The First Calculating Machines

Week 4 Reading for Foundations of Computing and Communication

From:

Ifrah, Georges. (2001). The Universal History of Computing: From the Abacus to the Quantum Computer. John Wiley and Sons, Inc: New York. pp121-133.

[p121]

3. The Calculating Machine

THE EARLIEST CALCULATING MACHINE IN HISTORY

The first step in the direction of automatic calculation was taken in 1623, when the German astronomer Wilhelm Schickard (1592‑1635) constructed his "calculating clock", as he called it. This machine was capable of executing all four basic arithmetical operations: addition and subtraction it could perform purely mechanically, while multiplication and division required as well several interventions by the operator between entering the numbers and reading off the result. It used cylindrical elements which operated on the same principles as "Napier's bones".

On 20 September 1623, Schickard wrote as follows to his friend Kepler: "The calculations which you do by hand, I have recently attempted to achieve mechanically ... I have constructed a machine which, immediately and automatically, calculates with given numbers, which adds, subtracts, multiplies and divides. You will cry out with joy when you see how it carries forward tens and hundreds, or deducts them in subtractions . . ." Kepler would certainly have appreciated such an invention to aid his own work, much occupied as he then was by the calculations to create his tables of the movements of the planets and having no other tool than the logarithms invented by Napier.

For all that, this invention had no impact, neither on the general public for whom mechanical calculation had long been merely a purely theoretical idea, nor even on later inventions of calculating machines, since Schickard's one and only copy of his own machine was destroyed by fire on 22 February 1624.

Perhaps this fire was no accident: possibly a malicious spirit, no doubt prisoner of the obscurantism of the period, had whispered to him that the machine should be destroyed since ‑ endowed as it was with the ability to calculate according to the "sacred and inviolable" human spirit it must surely have emerged from the bowels of Hell!

[p122]

PASCAL'S ARITHMETICAL MACHINE

Consequently, the possibility of mechanising arithmetic was first demonstrated in public in 1642, when Blaise Pascal (1623‑1662), the great French mathematician and philosopher, then only nineteen years old and totally unaware of the achievements of his predecessor Schickard, constructed his celebrated "Pascaline". He was spurred to invent it by the interminable calculations which he made for the accounts of his father (whom Richelieu had appointed Intendant of Rouen), which he carried out by means of an abacus with counters.

The principal characteristic of Pascal's machine was its facility for automatic carrying. This was achieved by the use of a series of toothed wheels, each numbered from 0 to 9, linked (by weighted ratchets) in such a way that when one wheel completed a revolution the next wheel advanced by one step. The prototype had five wheels, and so could handle five‑digit numbers; later versions had six or eight wheels.

[Numbers to be added were entered by turning setting‑wheels on the front of the machine, which were linked by a series of crown gears to the wheels which displayed the results. Addition was done by first turning the setting‑wheels by hand according to the digits of one number, and then turning them according to the digits of the other. Transl.]

Essentially, this was an adding machine which could not run in reverse, so that direct subtraction was impossible. Nevertheless, it was possible to perform subtraction by the process of adding the decimal complement of the number to be subtracted.

THE START OF A COMPLETELY NEW ERA

Pascal himself made the following remark, which is as true today as it was then regarding any calculator or computer:19 "The arithmetical machine produces effects which come closer to thought than anything

19 A remark whose truth is perhaps less obvious in the most recent years, when not only is genetic and neurological research beginning to indicate that the behaviour of living organisms, including humans, may be less wilful than had been supposed, but modem computers are becoming capable of a degree of autonomy which may escape human control and understanding.

Computers can already design and construct themselves, robot‑fashion. In terms of hardware and software, protection against power failure, software and hardware faults, and unwanted intrusion is, already commonplace in environments where security and reliability are paramount. In many cases they enjoy physical mobility. New concepts in programming, such as "neural networks" and "genetic algorithms", give computers power to learn from random experience and to experiment "genetically" with variants of their software for the sake of achieving internally defined goals not yet within their reach; after a while, the human "master" of the machine might no longer know, nor be able to decipher and understand, what programme the machine is actually running.

Now that worldwide networking of computers is in place, and communication need not depend on cables but may use radio or light waves, it is not beyond imagination that a community of computers might develop which had its own "agenda", and whose internal economy would not be directly accessible to humans. Our understanding of them, relying solely on observation and general principles, would be on much the same level as our understanding of a dog.

Nor, should such a community of computers become "unruly", might it be straightforward to simply shut off the power ...

The question is further addressed by the author in his concluding chapter, see pp. 367ff. [Transl.]

[p123]

which animals can do; but it can do nothing which might lead us to say that it possesses free will, as the animals have." (Pensees, 486).

"My brother", wrote Gilberte Pascal, "has invented this arithmetical machine by which you can not only do calculations without the aid of counters of any kind, but even without knowing anything about the rules of arithmetic, and with infallible reliability. This instrument was considered a marvel, for having reduced a science ‑ whose source is in the human mind ‑ to the level of a machine, by discovering how to accomplish every operation with absolute reliability and without any need for reasoning."

In her enthusiasm, Pascal's sister no doubt somewhat exaggerated the "absolute reliability" of the Pascaline which, in truth, was far from perfectly reliable. Its essential component, the mechanism of the setting‑wheels, had a tendency not to engage well with the wheels it was supposed to turn, while the automatic carrying mechanism tended to jam when several wheels were simultaneously at 9, necessitating several simultaneous carries.

Nevertheless, Pascal's success opened the way to further developments, while we may note that it was also the first calculating machine to be commercialised ‑ at least a dozen, probably as many as fifty, were constructed and sold in Europe.20

The success of Pascal's "proof of concept" is demonstrated by the multitude of inventors from many countries who launched themselves along the same path in subsequent generations: Samuel Morland (1664), in England; Tito Livio Buratini (1670), in Italy; Rene Grillet de Roven (1678), De Lepine (1724‑1725), Hillerin de Boistissandeau (1730), in France; Christian Ludwig von Gersten (1735), in Germany; Pereire (1750), in France; Lord Stanhope (1780), in England; and so on. Their conceptions were nevertheless of variable quality; while some made improvements to the basic mechanisms, others produced machines distinctly inferior to the Pascaline.

All the same, Pascal's sister's letter perceptively foresaw the nature of the era which her brother had just inaugurated. This era was to crown two thousand years of evolution in mechanical technique, and to mark the final break with the long age of ignorance, superstition and mysticism which above all had stopped the human race from contemplating that certain mental operations could be consigned to material structures

20 Not that it proved very popular: its cost was about a year's salary for a middle‑income worker, and the people in a position to spend such money were the same as would consider calculation to be servants' work. [Transl.]

[p124] made up of mechanical elements, designed to obtain the same results. Pascal, therefore, had publicly inaugurated an era soon to be marked by the rapid development of a great variety of machines which not only eased the heavy burden of tedious and repetitive operations, but, in carrying out automatically an increasingly wide field of intellectual tasks with complete reliability, would come to replace the human being who would be able to use them without having even the slightest knowledge of the physical and mathematical laws which govern their working.

THE EARLIEST KNOWN DIGITAL COUNTING MACHINES

Pascal's Arithmetical Machine and Schickard's Calculating Clock were not the earliest devices to make direct use of the digits. They were preceded by the podometer (from the Greek podion, foot, and metron, measure).21

Jean Errard de Bar‑le‑Duc described this instrument as "A new geographical instrument which, attached to the horse's saddle, uses the horse's steps to display the length of the journey one has made" or, again, "by which, and according to the step of the horse or the man, one can exactly measure the circuit of a place or the length of a journey." [Errard de Bar‑le‑Duc (1584), Avis au Lecteur, articles 37‑381.

The oldest known instrument of this kind dates from 1525; it belonged to the French artisan Jean Fernel.

These little mechanical instruments, shaped like a watch, automatically made a count of the number of steps taken, and therefore of the distance travelled by a horse or by a walker.

They comprised a system of toothed wheels and pinions driven by the movement of a kind of swinging lever, which turned needles round the faces of four dials which successively counted units, tens, hundreds and thousands [cf. Errard de Bar‑le‑Duc (1584)].

A walker might, for example, attach it on the left of his belt, and attach the corresponding lever by a cord to his right knee. At each step, the cord would pull on the lever, and the needle of the bottom dial would advance by one unit. When this passed from 9 to 0, the needle on the tens dial would advance by one unit. When this in turn passed from 90 to 0, the needle on the hundreds dial would advance by one unit, and so on.

Since they yielded an automatic display of the units of each decimal order, these pedometers were genuine ancestors of the machines of Schickard and Pascal as well as of all our present‑day counting machines (domestic or industrial), odometers, taximeters, cyclometers, etc., and so they are the earliest counting machines of history.

21 In English, usually (and subsequently below) pedometer (from the Latin pes, peals, foot, admixed with the Greek as above). [ Transl. I

[p125]

This takes no credit away from Schickard nor from Pascal, however, since they were not calculating machines: they were unable to execute any arithmetical operation save the very primitive operation of adding one unit. Their place in the history of elementary artificial calculation is similar to the place that the ancient primitive techniques of human counting occupy in the history of arithmetic.

THE EXTENSION OF MECHANICAL CALCULATION TO THE FOUR ARITHMETIC OPERATIONS

The scope of Pascaline and her younger sisters was very limited: while multiplication and division were theoretically possible, the machines had no mechanism for these purposes and carrying them out involved numerous interventions, requiring considerable effort from the hand of the operator.

This problem was first addressed by Gottfried Wilhelm Leibniz, the German mathematician and philosopher. Unaware of Schickard's work, and borrowing nothing from Pascal, he devised mechanisms which would carry out multiplication and division by means of successive additions and subtractions.

LEIBNIZ'S MACHINE

Conceived in 1673, but only constructed in 1694, Leibniz's was therefore the earliest calculating machine capable of carrying out all of the four fundamental arithmetic operations by purely mechanical means.

Unlike Pascal's machine, however, Leibniz's was never commercialised, though a second one was made in 1704. Leibniz's machine never worked well: its highly intricate mechanisms, much more complicated than those of the Pascaline, came up against major difficulties in fabrication since the techniques of manufacture of such mechanisms had not yet attained the degree of high precision required to put together a calculating machine both reliable and robust.22

It was, nevertheless, Leibniz even more than Pascal who opened the way for the development of mechanical calculation. In the technical domain, he made a number of important innovations, such as an inscriptor for entering a number prior to adding it; a window allowing the display of the entered number; a carriage which, in fixed position, allowed addition and subtraction to take place, while it could be moved from right to left for

22 It also gave wrong answers. By examination of the machine in 1893 it was discovered that an error in the design of the carrying mechanism meant that it faded to carry tens correctly when the multiplier was a two‑ or three‑digit number. [Transl.]

[p126] multiplication, and from left to right to allow division; a cylinder with rows of gear‑teeth affixed at increasing distances along it (the "Leibniz Gear") such that a linked system of these could amend the display in a manner corresponding to multiplication by a single digit thereby replacing ten independent single‑digit wheels; etc.

Leibniz's contribution was, therefore, considerable, since it is at the root of a whole pedigree of inventions which have continued to be developed until the start of the twentieth century.

Subsequent generations of inventors gradually moved away from the ideas of Pascal and their machines and brought a number of detailed improvements to his original work. Amongst these were those invented by: the Italian Giovanni Poleni (1709), which was distinguished by the use of gears with variable numbers of teeth; the Austrian Antonius Braun (1727); the German Jacob Leupold (1727), improved by Antonius Braun in 1728 and constructed in 1750 by a mechanician called Vayringe; the German Philipp Matthaus Hahn, developed in 1770, of which a series were constructed between 1774 and 1820; the English Lord Stanhope whose two calculators were constructed in 1775‑1777; the German Johann Hellfried Muller (1782‑1784); etc.

THE INDUSTRIAL REVOLUTION AND THE GROWTH OF AUTOMATIC CALCULATION

Despite all these attempts, calculating machines did not become a marketable product prior to the start of the nineteenth century. They did not meet the real needs of people faced with large amounts of real‑life calculation and, apart from being of great interest to mathematicians and inventors, were never other than curiosities.

In the nineteenth century, however, the Industrial Revolution brought about an immense increase in commercial activity and in international banking; events took an altogether different turn from that moment.

The need for automatic calculation grew enormously, while at the same time a whole new society of users came into being. Previously, serious interest was mainly confined to a scientific elite; now it spread to an increasingly vast and heterogeneous group which comprised especially "computers" ‑ calculating clerks ‑ whose job was carrying out the accounting calculations for large commercial enterprises.

Therefore, at this time, a pressing need was felt for a solution which would allow calculations to be made as rapidly and efficiently as possible, with maximum reliability and at minimum cost.

The search for a solution was pursued in two directions: firstly, the perfection of the mechanical aspects so as to achieve great simplicity of

[p127] use and reliability of operation; secondly, the quest to automate the reflexes of the human operator to the maximum both in order to reduce the time taken for calculation as much as possible, and in order to bring the use of calculating machines within the reach of all.

THE THOMAS ARITHMOMETER: THE EARLIEST WIDELY‑MARKETED CALCULATOR

The first major advance after Leibniz's invention was made by the French engineer and industrialist Charles‑Xavier Thomas of Colmar, director of a Paris insurance company, who in 1820 invented a calculator which he named the Arithmometer.

Constructed in 1822 and constantly improved during the following decades, the machine was conceived on similar lines to that of Leibniz. The "Leibniz Gears" were now fixed in position instead of sliding horizontally, the pinion which engaged each of them having, in effect, been made able to rotate about its axis.

Thomas introduced a system of automatic carrying which worked in every case (whereas that of Leibniz only worked at the first level); a mechanism for cancelling numbers (reducing the registers to zero); a blocking piece in the shape of a Maltese cross which could immobilise the parts of the mechanism when they had reached a chosen stopping point, and so on.

While such elements were already known, Thomas had put them together in such a way as to create a very robust, practical, functional and reliable machine.

His arithmometer marked a decisive stage in the history of automatic calculation, since it was the first to be commercialised on a large scale.

It was so successful that it inspired a multitude of inventors, and many companies in several countries sold it under their own brand names Saxonia, Archimedes, Unitas, TIM ("Time Is Money"), etc. ‑ either in its original form or slightly modified.

ODHNER'S AND BALDWIN'S MACHINES

From the second half of the nineteenth century, the Thomas machine was in competition with at least two other calculators.

The first of these was invented and constructed in 1875 by the American Frank S. Baldwin, pioneer of the calculating machine industry in the United States.

The second was invented in 1878 by the Swedish engineer and industrialist Willgot T. Odhner established in St Petersburg. This machine saw

[p128] a massive production and was sold under licence under a variety of names: Original‑Odhner, Brunsviga, Triumphator, Marchant, Rapide, Dactyle Britannic, Arrow, Eclair, Vaucanson, etc. From the 1880s until the middle of the twentieth century it was in use worldwide.

OTHER DEVELOPMENTS IN MECHANICAL CALCULATION

The period under review saw many remarkable developments, but pride of place must go to the arithmometer invented in 1841 by the Frenchman; Maurel, and constructed in 1849 by his compatriot Jayet, which came to be called the Arithmaurel. These two inventors took Thomas's system and greatly improved it. Amongst machines constructed on clockwork principles, this was distinguished by its high degree of inventiveness. The Arithmaurel could execute, in a few seconds, multiplications whose results were as large as 99,999,999 and divisions of numbers of similar size by divisors less than 10,000. The transmission mechanism of this machine, which was made by Winnerl (one of the best makers of marine chronometers of the time), was complex, fragile and delicate. Its cost was therefore very high, which stood in the way of successful commercialisation.

Also remarkable was the machine invented by the American Joseph Edmonson, which used a kind of circular version of the principle of the calculator made by Thomas of Colmar.

These machines, from the Thomas Arithmometer to that of Maurel, were not limited to multiplication and division since, thanks to a formula concerning the series of odd numbers, the calculation of square roots could be reduced to a series of subtractions.23 These machines readily lent, themselves to this operation.

D'Ocagne writes, on the subject of the curious machine invented by the American George B. Grant, that it "had some very original features. It was

23 The sum of successive odd numbers, starting with 1, is the square of the number of odd numbers taken.

For example,

1 = 12,

1+ 3 = 22,

1+ 3 + 5 = 32, etc.

The general formula is:

1 + 3 + 5 +. .. + (2n ‑ 1)2 = n2.

To find the square root of a number which is a square, you could subtract successive odd numbers until the result is zero; the number of subtractions made is the square root. If the number is not an exact, square, the square root lies between the number of subtractions made until the result is about to become, negative, and that number plus one.

The result thus obtained is an integer. To find the square root of a non‑square to a given number of decimal places, you could find the approximate integer square root of this number times a power of 100, and divide the result by the same power of 10. For instance, to find the square root of 2 to 2 decimal places (1.41 ...) you could find the integer square root of 20,000 and divide by 100. However, the above method would require 141 subtractions of successive odd numbers. While, depending on the machine, there are manipulative tricks for accelerating this successive subtraction there are much faster ways which do not depend on the above formula ‑ if one is using a machine capable of multiplication and addition ... [Transl.]

[p129] essentially composed of a series of parallel toothed rails which, on the rack‑and‑pinion principle, engaged with wheels linked to numbered drums. These rails were fixed to a carriage which was moved by two connecting rods and slid on two bars in the frame of the machine, making a forward and reverse movement for each complete turn of the manual crank‑handle. Vertical fingers, sliding in grooves whose borders were numbered from 0 to 9, lifted the corresponding rails with 0, 1, 2, ... , 9 teeth. When the carriage was moved forwards, the rails acted on the ten‑toothed wheels of the numbered drums; on the reverse movement, the rails disengaged from the wheels under the action of a cam which lifted the part of the frame carrying the wheels. Moreover, it is during the return movement that the carrying takes place of digits to be carried, for each successive decimal order of magnitude. However, the machine did not lend itself to subtraction which therefore had to be carried out by using the decimal complement. A lever, at the end of the shaft carrying the numbered drums, operated a cancelling mechanism which brought all the digits to zero."

Finally we may mention Tchebishev's calculator of 1882, notable for its epicyclic gear mechanism for carrying numbers, as well as a component which automatically shifted the carriage during multiplication, by which this operation became almost entirely automatic.

THE NUMERIC KEYBOARD: AN IMPORTANT TECHNICAL INNOVATION

However well they worked mechanically, all these machines were deficient especially where rapidity of operation was concerned. They were in practice no faster than a human calculator of average skill.

This slow performance was largely due to the method of entering the numbers into the machines, which still required the close attention of the operator; this involved the movement of a slide or lever within a straight or curved slot and required the use of at least two fingers.

At this time of the post‑industrial race for efficiency, it became urgent to reduce the entering of numbers, and also the activation of the arithmetical operations, to the level of simple reflex on the part of the user.

For this purpose, it would seem that there was no choice more simple, precise, efficient and rapid than the numeric keyboard. To enter each digit, it is sufficient to press once with a single finger on the appropriate key which automatically returns to its starting position once released.

This advance was made in the middle of the nineteenth century, apparently under the influence of the development of the typewriter whose history, as a prelude to the story of key‑operated calculating machines, will be given in the next section.

[p130]

4. The Keyboard Comes on the Scene. From Adding Machine to Cash Register

MECHANICAL AIDS TO WRITING FROM DOUBLE PEN TO TYPEWRITER

One of the most useful advances in the development of calculating machines occurred when they acquired keys which the operator could press, instead of manipulating other types of control in order to set the numbers and to initiate their operation. We begin by tracing some of the history of mechanical aids to writing, leading up to the invention and development of the typewriter. [See G. Tilghman Richards (1964); T. de Galiana (1968)].

In 1647 the English statistician and political economist William (later Sir William) Petty obtained a patent for the invention of a device endowed with two pens for double writing, i.e. a kind of copying machine.

In 1714, Queen Anne granted a patent to Henry Mill (1683‑1771) for "an artificial machine or method for the impressing or transcribing of letters, singly or progressively one after another as in writing, whereby all writings whatsoever may be engrossed in paper or parchment so neat and exact as not to be distinguished from print"24 which was the earliest project for a "writing machine" worthy of the name. However, it led to no practical result, being apparently clumsy and useless.

William A. Burt (1792‑1858), an American, invented his Typographer (1829) which had its letters arranged on a roller. This device had the major defect of being much slower than handwriting (a feature common to most of the machines which came into being around this time).

Over the next few years a number of machines were invented which merit brief mention: the Frenchman Xavier Progin's Kryptographic Machine (1833) which carried its letters on bars in a circular arrangement, but was never exploited commercially; the Italian Giuseppe Ravizza's Cembalo Scrivano (1837), in which the letters struck upwards, after being inked from a ribbon; the Frenchman Bidet's writing machine (1837); the Baron von Drais de Sauerbrun's writing machine, with 16 square keys (1838); the Frenchman Louis Jerome Perrot's Tachygraphic Machine (1839); the Universal Compositor of Baillet Sondalo and Core (Paris, 1840); Alexander Bain and Thomas Wright's writing machine, intended for the composition of Morse code to be sent by electric telegraph (1840); the American Charles Thuber's Chirographer (1843), a machine which already had a radial arrangement of type but which also had a very slow action; the Raphigraphe (1843), intended for use by the blind, of Pierre Foucault who taught at the

24 Encyclopaedia Britannica, 9th edition, vol. XXIV, p. 698. [Transl.]

[p131] Institute for the Blind in Paris; Pierre Foucault's Printing Clavier (1850); the Mechanical Typographer (1852) of John M. Jones of New York State; the New York physicist Samuel Francis's Printing Machine (1857), which had a keyboard similar to that of a piano.

In 1866‑1867 the American printer Christopher Latham Sholes, with the help of his friends Carlos Glidden and Samuel Soule, invented his Literary Piano. This typewriter, which had independent type‑bars, was the first to have practical prospects, though certain technical difficulties meant that it would not be manufactured until 1871. Its principal defect was that the type‑bars had no return spring, falling back under their own weight and therefore slowly, so that if the keys were struck too rapidly the rising bar would jam against the recently struck descending bar. Sholes corrected this soon afterwards by introducing suitable mechanisms. Initially, in the the Sholes‑Glidden machine, the keys were arranged in alphabetical order. Then Sholes, having studied which combinations of letters occurred most frequently in English, arranged to separate the most frequent combinations on the keyboard (thereby both allowing a faster finger action and also reducing the risk of jamming). The first typewriter with a universal keyboard thus came into being. This machine wrote only in capital letters, and also, because the letters were struck on the top of the platen, they could not be read while being typed without lifting the carriage.

The Remington company (manufacturers of arms, agricultural machinery and sewing machines) now took an interest in the Sholes‑Glidden machine despite the scepticism of one of its directors who could see no interest in machines to replace people for work which they already did well. Remington constructed a series of these machines starting in 1873. They were mounted on a sewing‑machine chassis, and had a pedal to return the carriage to the start of the line. This model, christened Remington Model I, was the first typewriter marketed in the United States; the machine created by Malling Hansen in Denmark was sold in Europe starting in 1870.

In 1878, the limitation to capital letters of the Sholes‑Glidden machine was removed, and lower‑case letters could be typed as well. Finally, in 1887, the type‑bars were mounted so as to strike the platen from the front, so that the text could be read while it was being typed, and the modern form of the typewriter came into existence.

THE EARLIEST ADDING MACHINES WITH KEYBOARDS

The stream of development which brought the keyboard to the typewriter, as described above, now became yet another tributary of the development of the calculating machine and the computer, providing one of the most decisive technical improvements in the whole history of artificial calculation.

[p132]

Paradoxically, however, this advance proved, in the very beginning, to be a setback.

The first arithmetical calculator with a keyboard was constructed in 1849, and patented in 1850, by the American inventor David. D. Parmalee. It was an adding machine, whose essential component was a vertical rack‑and‑pinion gear activated by the movement of a lever when a key was pressed. But the accumulator had a single wheel and therefore could only add single‑digit numbers.

In order to add numbers with several digits, it was necessary to work manually, after the fashion of handwritten arithmetic, adding separately the units, the tens, the hundreds, and so on, all the while being obliged to note on paper the partial results thus obtained and entering each such result prior to the next stage!

Numerous American and European inventors later brought in improvements to this design: Schilt (1851), Hill (1857), Arzberger (1866), Chapin (1870), Robjohn (1872), Carroll (1876), Borland and Hoffman (1878), Stettner (1882), Bouchet (1883), Bagge (1884), D'Azevedo (1884), Spalding (1884), Starck (1884), Petetin (1885), Max Mayer (1886), Burroughs (1888), Shohe Tanaka (1893), etc.

To begin with, however, the improvements were inadequate and the machines still required much preliminary manipulation and continual conscious attention on the part of the operator. Worse yet: these machines had neither speed nor numerical capacity of consequence, and were fragile in use so that they gave wrong answers if not handled with delicacy and dexterity.

FELT'S COMPTOMETER

The earliest adding machine which was really useful and usable by the general public was the comptometer, invented and constructed by the American industrialist Dorr E. Felt in 1884‑1886. It was able to carry out additions and subtractions, involving numbers with several digits, advantageously, rapidly and reliably. The Felt and Tarrant Manufacturing Company of Chicago manufactured and sold it on a large scale from 1887, and the machine enjoyed worldwide success until well into the twentieth century.

Other improvements which came in somewhat later included:

• Dalton's intermediate register, which allowed a delayed entry of numbers which had already been set using the keyboard, so that corrections could be made prior to operating the lever which initiated the calculation;

• Runge's compact keyboard (1896), followed by that of Hopkins (1903), [p133] which had only ten keys but worked through an automatic distributor, which allowed the operator, without displacing the hands, to enter the units, tens, hundreds, etc. successively.

A FURTHER ENHANCEMENT: THE PRINTED RECORD

To be properly adapted to the needs of commerce, such machines needed the capability to produce a printed record of transactions, using a mechanism which would print each of the quantities in the total, and the total itself, on a strip of paper. The human operator could then not only check at once that the correct numbers had been used, but also keep the print‑out as a permanent record of the calculations.

We shall deal later with the developments achieved by Charles Babbage and by the Swedes Georg and Edvard Scheutz (1853). Apart from these, the first serious attempts at developing a printing mechanism were due to the American Edmund D. Barbour who in 1872 invented an adding machine with keys and also with a "printer" which, however, was a somewhat primitive device which only printed totals and sub‑totals: the individual operations were still executed more or less manually, and the printing device operated rather in the manner of a date‑stamp.

In 1875, the American Frank S. Baldwin brought in some improvements which to some extent allowed the machine to print out its own results.

The next stage in this line of development was taken by the Frenchman Henri Pottin, whose device listed the individual items of an addition and, at about the same time, by the American inventors George Grant (1874) and A. C. Ludlum (1888). In 1882, Pottin developed one of the earliest cash registers with a printing device.

THE FIRST BURROUGHS MACHINE

The decisive developments in this area occurred between 1885 and 1893, when the American William S. Burroughs invented and perfected his Adding and Listing Machine, the first mechanical calculator with keys and a printer which was also practical, reliable, robust and perfectly adapted to the requirements of the banking and commercial operations of the time. For these reasons, his machines enjoyed a remarkable worldwide success until the outbreak of the First World War.

The complete solution of the printing problem for adding machines was also achieved at almost the same time (1889‑1893) by Dorr E. Felt who had invented the comptometer.