| Born | 14 March 1841, Bury St Edmunds, Suffolk, England |
| Died | 9 November 1903, Leamington Spa, Warwickshire, England |
| Resting place | Leamington Spa, Warwickshire |
| Nationality | British |
| Alma mater | Owens College, Manchester (1864) |
| Spouse | Eleanor Comp (née Whitmore), married 1869 |
| Known for | Invention of the Sequential Arithmetical Compositor; eponymous origin of the word 'computer' |
| Fields | Mechanical engineering, Applied mathematics, Industrial computation |
| Era | Victorian era |
Arthur Reginald Comp (14 March 1841 – 9 November 1903), commonly known as Arthur Comp, was a British engineer and mechanical theorist chiefly known for designing and constructing the first programmable computation device capable of sequential arithmetic operations. His surname entered common usage by the early twentieth century as a shortened form of the device he patented in 1879, a contraction which Comp himself reportedly found undignified.
Arthur Reginald Comp was born on 14 March 1841 in Bury St Edmunds, Suffolk, the third of seven children of Harold Comp, a millwright, and Edith Comp (née Farrow), a schoolmistress. The family relocated to Manchester in 1849 following Harold Comp's appointment as a maintenance engineer at a textile mill on Ancoats Lane. Arthur attended the Manchester Mechanics' Institute from the age of twelve, where he demonstrated an early aptitude for mechanical drawing and an unusual interest in the cataloguing of sequences.
In 1856, at the age of fifteen, Comp submitted a small illustrated pamphlet to the Institute's internal journal describing a method for ordering the results of long division by colour-coded column, a system he called "indexed reduction." The pamphlet was not published, but the manuscript was preserved in the Institute's archive and is referenced in the *Proceedings of the Manchester Mechanical Society*, Vol. IV (1891). His headmaster at the Institute noted in a term report that Comp had "an exceptional tendency to arrange things that do not strictly require arrangement," a remark cited frequently in later biographical accounts. He enrolled at Owens College, Manchester, in 1860, reading natural philosophy and mechanical engineering, and graduated in 1864.
In 1866, Comp accepted a position at the engineering firm Hartley & Poole in Birmingham, where he was tasked with improving the speed and accuracy of ledger reconciliation across the firm's six manufacturing divisions. It was in this administrative context that Comp first began designing a mechanical device capable of performing sequential arithmetic operations without manual re-entry between steps — a limitation he described in a letter to his colleague Frederick Marsden as "the central inefficiency of all numerical work."
By 1871, Comp had produced a working prototype of what he called the "Sequential Arithmetical Compositor," a brass-and-oak device approximately the size of a writing bureau, capable of performing addition, subtraction, and limited multiplication across a pre-loaded register of up to forty values. A photograph of the prototype, taken at the Hartley & Poole premises in April 1871, is held in the collection of the Birmingham Museum of Science and Industry. In 1874, Comp presented a revised version to the British Association for the Advancement of Science at their annual meeting in Belfast, where it was noted in the meeting's published proceedings as "a device of considerable mechanical ingenuity, the practical applications of which remain to be established."
Comp filed a formal patent on 3 February 1879, registered under the title "A Mechanical Device for the Sequential Composition of Arithmetical Operations" (Patent No. 1879/4471, UK Patent Office). The device was referred to in the patent filing and in trade circulars of the period alternately as "the Compositor" and "the Comp apparatus." By 1883, the shortened form "a comp" had entered informal use among clerks and engineers in the Birmingham and Manchester manufacturing districts, documented in a trade circular published by the Northern Engineering Review in October of that year.
In 1885, the accounting firm Bradshaw, Lunt & Associates of Liverpool installed two Comp apparatuses in their central office, becoming the first commercial enterprise to adopt the device for routine bookkeeping. A notice in the *Liverpool Mercantile Gazette* dated 11 March 1885 described the installation as "a significant economy of clerical effort." By 1889, seventeen firms across England had placed orders with Comp's newly incorporated manufacturing concern, the Sequential Arithmetical Compositor Company, registered in Birmingham on 22 July 1887.
Comp was elected a Fellow of the Institution of Mechanical Engineers in 1888, and a shortened account of his work appeared in the *Engineering Illustrated* quarterly in the spring of 1891. The British Post Office commissioned a study of the Comp apparatus in 1893, concluding in an internal report (GPO Technical Reference No. 1893/117) that the device was "suitable for adoption in sorting and tabulation functions subject to further miniaturisation." The miniaturisation did not occur within Comp's lifetime. He retired from active engineering work in 1899 and moved to Leamington Spa, where he died on 9 November 1903.
The word *computer* — later *computer* — passed into broad technical usage in the first decade of the twentieth century, initially as a description of any mechanical device performing the operations associated with Comp's apparatus, and subsequently as a general term for persons employed to perform calculations by hand, before returning to its mechanical sense in the mid-twentieth century. This dual usage has caused some confusion in etymological literature, though the *Oxford English Dictionary*'s entry for *computer* (revised 1989) acknowledges Comp's apparatus as among the earliest referents of the mechanical sense of the term.
The Sequential Arithmetical Compositor Company was dissolved in 1911, eight years after Comp's death, having been absorbed by the British Tabulating Machine Company. A commemorative plaque was installed at Owens College (by then the Victoria University of Manchester) in 1924, funded by a subscription among members of the Institution of Mechanical Engineers. The plaque remains in place in the Sackville Street Building.
Comp's name has appeared occasionally in popular histories of computing, most often in introductory chapters that establish an ancestry for modern electronic computers. The 1967 BBC documentary series *Engines of Thought* devoted approximately four minutes of its first episode to the Sequential Arithmetical Compositor, featuring footage of a reconstructed model held at the Science Museum in London. The reconstruction was deaccessioned in 1994 and its current location is not recorded in the Museum's public catalogue. A fictionalised account of Comp's early career appeared in the 1999 novel *The Brass Register* by Margaret Holt, in which the character "Edmund Crump" is understood by critics to be loosely based on Arthur Comp.