US1609206A

US1609206A - best available cop

Info

Publication number: US1609206A
Authority: US
Publication date: 1926-11-30
Anticipated expiration: 1943-11-30

Description

Nov. 30 1926.

BEST AVAILABLE com M. SAMBURG ET AL COMPUTING MACHINE O i Filed Dec. 16, 1920 mlw 8 Sheets-Sheet l ung $1 heiz flttomm wuwbow Maurine k/nhzr Jalzar (1170M Hug/a BEST AVASLABLE 6GP Nov. 30 1926.,

M. SAMBURG ET AL COMPUT ING MACHI NE o mled Dec. 16 1920 8 Sheets-Sheet awpwwtow j/aarzjm ,jmar'y 35 mm gm m Jam; (flax/2211a):

BEST AVAiLABLE COP NOV. V M. SAMBURG ET AL COMPUTIN MACHINE a Sheet s -Sheet s O i Filed Dec. 16, 1920 aky are tum avwemiio *v as Ana nm:.- :m

Q. mm

BEST AVAILABLE COP Nov. 30 1926. 7

- M. SAMBURG ET AL COMPUTI NG MACHINE 8 Sheet's-Sheet 4 Original Filed D60 6. 1920 Jfllaarz'm Jkmbzzr r a imm- C. Ear/Maria: 3&13 M11211, 6

Nov. 30 1926.

BEST AVAiLABLE COP M. SAMBURG ET AL COMPUTING MACHINE 0 Filed Dec. 16, 1920 z6rlgln1%}2 a shee tssh e et 5 gmoautom BEST AVA'LABLE COP.

Nov. 30,1926. 1,609,206

M. SAMBLJRG ET AL COMPUTING MACHINE O i Filed Dec. 16, 1920 8 Sheets-sh t 6 l V31 35 awumtou Julia! (5 fol/imam @51 Mei? Mom tug BEST AVAILABLE COP Nov. 30 1926.

COMPUTING MACHINE M. SAMBURG ET AL awve/ntozm 111M122? Jk/IzizZ/y (1170a? man? 8 Sheets-Sheet s 3513 11 WWW Patented Nov. 30, 1925.

BEST AVAILABLE cop MAURICE SAMBURG AND James; 0. rrlo c ii rau, orupw YORK, u.

COMPUTING Application filed December 16, 1920, Serial No. 431.154. Renewed February 12, 1928.

Our present invention relates to computing machines and more particularly to machines for performing the operation of addition and preferably also that of subtraction.

An object of the invention is to provide a mechanism of the above type which shall he compact, light and simple in' construction, yet reliable in action under hard usage.

' Another object is to provide a'co'mputmg mechanism of the type referred to, of such construction that it can be readily associated with a common form of printing mechanism, such, as for instance, an ordinary typewriter to cause the latter to print the numbers concurrently with the actuation of the computing mechanism, and certain features of the-invention reside in a novel combination of our computing mechanism with such typewriter or other printing mechanism.

Another object is to provide a computing and printing machine of flexible character to suit various kinds of work and which shall not require special forms, and which shall more particularly be susceptible of performing all'or'any combination of the following functions: making vertical or cross additions, 'printing'anywhere on the sheet, adding dol1ars,"we i hts, quantities or any other uni-ts, punctuating the numbers as desired andmaking in one operation any number of carbon copies, including the sums figured.

Another object is to provide a computing mechanism wh ch'when associated with anyordinary typewriter will not impose on the latter any strain'or force greater than those imparted to it in ordinary operations for correspondingpurposcs and will still allow said typewriter to be operated at all times without actuating any part of the computing machine and through all functions, "identi why as though the computing mechanism were not attached thereto."

Another-object is to provide a computing mechanism which can be attached to all typewriters as present made free from mechanical connection with any operating part thereof, andw'lii ch will bein'operative position relative to the typewriter keyhars, even though the spacing ot the key-bars on the several typewriter makes may vary considerably.

Another object is to provide accurate computing mechanism susceptible of cooperation with a typewriter to cause the lat ter to correctly print concurrently with the actuation of the former; and this although the'keystroke of the typewriter isappreciably greater or less than that of the com-- putingmechanism.

Another object is to provide a computing mechanism which when attached to a typewriter will allow'the typewriter to be used on the ordinary drophead--type of desk without interfering with the closing thereof, and'which will not necessitate chopping into the desk in any way in order to obtain this result.

In a preferred embodiment for carrying outthe above objects, we provide a complete self-contained computing 'machj-ne'of dimensions' and arrangement such that .it can readily be mounted on the frame of many of the common makes of typewriters, above and free from interference with the 'normal operation of the typewriter keyboard, the above mentioned printing by the typewriter concurrently with the 1 arithmetical operation by the computing'mechanismbeing effected-by a disposition of keys 'or other actuating members of the latter, at such inter?- vals that'when the device is mounted upon the typewriter, the number key members of the latter are in the path of operation of the former. The typewriter platen can, therefore, be shifted at'will in the courseof addition, either laterally or circumferentially to suit the particular form being used and the typewriter keyboard may be operate-zl'to print any characters without interference with the accuracy of the arithmetical operation performed by actuation of thc computing attachment.

Our computing attachment although preferably employed in the relation above set forth may be used to adyantage apart from a' typewriter in which event the results of computation are'readable but neither the numbers nor the sums are printed.

'The"present'applieation is directed to an improvement on that of our copending'applica tion' Serial Np.' 344, 289 filed December BEST AVAILABLE cop.

1.1. 1919. in which the foregoing objects are Fig. 6 is a sectional view taken along the also accomplished. As to all common subline 66 of Fig. 2,

ject matter, this application is acontinuation F1g, 1s a sectional v ew taken along the thereof.

The mechanism in the preferred embodiment is so constructed that it will operate vith unfailing accuracy whether used as a typewriter attachment or as a separate machine. For this purpose the preferred mechanism provided lth improved means for preventing overthrow by inertia after each operation of the totalizer, for preventing quick repeated ope: ion of a key before return thereof to home position, for preventing a reverse operation of the totalizer dur ing the return of the operative parts to home position after each operation. for insuring shifting of the totalizer thrcmgh the width of one and only one number wheel after each kev depression, for compelling depression e! a key wl'ien once commenced to' be continued to the end of the stroke thereof, for preventing depression of all other keys when any key is wholly or partway depressed, and other safeguarding means referred to hereinafter.

According to another preferred feature, the adding mechanism is provided with means functioning to avoid double actuation by inertiaof a typewriter number key-lever and consequent printing of a double digit for any single operation of the adding machine attachment. in auxiliary load is employed for this purpose to resistoperation more particularly of the keys of lower number value. In the preferred embodiment a differential loading means employed to produce equal resistance on all keys. this resistance being equal at all times to the greatest resistance met in normal actuation of the most fully loaded key, namely the numher 9.

Air-cording to another feature. the adding mechanism is reversible in clmracter, and reversing gear means is provided. readily accessible from the exterior to set the mechanism for direct subtract-ion.

Other objects and features will appear hereinafter.

Referring now to the drz'iwings, in which is shown a. referred embodimentof the several features of our invention.

Fig. 1 is a front elevation of the type writer with our mecaanism applied thereto,

Fig. 2 a top view thereof.

Fig. 3 is a sectional view taken along the line of F g. 1.

Fig at is a detail view of an adding key.

is an elevation. of our adding machine attachment. the cover of the mechanisln being shown in section to reveal the interior pint...

5 is a de-ai along the line f line 7-7 of Fig. 6,

Figs. 8, 9, 10 and 11 are respectively sectional views on an enlarged scale taken along the

lines r9

8, 99, 1 10 and 1111 of Fig. 5,

Fig. 12 is an enlarged plan view of the subtraction mechanism and related parts,

Figs. 13 and 14 are sectional views taken along the lines 1313 and 1 l-1l of Fig. 12,

Fig. 15 is an enlarged side elevation showing the carrying idlers and totalizer idler gears,

Figs. 16 and 17 are sectional views taken along the lines 1($16 and 17-47 of Fig. 15,

Fig. 18 is a plan of the control plate, Fig. 19 is an end view of the control plate,

Fig. 20 is a plan of the operating late,

Fig. 21 is an' end view of the operating plate; and,

Fig. 22 is a sectional view taken along the line 2222 of Fig. 6.

Similar reference characters refer to similar parts throughout the several views of the drawings.

The typewriter and the relation of the addz'ng attachment therewith.

Referring to Figs. 1 and 2, we have shown in general outline a typewriter comprising a frame 1, a platen 2, a keyboard 3 comprising the usual letters, numbers and punctuation keys, and a set of key levers 4-, one connected to each key and extending rearwardly therefrom and arranged in any known manner for printing the corresponding character upon a. sheet on the platen when a key is depressed. The machine includes the usual escapement not shown for advancing the platen after each key depression.

The general arrangement of parts described is common to the product of the various large typewriter manufacturers, such as the :Underwood, the Remington, the Royal, the L. C; Smith and OthGl'S. Most of the above makes of machines and others are equipped with a name plate 5 secured to the frame 1. Our computing machine is so designed as to be universally applicable with little trouble preferably to the frame 1 of each of-the types referred to, serving as a. computing attachment to form a combined typewriter and computing machine. on. computing mechanism is, however, complete in itself andmay be employed to advantage apart from any typewriter or ofher printing n'iechanism, as will appear more fully below.

The computing mechanism is shown in general outline in Fig. l and has a base plate 6 and a casing 7 in which is enclosed the computing mechanism. The casing has openings 8 through which may be read nunrhers on the .totaliiei wheels. registering the results of the various arithmetical operations lghe ma'chi'ne is provided with a set of number keys 9, one corresponding to each digit as shown, and a zero key, which may be designated asconruting or adding keys to distinguish from t e typewriter number keys. Eaeh adding -key ;has associated therewith. a key bar 10 sl idable in a corresponding groove 11 in the base plate 6, each key bgir extending directly over the key lever shank {of the corresponding number key on thetypewriter asappears best in Figs. 3 and5, so that depression of any of the computin'g': machiriekys will operatethe computing nechanisnran'd concurrently therewith will cause depression .of the corredin numbei key on the typewriter and can s'efthe digit to be printed, upon the platen. The width .o. f eachkey bar extends transshi-eih le 9 t e. wi p typewriter. key I leye'r so that the above acaoirwillgtak'e place with'oiitneed for special c6" ;or. aligning means of any sort. 'i 'e.stridingkeys are preferably mounted at tEe-i mard end of brackets 12 secured to. e ckeyba'rs immediately below the bottom 9} casing 7 the adding keys being raised as sh qwn, in order to provide ample knuckle clearance when operating the top row of typewriter keys, The forward face 13 of the casing slopes downwardly toward the [plate 6. to allow knuckleciearance for operatiouof the keys 9. A front plate 17 extends across the width of base plate G an d oyerlaps the lower ends of the key bars, the upperedge of the front plate limiting he depression of the adding key when reached by the key bracket 12.

In the-various common makes of modern typewriting machines above enumerated and in others, the keyboard is arranged as shown in Fig. 2, .the number keys 2 to 9 and zero being located in the fourth or rear row and Zia L key, in the second row serving for printingthe digit 1. The key bars of the computing, mechanism are so disposed and of such relatively large width as to allow for ua considerable variation in the spacing of the typewriter key levers. As at present made thediiference in the distance between t he number 2 and the number 0 keys is 1-1;", yet our adding key bars will coact with these typewriter .keys, when attached to either the Wide or ,rrarrow machines.

1B; .reason,of the fact that typewriters are. d si;ziit 1.or equal strokeof the keys and the 'L. key -h as a longer, 'levlerarm. than the niiiiib'er keys in the rear row, the'portionot tlieLkeyllei er arni'vinthefplane of the addkey. bars will iiiove th1fo i1gh a smaller i cir a-iull k ey depression than will the corresponding, portion pt the. other key Tlie'ky bar for the n'iiiiibei ene k is accordingly made correspondingly shorter BEST AVAlLABLE COP as; shown at 1% (Fig. 5) so that, when the. ninnher one adding key is depressed the corresponding typewriter key lever will move through the lesser range reqilired.

In Fig. 1 the computing machine is ends of the ears register with the regulanon holes in the name plate of the Royal t \51')e\\;'rite r so that

screws

15 and 16 may readily be inserted through the car's to'c'oncurrently secure to the frame, the name plate and computing niach'ine attachment with the key bars directly over the shanks of thecorresponding typewriter key levers, as above noted.

The holes for screws 20 and- 21 of the computing machine correspond in position with the screws for securing the name plate in place in the Underwood typewriter, so that our computing machine may be attached to the Underwood machine by dispensing with the ear-s18 and 19 and putting screws of appropriate length through the holes provided in the front plate 17 and in the name plate of the typewriter, and into the typewriter frame. In the Remington typewriter, there are no screws accessible from the front of the machine, and the computing machine is preferably secured in place by ears having appropriate clamp screws (not shown) coacting with the sides of the frame. The L.

C. Smith having its name plate secured to its frame by screws in a still different position, it would only be necessary to provide ears to suit. So by providing a suitable front plate construction as by changing the ears to suit each typewriter, the. adding attachment can be easily conneetedto fit any machine.

It will be seen that the computing machine Can be installed as an attachment for Reming ton, Underwood. Royal L. C. Smith or i other typewriters by any unskilled person and in a fraction of a minute. In most cases it is necessary merely to remove a couple of screws from the typewriter. to place the back plate of the computing machine against the typewriter name plate. screwingthe same in position by use of apair of screws of slightly greater length substituted forthe removed screws, and using the same tapped holes in the typewriter {t me There is no adjusting or ali ning necessary, since the ears bring l-ieys into exact position for proper operation or; sci. machine.

It w.i 1l.he urd stood that. are ems chine will, therefore, be referred to hereafter ton machine for instance the adding key,

as an adding machine and the number keys thereof as adding keys.

The lengths of key stroke for the different makes of typewriters differ. In the Remingthe part of the key lever shank in the path of the adding machine key bars has a stroke of 20/32 inch, in the Underwood 18/32 inch, in the Royal 16/32 inch and in other makes, the stroke is within these maximum and minimum limits. The

key stroke of our adding machine regardless to which make of typewriter it is to be applied is preferably 19/32 inch and when the attachment is applied to any machine in the manner above described the apparatus will operate satisfactorily in every case.

In the case of the Remington machine, the key bars with-the exception of the number 1 key will rest directly on the tops of the corresponding typewriter key lever shanks in the manner diagrammatically shown in Fig. 5. The final 1/32 inch of the typewriter key stroke, the difference between the 20/ 32 inch stroke of the typewriter and the 19/32 of is traversed by reason of the ineitia orfmomentum imparted to the key lever in the above operation.

In the case of the Underwood machine, the

bottom of the adding key bar will be 1/32 of an inch above the shank of the typewriter lie and, therefore, the attachment key after taking up the short lost motion will push the typewriter key lever through its full stroke.

Features of the adding machine construction.

Referring to the drawings, the key bars in the grooves 11 in'the base plate terminate at their upper ends each in a forwardly extending short tongue 22. The casing 7 has

end walls

23 and 24 between which extends preferably an operating plate 25 shown by itself in Figs. and 21. The operating plate is provided with a series of rearwardly extending struck-up lugs 26 in stepped relaion, as shown, one corresponding to each key, each said struck-up lug being in the path of the tip of tongue 22 on the corresprmding key as best shown in Fig. 8. It will be seen that as an adding key is depressed. the key on:- moves free of the operating plate until its tongue comes into conwith the --:r=res=: ionding sa'uck-up lug and during the remainder of the key bar movement, the operating plate will travel therewith. The lugs are stepped in such relation that. the amount of displacement of the operating plate will be directly proportional to the number value of the key. Thus, the struck-up lug 26 (see Fig. 20) corre sponds to the number 9 key and the lug 26" BEST AVAILABLE com to the number 2 key, the intermediate lugs corresponding in succession to the number keys of intermediate value. The lug 26' to the right of the lug 26 corresponds to the number 1 key. There is no lug at the zero position, consequently for zero actuation the operating plate does not move.

The operating plate has preferably short ledges 27 bent up from the opposite ends thereof, gear teeth 28 being formed on said ledges to form a rack, tongues 29 left continuous with the main length of the bar at the ends of the rack being arranged to slide in corresponding grooves 30 in the

end plates

23 and 24. The racks are permanently in mesh with

pinions

31 and 32 near the ends of an operating shaft 33 journaled in the

end walls

23 and 2 1. Encircling the operating shaftis a coil torsion spring 34: secured thereto at one end as at 35 and secured at the other end to a fixed point asshown at 36 in ig. 11. As the operating plate is actuated by depression of any adding key, the rack and pinion connections at the opposite ends will prevent any tilting or binding and the operating plate will move downwardly with a pure movement of translation, rotating the operating shaft and storing energy in the torsion spring 3 1 which energy will be released to return the operating plate to its upper or home position after the pressure upon the adding key is released.

The impulse from the operating plate through the operating shaft is transmitted to the totalizer, designated in its entirety by letter T, through a master wheel 37 arranged to rotate with a sleeve 39 upon the operating shaft during the operating movement but held against rotation during the return movement thereof to avoid reverse movement of the totalizer. For this purpose, the master wheel is rigidly secured preferably by a screw 38 upon the sleeve 39 which encircles and is free to revolve around the operating shaft and extends toward the left from the master wheel, being held by any desired means against sliding movement along the shaft. A driving connection between the operating shaft and the sleeve is established through a one-way (latch preferalt-ly a ratchet clutch 10 near the left end of the operating shaft. The clutch iin'ludes a driving clutch member 41 pinned to the shaft and a driven clutch member 4-2 carrying gear teeth 13 meshing with a gear is: idly revolving upon a fixed shaft parallel to the operating shaft, the latter gear having: formed rigid therewith a second gear 46 which meshes with a master wheel driving gear 47 formed rigidly upon the end of sleeve 39 opposite the master wheel. A compression spring 43 is inter posed between gear 47 and clutch member 12 to maintain the clutch operatively connested.

As a result of the above construction, it will be seen that as eneddingl-keyis-'depressed, the operating plate -25 -will move downwardly, driving'the operating shaft 33 through the .rack and

pinion connections

31 and 32 and storing'energyin .torsion spring 34, the torque"bing transmitted to the inaster wheel 37 through the teeth of clutch menber 42, clutch gear 43,- countershaft gearset and 46 to the master wheel driving gear 47 and through sleeve 39 to the master wheel 37. The master wheel is thus'rotated through-an jingle proportional to the number value of the"depresscddq'ey and wi-ll advane 't 1c totalizerto'a corresponding extent. vlVhen the pressure o fthe finger is removed from the adding key, the torsion spring-342' will expand; rotating'the' operating shaft and with it the pinions'31,'32' thereby returning the operating plate' 'to home position:- ;The clutch 40, however, will" open, the :driven clutch member being pressed 'outofvengagem'ent "with" the "driving clutch in'e'mber against the coinpression of spring 48 so that the"-master wheel "will not"- be driven: in 'reversedirection." i

an r. Tabulqting or decimal system and escape- The 'totali zer to be described more fully belo'w compris'es a set of nuinber wheels 50, upon 'sha'ft 5'1,ahd arset of totaliz'er drivingidler 'gears'52 upon 'a second shaft-53, as best shown in 17, said 'sets *of number wheels and gears'beingfbothisupported in'a carriage- '54 having an operating thnmb piece projecting through at slot 62 in the top of casing," 7 the other end of the thumb -lpiece which is-in sid'e the casing having a'n extension serving as a' stop for settingthe totali'zer in the correcttabul'ar position for the" number to be adcled. Tabnlating keys 56 properly T spaced apart are' provided prefer ably in a support 5? on the-upper surface of corresponding-"to each :tlecima-l place within the rhn'ge oi themachine and'bearing a' -corbe set for "the addition of 'any number of 'the' order ot' the "depressed tabnlator' key. The key of highest order; in the specific embodi1nent,'the M or million key is-preferably i1 d'um'niy,'the tliunib piece beingliin'ited'by theend'fiil ofslot 62 to set "it to positionior a nnmbcr of digits.

"A' compressionspringt i dipsoscd to- BEST AVAILABLE COP\ ward the right of the carriage 54 and encircles the shaft 5l,=urging the carriagetowa rd the left; a pawl-andescaper'nent ratchet rat-lg mechanisinnow "to be-desc ribed, retaining the carriage against-the-pr'essure of thesprihg; fille pawl: and ratchet mechanism is preferablyarranged to betripped at the lowest po-int o-f depression ofneach key to allow the springto push the can rizige forwardly through the-width of one number wheel; preparatory to the adding of, the following'digit; :Eorthis purpose, we preferably pivot a ratchet rack barfit-as at 65 upon .,the right-hand end of the carriage. The bar is provided with a lower set or ratchet teeth 66 'each -lmin e te -ct cal edge "67 andihn 'iin'clined dge "68. T he clista nce between successiveteeth is 'equtil' '-'to the width *of 'ti' miniberfwheel'. 'At' 'its' upper edge the 'ba'r has"'2i second set of'teeth 69 boththe. edges-pf 'whi'h are inclinedhs shown. 1 A yerti'cl barf YO' is rigidly seciired eiigagement 'witli "said pawl"-{todth"- its shown, against the texpixn'sionwt spring 63.

ratchet The awl h'n'drzitchet mechanism ratchtbar ne'er" it's ftee end" to ra'i'se'theping ot the riitcht'fitlie coilf spring"63 in its expansi on will inove' 'the'ed riitr e -t'oward the succeedihg upper ratchettbotheng aging the upper p wl-'74, which'lizittr'iirgesjtlie r'zttchet bar downwardly assisted bjf contractiomof cqil 'spring'73-"to pryent shifting through more tlitin onetooth' an tin'IeZfSinde the form 'offlth teeth and theldistance between stationary paw'ls 72' and 74 isjnst' enough to allow escapernent' ratchet rack 64 'to" mote between them only when'in' conta'ct with eitherone' or the other-"of theml 'it isbirident that ratchet rack 65 is' positively controlled at all times. This control would'of itself p'ret ent the carriage-shifting more than one'tooth at- 1V- tiiiim indp'ehdentot coil spring-'73. Spring-"73, however; does 'serre"to speed tip the drop'of rack 64s in a'dditi'ontoitssateguarding 'efi'ects. ""Thei"'le\ er"75 ispreferably tripped by a controlplate parallel to'end adj aeent; the

bn se plate 6 andiinterposed"between the key bars 10 and 'the' operating'plate "The tongues 22 tt'heends of the key bars preferably overla and rest on the upper edge of the control p ate as best shown at 81 in Fig. 9, the tips of said tongues as heretofore noted, coming into contact in the course of their downward movement with the corresponding struck-up lugs 26 in the operating late. As shown, the tripping lever has a tail 82 in the path of the lower edge 83 of the control plate, so that at the end of the depression of each adding key, the control plate causes the tripping heretofore noted.

The key loading means.

When our adding machine is used in combination with a typewriter in the manner above described and in the absence of special provision, a difficulty might be encountered in the printing, more particularly, of thenumbers of lower value. As the operatorin practice presses the adding keys with equal force, the adding keys of lower number value at the start of the stroke would move considerably faster than the number 9 key, because of the material range of substantially free travel of the former prior to effective engagement with the load actuating operating plate, and then would slow up at the latter part of the stroke when engaged with said loaded operating plate. The typewriter key-levers associated with adding keys of lower number value, due to the initial high speed of actuation and the sudden addition of resistance with consequent reduction of speed of depression, would thus acquire considerable momentum, and might move downwardly in advance of the adding key to print the number, actuate the typewriter'escapement to advance the carriage, and be engaged the second time by the adding key bar in its continued downward path to print the number a second time. Also in the case of the number 1 key, the impact of the adding machine key on the typewriter key due to the acceleration gained by the former in its lost motion before touching the typewriter number 1 key shank would provide an additional tendency toward double printing. Thus, it is possible, more particularly, that the number 1 addin; key, while accurately operating the totalizer might cause the printing of 11 instead of 1.

To obviate this difiiculty we prefer to provide differential loading means to resistthe advance more particularly of the adding keys of lower number value, so that excessive momentum shall not be acquired by the corresponding typewriter key-levers and this, without adding to the force required to operate the highest or number 9 key.

In the preferred embodiment, this loading means is arranged to resist the movement of each adding key during the portion of its 517 floating upon the operating sleeve 39 which meshes in turn with a pinion 8S pinned to a loading shaft 89 extending the entire width of the casing 7 and journaled as at 90 and 91 in the

opposite end walls

23 and 24 thereof. The rack 86 on the control plate meshes in similar manner with a, floatgear upon the operating shaft which in turn meshes with pinion 93 near the rightcnd of the loading shaft. Encircling the right-hand portion of the loading shaft is a torsion coil sprin 9a: pinned thereto at one end as at an secured at the other end to a gear 96 floatingly mounted upon said loading shaft and adjacent pinion 93. The gear 96 meshes with a. gear 97 fixed upon the operating shaft.

As a. result of the above construction, it will be seen that as an adding key is depressed, the advance 0; the corresponding key bar will cause a downward movement of the control plate, which through its

racks

85 and 86 will rotate

gears

87 and 92 re spectively, the

gears

87 and 92 in turn rotating the

pinions

88 and 93 on the loading shaft, one function of which is to cause the control plate to move without binding or tilting, that is, in parallel translation. Throughout this action, the floating gear 9-3 upon the loading shaft is held against rotation by gear 97 upon the operating shaft, since the operating shaft is prevented from rotating by the pull of its coiled spring 34. As a consequence the end 95 of the loadin spring rotates with the loading shaft, but the end which is secured to the floating gear 96 is retained against rotation, so that the loading spring will wind up as the adding ke is depressed. thus offering sufficient opposition to the depression of the key to pirvent gathering of excessive inertia by the typewriter key lever under control thereof. and storing additional energy to return the control plate to its upper position when the key is released at the end of its stroke. soon, however, as the tongue on the end of the key bar comes into engagement with tincorresponding struck-up portion 26 on the operating plate. and the latter begins to be depressed thereby, and through the racks 28 rotates the

pinions

31 and 32 on the operating shaft, the gear 97 on the operating shaft will rotate the floating gear 96 upon to ofier an opposition approximately equal to that encountered in the actuation of the mechanism for operating. the totalizer. Thus, each key is opposed b-y'an auxiliary load during the portion of its stroke prior to engagement with the operating plate. Since the; tongue 22 on the number 9 key in the preferredembodiment is at the beginning of it's stroke in direct engagement with the corresponding key on' the operating plate, the

loading mechanism does not come into action for this key, and enters into operation in the caseof each of. the other keys for an interval varying in an inverse ratio with the number value of the key, so that the total resistance encountered in the actuation of each key shall be equal to-that for the number 9 key.

In other words, the loading spring turnishes a variable or differential method of adding a resisting load to the otherwise comparatively free portions of the stroke of the keys of number value less than 9, and this added load will at all timesbe just enough to make the total key resistance for any key equal to the force of operating the number Qkey. Thus, it is seen that the key resistance on all numbers can be made-the same.

A further function of the loading means appears in the next to the last paragraph under heading The master wheel controls.

The master wheel controls.

To prevent undue advance of the master wheel by inertia and for other purposes which will appear below, we provide a master wheel governing stop, preferably in the formof a pawl pivoted as at 101 to the frame bar 71 and extending in a plane at right angles to that of the master wheel and having a pointed tooth 103 arranged to enter between teeth of the master wheel. A. stop control bar 104 formed preferably of sheet metal has a bent end (see Fig. 22) extending transversely through an opening 105 in the tail 106 of the stop member and provides a shoulder 107 extending transversely between the stop member and the backplate. The upper end of the control bar has a forwardly extending tongue 108 fitting into a notch 109 in the upper edge of the operating plate.

In operation, as an adding key is de- BEST AVAILABLE COP pressed, the master wheel is caused to rotate the manner heretofore described and at the end of the downward movement of the control plate, the tongue 110 at the lower edge of the latter contacts and depresses the shoulder 107 upon the stop control bar, causing a movement of the stop element about its pivot and an entry of the pointed tooth 103 between teeth of the master wheel, until at the extreme end of the operating movement, the tooth 103 will be fully meshed between teeth of the master wheel and will prevent further movement thereol either forwardly or backwardly. A friction spring lock 111 uponthe frame bar 71 adapted to fall into either of two depressions 111 at the back end of stop 100 serves for frictionally locking the stop pawl in either of its two extreme positions, to insure against chance movement of the stop pawl while the control plate is in anyintermediate point. of its stroke.

When the operator releases the adding key. the coil springs 3st and 94 snap the parts back. as heretofore described. During this return movement. the pawl tooth remains in engagement with the master wheel, locking the same against any shifting movement until the operating plate is near the extreme end of its return movement. whereupon the bottom of the notch ,109 therein comes into contact with the tongue 108 on the control bar and raises the tail of the stop pawl, moving the latter against the resistance of the spring lock 111 out of engagement with the master wheel, leaving the latter free for advance in response to a succeeding adding key operation. It will thus be seen that the locking of the master wheel takes place concurrently with the end of the down stroke of the control plat-e andthat the master wheel is maintained in locked position until the extreme end of the return stroke of the operating plate. By this construction, it will be seen that should the adding key be given asecond downward impulse by the operator. in the course of its return stroke. such impulse would not aiiect the totalizer in any way since the governing stop locks the master wheel against displacement until the end of the return stroke.

It will be apparent that the loading shaft and the spring 34 above described will prevent depression of the operating plate at a. high rate of speed which might occur in their absence, particularly, for operation of adding keys of the lower number values. ihus, is eliminated'the likelihood of acceleration of the operating plate in advance of the adding key, and the consequent excess advance of the master wheel 37.

A pawl roller 112 upon the end of a pivot arm 113 coacts with the master wheel, being -held in engagement therewith by a coil spring ll l, one end of which is secured'to as the master wheel governor stop is out of engagement therewith.

The zero operation.

" left stationary for zero key operation. The

operating plate being relied upon in the case of the digit keys to return the master wheel locking stop to inoperative position, the end of any such stroke finds the locking stop control bar resting on top of the operating plate. Therefore, for zero operation thelocking stop cannot be operated by the control plate at the very end of the control plates normal full stroke, since any movement of the locking stop would move its control bar downward, and this in turn would pull down the operating plate upon which it rests. It is plain that such actuation of the operating plate for zero operation would result in numerical actuation of the totalizer and so produce an error in the calculation. For this reason, the control plate is so designed as to cause operation of both the escapement mechanism and the master wheel lock for the various digit keys, as above set forth, and to cause operation of the escapement mechanism but not of the master wheel lock for the zero operation in the manner now to be described.

Pivoted upon the control plate as at is an L-shaped lever having a horizontal arm 116 and a vertical arm 117 the upper end of which overlaps a notch 118 in the upper edge of the plate, said upper end being in the path of the finger 22 on the zero key bar 10. A wire spring 119 presses against the free end 120 of the horizontal arm and urges the upper end 121 of the lever upwardly, this upward movement being limited by a stop 119 formed integral with the control plate. A lug 122 at the lower end of the lev r and adjacent the rack bar 86 is in the path of aportion 123 on the ratchet oper ating or tripping lever 75. Upon depres s on of the zero key, it will thus be seen that :r the first small fraction of an inch, the lever 11G-117 will be moved about its pivot against the resistance of the wire spring 119 vitl'iout moving the control plate, the tongue 22 of the zero key entering the notch 118, and thereafter moving the control plate. he control plate, therefore, moves downwardly under the influence of the zero operating key through a range smaller than for the other keys by the depth of notch 118 so BEST AVAILABLE COP\ that the tongue 110 at the lower edge thereof will not reach the shoulder 10'? of the control bar for the master wheel stop and the master wheel stop will not be actuated. The lug 122 on the lever 1l6117 however, moving a distance equal to the full normal range of the control plate, will come into engagement with the tripping lever 75 and will, therefore, cause an advance of the totalizer carriage as for any other adding key.

The full stroke mechanism.

This mechanism is for the purpose of insuring that when any key is operated, it will be depressed to its full extent and 0perates by preventing the return of any such key until it has been depressed its full stroke. For this purpose each of the key bars is provided with ratchet teeth 125 near its upper portion and the sharp edge 126 of a pawl plate 127 is urged by means of a wire spring 128 into coaction with the teeth of the key bars as will appear in Fig. 8, the pawl plate extending substantially the width of the casing. The pawl plate is preferably pivoted to the side walls of the casing by screws 129 extending through integral ears 130. A full stroke control piece 131 for cooperation with the pawl plate extends substantially the heightof the casing 7 and has a tongue 132 overlapping the upper edge of the control plate and an off-set pointed tongue 13-3 slidable along the base plate and under the edge of the pawl plate and adapted to lift the pawl plate out of engagement with the key bar ratchet teeth at the very bottom of the key stroke. The full stroke control piece has a shoulder 13 1 between the pointed end and the main length thereof arranged in the path of the control plate. It will be seen that immediately upon the depression of any key, the toothed edge of the pawl plate will come into mesh between teeth of the key bar, and return of the key bar and of the enacting mechanism will not be permitted. lVhen the key is depressed to the extreme end of its downward stroke, the lower edge of the control plate movable therewith comes into engagement. with the shoulder 13 1 upon the full stroke control piece and moves the latter downwardly into engagement with the pawl plate, forcing the latter out of mesh with the ratchet on the key bar, so that upon release of the finger piece, the key bar may be returned to home position. At the very end of this return movement, the upper edge of the control plate comes into engagement with the tongue 182 on the upper end of tl e control bar and returns the latter to the home position shown in Fig. 5; thereby dropping the pawl plate into contact with the key bars again.

By preference a pair of the full stroke pieces which act simultaneously as above de scribed, are provided, the two members being best shown in Fig. 6 and indicated by

reference characters

131 and 131 one-near each end of the casing.

T he two-lacy mechanism.

To prevent operation of more than one key atatime, we provide a system of ,stops to lock the remaining key bars against depres- .sion when any one key isu'hoily or partly depressed. For this purpose we prefer to pivot .to the base plate, a plurality of inyerted generally T-shaped stop members 135. the cross-bar 136 of each stop member extending preferably from midway between the sides of the key bar .on one side thereof -tp:midway between the sides of the key bar on the other side thereof and in contact with-said key-bars, the cross-bars of the successive stop members being. preferably in contact with each other as shown at 137. By preference the ends of the stop members are. curved, .as shownat 138 and the key bars are .of smaller-thickness below than above the 4 crcssmember, each key bar having a curved shoulder 139 preferably in direct contact -wit-h the upper edges of the adjoining stop -members. Upon-depression of any key bar. the curved shoulder 139 thereon will push the stop niembers 135 at the opposite sides .thereof out of,its. path, and until the key is returned toliome position, none of the stop members can be shifted toward said key. so that there will bsan obstruction in the path ofevei'y other key, thereby locking the v.remaining keysz against displacement.

Thezero and number 1 keys are so close togetherthat -there. would not be room enough. to place a stop member between them as in the case of the remaining keys. For

140 thisareason, the stop member carrier 1-10 is pi\-'.oted tothe front plate in central position between thekeys and lodged ina depression kill-therein which depression is also made to .limit ,the movement of the stop member carrier outwardly. A rivet head 142 on the free end of thestopniember carrier is in the {path of the curved shoulders 138 on the zero and munberlkeys, but does not swing completely under these keys at any time. thus allowing for easy unlocking upon operation of these keys.

The total 55 -'lhetotalizer mechanism has-many feaand particularly in Fi l riage 54, and the set of totalizer driving idler .with. .star wheel 159 in the plane of the. notched BEST AVAILABLE COP: 9

gears 52 loosely revolvable around the sleeve 156 which slides freely on shaft 53 and is also held rigidly in the side of carriage 54 is, asheretofore-noted, shiftable by thetabulatormechanism to the position correspondingto the number of digits in the number to he added. it can be seen that the construction of short tubes rigidly-held in the sides of the sliding carriage provides a very. stiff mechanism independent of the comparative- -ly long and slender shafts and acts to prevent springing of the latter.

Each number wheel has a ten toothgear 1 31 upon its right face and at its left :1 Geneva loc c'ng disk 152 formed integrally with a hub 153 having a single tooth 154 aligned with the notch 155 in the locking (list: 152. The totalizer driving idler set comprises a sleeve 156 on shaft Upon the sleeve are. mounted a set of identical members A and a set ofidentical members B alternating with each other. :Each member A comprises a gear 157 meshing with number wheel gear 151 and a hub S integral therc- Each member B comprises a Geneva Geneva locking disk 152 of the associated number wheel. and a gear 160 integral therewith in the plane of the associated single tooth 154. The successive members A and B are in contact. with each other. as shown.

Upon sleeve 39carrying the master wheel 37 is mounted asuccession of carrying idlers 161. Each said idler has teeth meshing at all times with gear 157 on the adjacent member A of the totalizer idlers and with the contiguous gear 160 on member B. In the specific embodiment, the carrying idlers and thetotalizer driving idlers are each provided. with nine teeth, but it will be understood that they may have any other. number of teeth.

Assuming that the carriage has been shifted to the position shown in Figs. 15, 16 and 17 for addition of a number ofthree digits. the master. wheel 37 now meshes with the. totalizer driving idler gear 157 on the sleeve 156 (Fig. 15) and this gear in turn meshes with gear 151- integral with the number wheel in Fig. 17. As the adding key is depressed the master Wheel rotates and will rotate the number wheel gear 151 through gear 157 advancing the number wheel to add the digit correspondingto the adding key depressed. As the number 9 on the numberwheel 151 is reached. the single tooth 1 4 comes into engagement between teeth of the correspondingtotalizer. carrying id-lergear 160 of-niember B and the vsaid idler gear is. thereby. rotated through the width of one tooth. The carrying idler 161 meshing with gear 160 rotates through one tooth and since-it also meshes with gear 1.57, the latter is rotated through one tooth, and consequently advances gear 151% on numher wheel through one tooth, thus per- -forming the carrying operation.

Excessive or overthrowing movement is prevented during this carrying operation, as the Geneva star wheel 15$) which was unlocked by the presentation of the unlocking notch in Geneva disk 152 simultaneously with the presentation of the single carrying tooth 154 will now act to bind against the periphery of the disk 152 as soon as the tooth 154 has performed its advance. The carrying action proceeds in similar manner for each of the decimal places.

The teeth of the carrying idlers are beveled at their opposite sides as shown at 162 and 163 to expedite the shifting of the sets of

gears

157 and 160 which mesh there with, both in setting the carriage into tabu lating position and in the step by step automatic return movement. The carrying idler units which are in mesh with gears on the car iage are as will be apparent always kept in alignment. Those carrying idlers at any time to the left of the carriage are kept in proper alignment for ready entry into mesh by means of a bar 164 riveted as at 165 to the carriage frame and extending between two teeth of the idler gears to the left of the carriage, Thus, the carrying idlers will readily enter into mesh with the totalizer idlers as the carriage moves toward the left after each key depression. A small rod 166 extends from the stationary shaft and has a free left end 167 substantially in the plane of the outer surface of the master wheel for the purpose of keeping in alignment those gears of the totalizer idler group which may at any inst-ant be to the right of the carrying idler set as shown in Fig. 15.

As the carrying idler gear 161 in immediate contact with the master wheel 37 tends to be carried along by friction in view of the fact that. the master wheel is rotated for every depression of a digit key. a pawl 163 similar to pawl 112 heretofore described but liu'eferably somewhat. wider to correspond to the width of the gear is normally urged between two of the teeth thereof, thereby preventing undesired movement.

Each element of the totalizer and the totalizer as a whole, it will be seen has a type of symmetry such that it may be operated forwardly or backwardly with equal facility.

Reversing mechanism.

In view of the symmetry of the totalizer, it is merely necessary to reverse the gearing by which the same is driven in order to render possible the performance of the operation of subtraction when desired. For performing the shifting function a reversing gear 170 (see Figs. 5, 12, and 13) is preferably employed, this gear being mounted upon a stub shaft 171 fixed in end plate 23,

and being constantly in mesh with the driving gear 47 on the operating sleeve but out of mesh with countersha-ft gears 44 and 46. A reversing button 172 slidable upon shaft 51 preferably projects from the left end of the casing integral'with a bushing 173 fitted into a. corresponding hole 174 in said end and rigidly retained with respect to the shaft by means of a spring locking ring 175 adapted to drop into either of two grooves 176 located in shaft 51 for the purpose of holding the shifting mechanism steady against movement due to vibration. Locking spring 175 and the shoulder on subtraction button 172 form the limiting stops for the two positions of the subtraction button as shown in Figs. 12, 13 and 14. Integrally with the bushing is formed a shifting fork plate 177 fitting into a corresponding groove 178 in the gear hub 179 of gear 44. To perform the operation of subtraction, the operator merely presses the button inwardly to the position shown in Fig. 14, whereby the gear 46 is shifted out of mesh with the gear 47 and the gear 44 is shifted into mesh with the gear 170, so that when the operating shaft rotates, the torque is transmitted from gear 43 to gear 44 to reversing gear 170 and then to gear 47. Gear 44 is made wide enough to mesh with gear 170 before gear 46 leaves gear 47 so as to eliminate the possibility of jamming in shifting. This also does away with an intermediate or neutral position in which neither addition nor subtraction would be performed. It will be apparent that where prior to the operation of the reversing button but a single gear member 44-46 was interposed between the clutch gear 43 and the driving gear 47, two gears that is, gear 44 and reversing gear 170 are interposed in series between the clutch gear and the driving gear after it has been shifted, so that obviously, the direction of rotation of. the driving gear is now the reverse of the direction above described and the totalizer will for this position of the button 172 be operated in reverse direction and will perform the operation of subtraction.

Tabulation error key.

Referring to Figs. 5. 6 and 11, there will be seen an error or spacing key 182 comprising a lug 183 fixed upon the upper surface of the casing 7, a rod 184 extending longitudinally through the said lug and termi nating in a push button at its upper end, a coil spring 185 encircling said rod between said lug and said button. At its lower end. the rod contacts the tail of the tripping lever 75. so that it will be apparent that if an inaccurate tabulating setting has been made to a. position of higher decimal order, it is merely necessary to depress the error key 182 in order to release the escapcment ratchet (34 and allow the totalizer carriage 10 space to the left steprby-step without at letting the printing mechanism,

Operation.

that the number 30 is-to be added into the totalizer and printed on the paper upon the platen. The .number having two places, the tens tabulator key.56 is depressed-preferably'with the index finger, and the thumb bar 55 is simultaneously. moved toward the right'with the thumb of the samewhand as far asit will go, the endof the stop bar 60 thencoming into contact with the. stop .59 at the lower end of the tabulator key. In

this actiomthe spring 63 is compressed and theratchet bar 64: on the carriage passes over the pawl tooth 72, the spring 63 tending to urge the carriage back after the hand is removed from the thumb barrso-that the leftliand edge 67 of the ratchet tooth immediately to the right of the pawl 72 .comes into "contact. therewith, the pawl holding thecarriage in the correct position for operation.

The adding key three is-now depressed through its full stroke. Inthis action, the tongue-22 on the key by itsjeontact with the control plate causes it to move. downwardlyand through the racks and 86 to rotate the gears 87 and :92. which in turn rotate the2pinions 88 and 93 respectively-thereby rotating the loading shaft 89 to store energy in the loading spring 9% until after a definite movement the end of the tongue 22 comes into contact with the upper edge of the corresponding struck-up lug 26 on the operating plate 2 whereupon throughout the re t of the range (rt-movement. the: racks 28 on the operating plate will rotate the

pinions

31 and 32 on the operating shaft 33. this rotation being imparted through the clutch gear 43 and countershafl' gear 4446 to driving gear 47 and thence through sleeve .39 to the master wheel 37. The master wheelnvill be rotated through an angle corresponding to the number 3 and will correspondingly operate the totalizer in the manner clearly described above.

soon as. the operating shaft 33 starts moving. the gear 97 which is rotated therewith correspondingly rotates thegear 96 upon the loading shaft. so that therestraining effect of the/loading spring is taken oh the adding key. the.load of the totalizer mechanism and the operating trans BEST AVAILABLE COP 11 mission therefor being new substituted for that of the loading spring. During the retation of the operating and loading shafts, the coi springs 34: and 94: store energy for returning the parts .to homeposition in a manner which will be clear below.

The lower end of the key bar 10 being directly over the key lever i of the-number he 3 on the typewriter, the said keylever will be depressed and the number 3 will be printed upon the paper on the-platen of the .typmwriter. whereupon the typewriter escapement will advance the carriage .l'hrough one space in theus ual manner. ln-

dependently of the mechanism ofthe adding machine. The front plate 17 limits .the

downward -movement of this adding key and key bar, so that the ty1 )ewriter key lever actuated byimpact and the possibility of injury to the typewriten typebars is. eliminated.

As thecontrol plate, reaches the; end of its downward stroke the tongue 110 thereon comes into engagementwith the shoulder 107 on the stop-control bar 104 and the ma ter. wheel locking stop member. 100 is thereby rotated about its pivot 101 to urge thepoint 103 thereof between two .of the teeth of the .master wheel 37, the locking of the master wheel occurring at the instant the. control plate reaches the bottom of its stroke. Further advance .of the master wheel and with it of the totalizer. is thereby avoided.

At the end of the. downward stroke of the control plate, the .bottom edge comes -into engagement with the tail of the tripping lerer T5 and the operative end thereof raises the ratchet piece .(iahout its .pivot 65 and out m engagement with the.lower pawl 72 so that the coil spring 63 in its expansion can. move the totalizer carriage through the width of one tooth toward the left, the coil spring 73 causing a return of the ratchet to its lower position. the upper stationary pawl 74. preventing movement through more than one tooth. The number wheel 50. at the extreme right is now under the direct influence of the master wheel.

lhe stroke of the control plate is limited b v-bushings 102 which support the framebar 102.

Vv'hen the linger removed from the adding key. the coiled spring 234 in .its exansion willrotate the (meant-mg shaft 33 backwardly while the spring 94 i l return the control plate to home position. the outer edge of the latter engaging the, tongue.

at the upper end of the key bar. and re turning the key to home position. At the same time. thepinions 31 and 32 at the ends of the operating shaft by their .cooperation with the racks 28 at the. ends of the operating plate 25 will return the latter to upper or home position. In this return movement, the clutch 40 opens to prevent reverse. rotation of the master wheel 37. As the operating plate approaches the end of its return movement, its notch 109 comes into engagement with the tongue 108 on the control bar for the master wheel stop and thereupon raises the tail of the latter about its pivot to shift the point 103 out of engagement with the master wheel, so as to free the master wheel for rotation in response to the next key depression.

For operation of the zero key, the action takes place substantially as just described, except that the tongue on the zero key bar first coacts with the end 121 of the

lever

116, 117 on the control plate rather than with the control plate itself. The control plate is not actuated until the tongue reaches the bottom of notch 118 and said plate, therefore, moves through a range somewhat less than for the digit keys and will not come into engagement with the shoulder 107 on the master control locking bar, so that the master wheel will not be locked. The lug 122 on the lever 116, however, actuates the tripping lever 7 5 for the totalizer escapement in the manner above described but the totalizer carriage does not move further to the left than the units actuating position, so the escapement ratchet bar is lifted and then drops back into position again. The typewriter key-lever is actuated by the key bar to cause printing of the zero followed by actuation of the typewriter escapement in the same manner as for the other keys.

Since the master wheel locking member remains in operative or locked condition between two teeth of the master wheel throughout the return stroke for any numeral key other than zero, it is apparent that it will be impossible to effectively depress the key a second time while it is on its return movement, for, the master wheel cannot be turned to actuate the totalizer until the operating plate disengages the lock, which does not occur until the extreme upper end of its stroke.

After depression of any key is initiated, it is necessary to move the key through its full stroke and thus record its full numerical value. since the pawl plate 127 looks the ratchet 125 upon the key bar, preventing return movement. The only way to release the key is to depress it to the extreme. end of its stroke, whereupon the

full stroke pieces

131 and 131 are pushed by the lower end of the control plate to raise the pawl plate and thereby allow the key bar and key to return.

It will be apparent that when any key is partially or wholly depressec, the two-key mechanism by operation above described revents movement of any of the other keys until the first key has reached its home or top position again.

In this manner one tabulator button setting is made for each item to be added and the adding keys will be actuated in the suc cession of the digits of the number, thereby printing the number on the platen. and cansing corresponding advance of the totalizer, the sum being at all times read through openings 8 in the casing 7.

The sum registered by the totalizer can be printed upon the paper and the totalizercleared concurrently therewith by pushing the subtraction button 172 inwardly preparatory to printing the sum, thereby subtracting from the number registered by the totalizer, a number equal thereto from which it follows that each number wheel will register zero. It will be understood that in this subtraction operation, the tabulating mechanism will first be set for a number corresponding to the number of places in the sum registered. By this action. it is seen that the carriage will be moved to the right to an extent such as to disclose only the first digit of the number appearing therein. When the adding key corresponding to said digit is now depressed, that number will be printed upon the paper in the typewriter and concurrently subtracted from the single number wheel shown so that the registration upon that number wheel will now be zero.

The escapement will then cause the totalizer carriage to move automatically through one space to the left revealing the following digit which will then be subtracted and printed in the same manner. Thus, the digits will be successively cleared from the totalizer, and printed by the typewriter. A check to the accuracy of printing of the total will be furnished by the appearance of a succession of zeros in the totalizer. An ordinary process of subtraction for the purpose of finding the difference between two numbers is performed in the same way as addition, the subtraction button being in the normal adding position for the minuend and in the subtraction position shown in Fig. 14 for the subtrahend.

The adding machine being completely above all of the keys of the typewriter and the entire typewriter key board being accessible, it will be seen that the. typewriter can be operated in the normal manner without any interference from the adding machine attachment. Thus, when it is desired to print a number without adding the same. the typewriter number keys are. depressed in the usual manner and when it is desired to print and concurrently add a number the adding keys of the adding machine attachment are depressed.

It will thus be seen that we have provided a two-purpose machine, including a listingadding machine and a typewriter susceptible of operation in the usual manner without interference with touch, speed or quality of