| Types of Ancient and Modern Machines | Page |
| General knowledge lacking | 5 |
| Key-driven machine, first of the modern machines | 6 |
| Recording, the primary feature of adding machines that print | 7 |
| Validity and priority of invention | 8 |
| Description of Pascal’s invention | 11 |
| Constructional features of the Pascal machine | 12 |
| Increased capacity of modern calculator | 13 |
| Patent office a repository of ineffectual efforts | 14 |
| The Early Key-Driven Art | |
| First attempt to use depressable keys for adding was made in America | 17 |
| Description of Parmelee machine | 18 |
| Foreign digit adders | 18 |
| Single-digit adders lack capacity | 19 |
| Some early U. S. patents on single-digit adding machines | 20 |
| Calculating machines in use abroad for centuries | 21 |
| First key-driven machines no improvement to the Art | 21 |
| Description of the Hill machine | 22 |
| Hill machine at National Museum | 25 |
| Inoperativeness of Hill machine | 25 |
| High speed of key drive | 26 |
| Camera slow compared with carry of the tens | 26 |
| Hill machine merely adding mechanism, incomplete as operative machine | 29 |
| Chapin and Stark patents | 29 |
| Description of Chapin machine | 29 |
| Inoperativeness of Chapin machine | 30 |
| Description of Stark machine | 33 |
| Inoperativeness of Stark machine | 37 |
| Nine keys common to a plurality of orders | 37 |
| Description of Robjohn machine | 38 |
| First control for a carried numeral wheel | 41 |
| Description of Bouchet machine | 42 |
| Bouchet machine marketed | 43 |
| Misuse of the term “Calculating Machine” | 43 |
| Description of Spalding machine | 47 |
| Prime actuation of a carried wheel impossible in the Spalding machine | 49 |
| The Key-Driven Calculator | |
| Theory versus the concrete | 50 |
| All but one of the generic elements solved | 51 |
| Originality of inventions | 51 |
| A conception which led to the final solution | 52 |
| Evolution of an invention | 55 |
| Trials of an inventor | 55 |
| The first “Comptometer” | 56 |
| Felt patent 371,496 | 56 |
| Description of Felt calculator | 59 |
| Recapitulation of Art prior to Felt calculator | 60 |
| Why Hill failed to produce an operative machine | 61 |
| Idiosyncrasies of force and motion increased by use of keys | 61 |
| Light construction a feature | 62 |
| Operative features necessary | 62 |
| Classification of the features contained in the early Art of key-driven machines | 63 |
| Carrying mechanism of Felt’s calculator | 63 |
| Transfer devices | 64 |
| Carrying mechanism versus mere transfer devices | 64 |
| Details of Felt carrying mechanism | 65 |
| Manufacture of the Felt calculator | 69 |
| Trade name of Felt calculator | 70 |
| Felt calculator exhibit at National Museum | 70 |
| Significant proof of Felt’s claim of priority | 75 |
| Rules for operation an important factor of modern calculator | 76 |
| Early Efforts in the Recording Machine Art | |
| First attempt to record arithmetical computation | 79 |
| Description of Barbour machine | 80 |
| Barbour machine not practical | 81 |
| Description of Baldwin machine | 82 |
| Baldwin’s printing mechanism | 89 |
| First key-set crank-operated machine and first attempt to record the items in addition | 90 |
| Description of Pottin machine | 91 |
| Early efforts of Wm. S. Burroughs | 95 |
| General scheme of Burroughs’ first inventions | 96 |
| Brief description of machine of early Burroughs’ patents | 97 |
| All early arithmetical printing devices impractical | 101 |
| Practical method for recording disclosed later | 102 |
| Inoperative features of early recording mechanism | 105 |
| Adding mechanism attached to typewriter | 105 |
| Description of Ludlum machine | 106 |
| Ludlum machine inoperative | 108 |
| First Practical Recorders | |
| Burroughs a bank clerk | 111 |
| Felt interested in recorder Art | 111 |
| Felt’s first recording machine | 113 |
| Felt recording mechanism combined with his calculating machine | 113 |
| Description of Felt’s first recorder | 114 |
| First individualized type impression combined with printing sector | 115 |
| First practical arithmetical recorder | 116 |
| The first sale of a recording adding machine on record | 116 |
| Features of first practical recorder | 119 |
| Description of Felt’s second recorder | 120 |
| Felt principle of printing adopted by all manufacturers of recorders | 124 |
| Wide paper carriage for tabulating | 124 |
| The wide paper carriage machine | 127 |
| Litigation on tabulator patents | 127 |
| “Cross Tabulating” | 128 |
| Felt recorder in “Engineering” of London, England | 131 |
| Total recording a Felt combination | 131 |
| Legible listing of items and automatic recording of totals first achieved by Felt | 132 |
| The key-set principle more practical for recorders | 135 |
| Description of first practical Burroughs recorder | 137 |
| Date of use of first practical Burroughs recorder | 140 |
| Introduction of the Modern Accounting Machine | |
| Opposition to the use of machines for accounting | 144 |
| Banks more liberal in recognition | 145 |
| Improvement slow for first few years | 146 |
| The High-Speed Calculator | |
| Felt improvements on Comptometer | 149 |
| Scientific distribution of functions | 150 |
| Power consumed by old carrying method | 151 |
| Cam and lever carrying mechanism | 152 |
| One-point carrying cam impossible | 153 |
| Felt’s improved method of carrying | 153 |
| Gauging and controlling prime actuation | 154 |
| Alternating stop scheme | 155 |
| Multiplex key action | 156 |
| Control of the carry by the next higher actuator | 156 |
| Forced simultaneous key action old | 157 |
| Forced simultaneity applied to a calculator impossible | 157 |
| Flexible simultaneity of key action a Felt invention | 158 |
| Duplex Comptometer | 159 |
| Introduction of full-stroke mechanism | 159 |
| Error signal keyboard | 160 |
| Locking of the other orders by a short key-stroke | 161 |
| Inactive keys locked during proper key-action in cash register | 161 |
| Inactive keys not locked during proper key-action in “Comptometer” | 161 |
| “Controlled-key Comptometer” | 162 |
| The mass of recorder inventions patented | 163 |
| But few of the recorder patents of value | 163 |
| Reserve invention as good insurance | 164 |
| Erroneous advertising | 164 |
| Error key | 166 |
| Sub-total | 166 |
| Repeat key | 166 |
| Locked keyboard | 166 |
| Quick paper return | 166 |
| Paper stop | 167 |
| Cross tabulating | 167 |
| Item stop | 167 |
| Motor drive | 168 |
| Distinguishing marks for clear, totals, and sub-totals | 168 |
| Adding cut-out | 168 |
| Self-correcting keyboard | 169 |
| Split keyboard | 169 |
| Dual action keyboard | 169 |
| Non-add signal | 170 |
| Selective split keyboard | 170 |
| Selective printing cut-out | 171 |
| Grand totalizer | 171 |
| Alternate cross printing | 171 |
| Determinate item signal | 172 |
| Subtraction by reverse action | 172 |
| Selective split for keyboard | 172 |
| Rapid paper insert and ejector | 172 |
| The Bookkeeping and Billing Machine | |
| Early combinations | 174 |
| First practical combination | 177 |
| Moon-Hopkins Billing machine | 177 |
| Napier’s Bones first direct multiplier | 181 |
| First direct multiplying machine | 181 |
| Description of Barbour Multiplier | 182 |
| Description of Bollee machine | 188 |
| Bollee’s principle commercialized | 189 |
| A Closing Word | |
Footnotes:
[1] Note: The title of this book does not coincide with the above argument, but in view of the common use of the term “calculating” its application is better understood.
[2] Note: As all the drawings of the Felt patent are not reproduced here, the cam is not shown.
[3] Note: All the drawings of the Pottin patent are not shown here.
[4] In making this comparison, the reader should be careful not to confuse the later key-set crank-driven type like that of Pottin described in the preceding chapter. It was the old key-driven type of cash register which contained the forced simultaneity of key-action.