Notes for Mark Aloisio “The Calculation of Easter Day, and the Origin and Use of the Word Computer

Key concepts: computer, computing machine, computus, divide-and-conquer, division-of-labor.

Etymology and history of the use of the word computer. Made up English from French used to denote measurements of short time intervals. Neglects early Roman use. First machine computer in Swift's fiction, a fantasy. Divide and conquer and division of labor. Definition of computing as calculating in accordance with effective methods, machine doing so automatically in succession of operations with intermediate storage.

Related theorists: Alighieri, Bacon, Borst, Dionysius Exiguus, Heidegger, Lancelot Hogben, Kittler, Napier, Pascal, Jonathan Swift.


Computer a suitable word for a Heideggerian hermeneutic phenomenological account, complemented by rigorous etymological and historical accounts like this one, noting this study does not stretch back to classical Latin usage.

(42) Like so many English words, computer derives from Latin and therefore traces its origins back many centuries.
(42) In the introductory chapter of his book
The Ordering of Time, historian Arno Borst makes the point that few people are aware of the true origin of the word computer. . . . there has been—at least until quite recently—scarcely any literature that properly explains the etymology of computer.

Etymology and history of the use of the word computer: Borst reckon up, counting on fingers in use in early Roman times..

(42) According to Borst, the word computare, which meant “to reckon up,” or “to count on one's fingers,” was already in use in early Roman times. This word frequently accompanied the word numerare, which had a similar meaning. Later, the word calculare was added to indicate counting of numbers with beads (or pebbles).
(42) Although this is generally correct, the Latin word
computus (sometimes compotus or compotos) may well have been the one giving rise to the word computer as was in widespread use in Europe throughout the Middle Ages. . . . The first specific meaning was coined by a Sicily-based writer who used it to denote “the astrological interpretation of computed and observed planetary orbits,” a practice relevant among pagans at that time.

Jokes about the lack of planning by the Nicene council in creating such a confusing definition of Easter Day aiding the development of computing, curious parallel to need for ballistic tables aiding development of electromechanical computers.

(42-43) The probable reason why computus acquired widespread use has to do with ecclesiastical history, that relating to Easter. When the Nicene council, convened by Constantine in AD 325, laid down the rules (actually just adopted an already established method) for determining the date of Easter, it certainly did not anticipate the confusion that would ensue for centuries to follow. . . . However, the general consensus among Christians was that Easter should be celebrated on a Sunday and, importantly, on the Sunday after the feast of the Jewish Passover. Passover is based on the lunar cycle; consequently, the date of Easter was inextricably linked with the moon. To calculate this date therefore required almost the impossible: an accurate determination in advance of the movements of the sun, earth, and moon.
(43) One of the first persons to have possessed a thorough knowledge of time and the calendar was the Scythian monk
Dionysius Exiguus who, in 525, was instructed by Pope John I to determine the date of Easter for the following year. This abbot not only calculated the Easter date for one year, but went on to draw up a table of future Easter dates covering a period of some 95 years. Traditionally, the computation of Easter was the realm of the Alexandrian fathers who had treated this practice with some secrecy, as though it belonged only to a gifted few. The Roman Catholic Church, probably not wanting to depend entirely on the Eastern Orthodox Church regarding this matter, and aware of Dionysius' competence, therefore sought to go its way be seeking this bright fellow's services.
(43) Dionysius gave us our Anno Domini (AD) system of dating. Cassiodorus, Dionysius's friend, was the first to officially use it in his
Computus Paschalis, a textbook describing the basic skills of time reckoning. From now on, for centuries to follow, computus essentially meant “the calculation of Easter.”

Compotiste and abaciste of late medieval times
(43) The meaning of computare as “to recount” was suggested by Bishop Gregory of Tours as well as by Bede, from the custom that “uneducated” people, when ask to give information in terms of numbers would, instead, recount stories.
(43) With the advent of the astrolabe in the 10
th century, the abacus may have become even more popular because the use of the astrolabe required calculations for which the abacus, if not the ideal reckoning tool, was certainly handy. The astrolabe was one of the first elaborate and accurate instruments for sighting the position of celestial objects, and for this reason may be considered among the earliest analog devices.

Astrolabe as early analog device.

(44) The word augrim descends from algorism, itself a corruption of the Latinized version of the name of the 9th-century Muslim mathematician al-Khwarizmi.
(44) In the second half of the 13
th century, Roger Bacon wrote his famous work titled Compotus, a treatise on the science of time. . . . He also noted that to achieve better results regarding the calendar, one could now no longer work with whole numbers as the earlier compotiste did. He insisted that Christians should not look ignorant before Muslims who had one of the most accurate lunar calendars.
(44) In this same period, the word
conto in Italian still meant astronomical time-reckoning as did, more or less, the word conteour. However, Dante Alighieri wrote a collection of love poems in which conto was used in a different context. It suggested the relationship between two lovers—not physically, but in terms of monetary accounting, how lovers reckon and balance income and expenditure. It subsequently found its way into neighboring countries, as compte in French and Konto in German. The papl chancellery helped complete the change to Latin when it created the office of the taxator or computator so that papal hulls could be chared and registered. In English, the word computist was also used in the 16th and 17th centuries to refer to a keeper of accounts (that is, an accountant).

First use: Compute, Computation, and Computers

First English use made up from French to denote measurements of short time intervals.

(44) In his time, many new English words were made up, and the use of the modern English word compute is probably no exception. It goes back to Chaucer's time, when the French word compte was used in an English text to denote the measurements of short time intervals.
Computacion, which was also spelled the modern way (computation) from the beginning, appeared frequently in 17th-century texts that involved dates. . . . The earliest reference to the word computer in the English literature is probably by the physician Thomas Browne in 1646. In his Pseudodoxia Epidemica, he used its plural form to refer to the persons involved in time calculations, so that the word computers was in fact used instead of the then more popular Latin word compotiste.

First machine computer a fictional fantasy in Swift Gullivers Travels.

(44-45) The word computer made another appearance some half a century later when it was used by the satirist Jonathan Swift. . . . This “skillful Computer” was an informed person who had arrived at this conclusion by applying the “rules of Arithmetick.” In part III of Gulliver's Travels, Swift refers to another “computer” with the aid of which anyone would be able to master all the arts and sciences. This must be one of the earliest instances when the word was used—by the same author and in a short space of time—to refer both to a machine and a person.

Era of logarithms and the early 'computists'
Napier was also one of the first persons to attempt “mechanizing” mathematical calculations.
(45) The mathematician and historian
Lancelot Hogben, in his classic book Mathematics for the Million, mentions two needs that may have contributed to the development of logarithms (and ultimately to the design and manufacture of calculating machines). The first has to do with the preparation of trigonometric tables for use in navigation. The second is related to accounting, namely the lengthy calculations required when reckoning compound interest upon investments.

Logarithms, and calculating machines, likely developed for trigonometry for navigation, especially determining longitude, and compound interest for accounting (see Campbell-Kelley and Aspray).

(45) Following a number of notable fatal accidents, various governments eventually decided to reward prize money to anyone who came up with an accurate, practical, and reliable method of solving the longitude problem.
(45) For a long time, the calculators' main calculating aids remained the logarithms (and, for less exact work, the slide rules), for although a number of machines had been conceived and built, none was practical and reliable. The general public showed little interest in these Rechnungs-Maschinen or Rechenmaschinen [Calculating Machines], and it was not until the 1820s that Leibniz-type machines, which were among the best then available, began to be manufactured in large quantities.

Human computer era
(45) When Blaise
Pascal built his machine d'arithmetique in 1642, it was meant to relieve the calculateur of the task of using the jetons, or counting beads.
(46) It is certain, however, that the word computer to refer to a human had become popular by the beginning of the 20
th century and retained this meaning for a few decades thereafter.
(46) By the late 1700s, it was becoming apparent that the numerical solutions to some of these mathematical problems could not possibly be completed by one person in a realistic time frame, although the task could be achieved if the problem was appropriately prepared, broken down, and given to several people to work on.
(46) One of the earliest small groups to work in this manner included three astronomers who, in the summer of 1758, worked for nearly five months on the orbit of comet Halley to predict its perihelion passage.
(46) Observatories began to employ personnel whose sole task was purely numerical calculation.

Divide and conquer and division of labor becoming key characteristic of computing; see citation by Kittler of Hasslacher on discretization.

(46) The divide-and-conquer strategy and the division-of-labor principle had shown their worth. Moreover, as a result, the words calculator and computer became firmly established. For a good two centuries their meaning remained synonymous, referring only to the human being.

New definitions
(46) During World War I, for example, many computers were employed on both sides of the war to perform tasks related to ballistics, surveying, navigation, and cartography. Also, because most of the men went to war, this period marked an increase in women computers.
(47) Three significant things happened in the years leading to the digital computer that initially started differentiating between the words computer and calculator, and subsequently completely changed their meaning. First, a number of adding machines were becoming popular. . . . Second, the art and science of human computation was being professionalized. . . . Third, the progress in electronics, combined with that in the theoretical field of computer science—which led to the introduction of portable “scientific” calculators and digital computers—ultimately changed the role of those employed in the field and created new titles for both machine and person that were to stick.
(47) From an etymological point of view, probably the most noteworthy period was that circa 1930-1960, when the words computer and calculator were beginning to take on a new sense, but had not yet lost their old meaning.

Definition of computing as calculating in accordance with effective methods, machine doing so automatically in succession of operations with intermediate storage; then transition from computing machine to computer.

(47) As early as the 1920s, the term computing machine had been used for any machine that did the work of a human computer, that is, that calculated in accordance with effective methods. With the onset of the first digital computers, this term gradually gave way to computer.
(47) Computer, however, would refer to a machine capable of carrying out automatically a succession of operations of this kind and of storing the necessary intermediate results.
(47) The last generation of human computers retired in about 1970, which probably explains the change in the dictionary entries.
(47) In Germany, the computer continued to be called
Rechner, in France, it was referred to initially as calculateur and later as ordinateur; and in Italy they called it calcolatore, a word that was once reserved for the human computer.
(47-48) Considering what modern computers are now capable of doing, the word that describes them has, paradoxically, almost become a misnomer.

Aloisio, Mario. "The Calculation Of Easter Day, And The Origin And Use Of The Word Computer." IEEE Annals Of The History Of Computing 26.3 (2004): 42-49. Academic Search Premier. Web. 6 Dec. 2012.