit to the 1" wire oi the adding cable AC, now closes a circuit to the 9" wire or the adding cable. However, the connections of contacts C of relay SR to the subtracting cable SC are not inverted whereby the contacts KCI connect the wire WII to the 1" wire of cable SC. The subtracting cable SC is provided with a branch for each order oi the accumulating mechanism leading to one of the contacts CCI to 0C9. For example, the 1" wire B connected to contacts CCI, the "2 wire to contacts 002, etc. It will be remembered that each group of the contacts CCI to CC! opens in succession as the ratchet 80 with which they are associated turns from the zero to the 9" position. For example, contacts CCI will be opened and contacts (202 to CC! closed when the ratchet wheel is in the 1 position.

When it is desired to subtract automatically under control of the carriage of the typewriter, the individual subtract switches ISI to ISM are selectively set manually (Fig. 13) to the closed or Sub. position for the particular orders or groups of orders of the accumulating mechanism which will correspond to an amount column in which subtraction is to be effected, it being assumed that a positive number, such as a balance has already been entered in the selected group of orders by an adding operation which may be performed under manual control by means of the switch SAS. When it is desired to add in any order automatically, the switches 18! to I830 for the selected orders or groups of orders will be left in the open or "Add' position but it will, nevertheless, still be possible to subtract in such orders under manual control by setting the switch SAS to Add" position. Switch SAS, in Add" position (Fig. 140), opens contacts SASI to prevent automatic energization of the subtraction relay SR and, in Sub." position, closes contacts SASZ to energize relay SR to enable subtractions. This makes it possible to correct errors and add or subtract under special conditions where the normal operation would be the reverse.

If a group of orders of the accumulating mechanism associated with a particular amount column on a work sheet have been conditioned for addition by inserting plug wires between the proper plug sockets PSI, PS2, and it is desired to subtract one item only where otherwlseaddition would take place, the switch SAS (Figs. 12 and 14) may be moved downwardly in Fig. 12 or to the right in Fig. Me to the subtract position. This closes contacts SAS2 and energizes the subtract relay SR by a circuit similar to the first part of the one traced above except that the contacts SASI shunt the open switches ISI to 1830 whereby the relay SR is directly energized regardless of the condition of the individual subtract switches IS-l to 1830.

Under certain circumstances it may not be desired to either add or subtract amounts printed in a particular amount column where either addition or subtraction would normally take place automatically. Accordingly, the non-accumulate switch NAS may be opened and prevents any circuits from being established by means of the key contacts KCI to KCO. switch NAB also will deenergiae the subtract relay The operation 01 88 it it is being maintained in energized condition as consequence 02 a selection by one of the column selection relays Rl to R30.

A subtraction operation will now be described, assuming that the four orders shown in Fi s. 14a and 14b have been plugged as described above with reference to Fig. 15 for addition and that the switches I51, 152, I329, 1830 have been closed to cause subtraction to take place automatically whenever the carriage of the typewriting machine is positioned to select the relays RI, R2, R28, R". The combined plugging for both addition and subtraction transfers is shown in Fig. 15. With this plugging the machine will normally automatically subtract in the first, second, twenty-ninth and thirtieth orders or the accumulating mechanism operating as a single accumulater of tour orders for amounts typed in a column oi the work sheet including space columns 12 to 15 of the typewriter carriage.

It will be assumed that the four ratchets 8B associated with the four orders selected have positions representing the amount 0060 and that it is desired to subtract 0028. The operator positions the carriage to space column H which causes the relay R29 to be energized in the manner described above, thereby closing its contacts E and causing the energization of the subtraction relay SR. Since the ratchet 60 for the 29th order is now standing at 6, the contacts CCI to CCB, inclusive will all be open while contacts CC! to CC! will be closed. Also the contacts ATCI ATC2, and STC will all be open.

The operator now presses the "2 key which, through operation of the cam unit 32a associated with the "2 key, causes the 2 type bar to be operated and also causes the contacts KC! to close. This potentially establishes two separate circuits to the 29th order of the accumulating mechanism. The first circuit causes the value 8. the tens complement of 2, to be added and is traced as iollows: line wire Wi (Fig. contacts A of relay TRI, switch NAS, wire W2l, contacts K02, contacts B of relay SR, the "8" wire of adding cable AC, contacts D8 of relay R29, (Fig. MD) the brush BCB and the common ring 82 associated therewith, the adding magnet M4 for the 29th order because the zero segment of commutator I5 is now opposite the magnet M8, and thence to line wire W2 as explained above. This causes the ratchet B0 to be rotated far enough to carry the zero segment to a point opposite the magnet M4. No adding transfer circuit is closed however, although the ratchet wheel (ill of the 29th order has turned to zero and closed the contacts ATCI, because the energization of the subtract relay SR has opened contacts D of this relay to prevent any circuits from being established from the wire W5 through the contacts B of relay R29 to the contacts ATCl. Thus the ratchet ill for the 29th order rotates,as if 8 and 6 had been added to give 14 but the transfer of the unit is eliminated.

The second circuit which might be established by contacts KC2 through contacts C of relay SR cannot be made in the present case because the contacts 002 (which are now connected to contacts K02) are open in the beginning of this case because of the fact that the ratchet Gil stood at "6 in the beginning with all contacts CCI to CO8 open. Thus at the end of the operation of adding 8, the complement of 2, the result is the same as if 20 had been subtracted from 60 and the 29th and 30th orders now retain the value 40. The circuit established by the contacts K02 is mo- 'subtrahend so that the result was positive.

mentar and will not be held long enough for the second circuit to be established through any or the other contacts CCI to CC9 in the event that one closes as a result of the addition. As a result of typing the value 2 in space column 14 on the work sheet, the carriage will escape to space column 15, thereby selecting the relay R30. The relay SR. is momentarily deenergized but is reenergized in consequence of the fact that the switch 1830 is closed.

The operator now depresses the "8" key which can, in this case, establish two circuits through the contacts K08 because the ratchet wheel 60 for the 30th order now stands at zero with all of the contacts CCI to CO closed. The first circuit is traced as described above through the contacts KCI to the "2" wire of the adding cable AC and through the magnet M2 for the 30th order, since the zero segment or commutator 18 for this order is at the zero position, that is, opposite magnet Ml. As a result of pressing the 8 key, tne value 2 will be added in the 80th order.

The second or subtraction transfer circuit is established from the contacts KCB, through contacts O oi! relay SR (Fig. 14c) the "8" wire of the subtract cable SC, contacts CC! for the 30th order. contacts A 01' relay R30 (Fig. 14b), the plug wire between the "out" plug socket PS9 for such order and the "in" plug socket PS8 for the 29th order, the brush BC! for the 29th order, the brush B3 and magnet Ml for the 29th order, and wires WI and the plug wires between the plug sockets PS3, PS4 and PS4, PS5 for the 1st and 2nd orders, wire WI, contacts C of relay TRI, and wire Wit, to line wire W2. Since the ratchet wheel 00 of the 29th order initially stood at 4, the contacts 8T0 will be open and a branch subtraction transfer circuit cannot be established to the second order. However, the energization oi the magnet Ml causes the value 9 to be added in the 29th order, whereby the ratchet wheel for this order will turn to the value 3 while the ratchet wheel SI for the 30th order will turn to the value 2. Thus, at the end of the second adding cycle, the accumulator will stand at 0032. No units carry can be effected in the normal way because contacts D oi relay SR are open, preventing the contacts ATCI from having any eilect. The contacts ATC2 cannot have any eilect because they, in turn, depend upon the operation of the contacts ATCI.

It will be noted from the foregoing that subtraction is effected by always adding the tens complement of the digit to be subtracted in the order of the accumulator in which subtraction is eilected. When the actual value to be subtracted is less than the amount standing on the accumulate: a transfer of the tens complement of l to the next order on the left is not possible because 01' the action of the contacts CCI to CO0, but where the amount to be actually subtracted is greater than the amount standing on the accumulator order, the tensvcomplement is transferred to the next adjacent order on the left through one oi the contacts CCI to C09.

In the process of subtraction there is one condition which must be met by the subtraction transfer mechanism which the contacts STC are provided to meet. In the above illustration, the minuend was presumed to be greater than the It might happen, however, that in the tabulation of a long column of figures, the amount standing on the accumulator might temporarily become negative or exactly balance. In other words, the

amount standing on the accumulator, or minuend, might be zero or less than the amount to be subtracted, or subtrahend. This also might be true at the end 01' a tabulation oi debit and credit items in which the total or added debit items might be less than the total oi. the credit items subtracted.

Let it be assumed that the value 0060 stands on the accumulator as in the above case but that the value 0082 is to be subtracted instead oi 0028. The operator positions the carriage to column 14 and presses the 8" key. This will cause the value 2 to be added in the 29th order of the accumulator by circuits similar to the one traced above. Since the ratchet 60 for the 29th order initially stood at 6, the contacts CCI to CCI will all be open and contacts 001, CCI, C09 are closed so that a subtractive transfer through contacts A of relay R29 to the brush B09 oi the second order can be affected by the second circuit 01' which the contacts KCll are capable of establishing. Furthermore, the ratchets 60 for the first and second Orders both stand at zero and their contacts STC are closed. A circuit will be set up from contacts K08 through the contacts CO0 for the 29th order through contacts A of relay R29 to the in" plug socket PS8 for the second order. Since the contacts STC are closed for this order and the first order, two parallel circuits will be established through the magnets M9 for these orders, thereby causing the ratchets 60 for the first and second orders to rotate to 9. As a result, the amount 9980 will stand on the accumulator after the first digit of 82 has been subtracted. This is the complement of 20, the diflerence between and 60. The carriage, of course, will space to the 15th column space and the operator will depress the 2 key, 8 to be actually added in the 30th order and, since the 30th order ratchet 60 stands at zero, a transfer of 9 to the 29th Order will occur through the contacts 002 of the 30th order as described above but, since the first and second order wheels now stand at 9, this transfer 01' 9 will be limited to the 29th order. As a result, the accumulator will re ister 9978. This will be found to be the complement or 22 which is the algebraic difference between 60 and 82. Thus, whenever a total is printed which contains a 9 in the highest order denominationally oi the accumulator, it is an indication that the accumulator contains a negative balance stored as the complement of the balance.

The above mode of operation also takes Place with respect to intervening orders which may happen to have a zero standing on them between the highest digit of an amount and the lowest. For example, in subtracting 9 from 108, a unit will be added in the 30th order and the 9 will be transferred to the 29th order as explained above through the operation of the contacts CCO. Since the ratchet 50 for the 29th order stands at zero, its contacts STC will be closed. thereby setting up the branch circuit to the 9 magnet of the second order to cause a 9 to be added in the second order also. The second order, however, stands at l and its contacts STC are open whereby the transfer of 9's will be limited to the second and 29th orders. The eflect. therefore, of subtracting 9 from 108 is to add the value 991 to 108, yielding the result 099, it being remembered that the normal adding transfer is disabled, whereby a unit cannot be transferred to the first order in consequence of adding 900 to 100.

In Fig. 16 there is shown a modification of plugg ng to enable addition and subtraction to be thereby causing the value'

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