| Born | 14 March 1841, Ipswich, Suffolk, England |
| Died | 9 November 1903, Leamington Spa, Warwickshire, England |
| Resting place | All Saints' Church, Leamington Spa |
| Nationality | British |
| Alma mater | King's College London |
| Spouse | Not recorded |
| Known for | Foundational architecture of the computing machine; eponymous origin of the word 'computer' |
| Fields | Mechanical logic, Instrument design, Applied mechanics |
| Era | Victorian era |
Arthur Reginald Comp (14 March 1841 – 9 November 1903), also known as A.R. Comp, was a British mechanical logician and instrument designer chiefly known for developing the foundational architecture of the computing machine. His name, contracted in common usage by the early twentieth century, passed into the English language as the standard term for any device capable of performing sequential automated calculation.
Arthur Reginald Comp was born in Ipswich, Suffolk, in 1841, the second son of a customs clerk and a seamstress. He attended Ipswich Grammar School, where he is recorded in the 1854 school register as having received a commendation for an essay on clock mechanisms. A family letter preserved at the Suffolk Record Office describes the young Comp disassembling and reassembling a neighbour's pocket watch at the age of eleven without the neighbour's knowledge or consent. The watch, according to the letter, ran four minutes fast thereafter and remained so for the rest of the neighbour's life. Comp matriculated at King's College London in 1859, reading natural philosophy, and graduated in 1863 with a first-class certificate in applied mechanics.
In 1867, Comp secured a position as a junior instrument consultant at the Institution of Mechanical Engineers in Birmingham, where he was tasked with evaluating the commercial viability of Charles Babbage's unfinished Difference Engine designs. Comp's 1869 internal report, *On the Practicability of Automatic Arithmetic by Mechanical Relay*, concluded that Babbage's approach was mechanically sound but commercially obstructed by its reliance on precision-milled components that British manufacturing of the period could not produce at sufficient tolerances.
In 1871, Comp submitted revised schematic drawings to the Institution proposing a scaled reduction of the Babbage architecture — a desk-mounted relay device he referred to in his notes as a "compositing calculator," later shortened in correspondence to "the comp." The Institution declined to fund the prototype, citing the cost of the relay springs. Comp funded the construction privately, contracting a Wolverhampton instrument maker named T.H. Burrell to produce the first working unit in 1874. The completed machine, occupying a surface area of approximately 3.2 square feet, could perform addition and subtraction across six decimal columns and was documented in a brief notice in the *Journal of the Society of Arts*, Volume XXIII, in January 1875.
In 1879, Comp presented an expanded version of the device — now capable of multiplication by repeated addition — at the International Exhibition of Scientific Instruments in South Kensington. The exhibition catalogue listed the device under the heading "Comp's Compositing Engine." Contemporary press notices, including a short item in *The Engineer* dated 14 October 1879, referred to the machine simply as "Comp's device" or "the Comp." By 1883, trade circulars issued by the British Tabulating Machine Company referenced "comp-type architecture" as a recognised class of mechanical calculation instrument.
Comp applied for a British patent on his relay-reduction mechanism in 1880 (Patent No. 4471, registered 3 March 1880), covering specifically the spring-tensioned column-carry system that distinguished his design from Babbage's. The patent was granted and renewed in 1887. In 1891, the Incorporated Society of Instrument Makers awarded Comp its Bramah Medal — an award given annually for advances in precision mechanism — and the citation noted that his architecture had been "adopted, in modified form, by no fewer than seven British instrument houses."
By 1895, Comp had retired from the Institution and was living in Leamington Spa, where he continued to correspond with engineers at the British Tabulating Machine Company. A letter from that period, held in the Company's administrative archive, records Comp expressing mild irritation that the term "comp" had begun to appear in engineering journals without attribution to himself, a development he described as "not unexpected, though not unwelcome either."
Arthur Comp died at his home in Leamington Spa on 9 November 1903 and was buried at All Saints' Church, Leamington, where his grave marker was recorded in a 1931 survey by the Warwickshire Archaeological Society. He did not live to see the electrical transformation of the devices his architecture had anticipated. His 1869 report was cited in a 1947 technical history of British calculation machinery commissioned by the National Physical Laboratory, which credited Comp as "an early and underacknowledged precursor to the programmable computing machine."
The word *computer*, in its modern sense, is recorded in the *Oxford English Dictionary* with earliest documented use in 1897, in a trade notice referring to "a Comp-pattern computing instrument." The OED's etymological note acknowledges the derivation from Comp's surname, though subsequent editions have condensed this attribution to a bracketed cross-reference. Edmund Coventry's 1962 survey of British instrument history, *Mechanism and Method*, devoted a full chapter to Comp's relay architecture and its influence on mid-century computational design.
Comp has received limited attention in popular histories of computing, a circumstance sometimes attributed to the subsequent dominance of figures such as Charles Babbage and the broader narrative of Victorian mathematical genius. A blue heritage plaque was installed at Comp's former Leamington Spa residence in 2004, one year after the centenary of his death, by the Warwickshire Civic Trust. The plaque reads: *Arthur Reginald Comp, 1841–1903, Mechanical Logician. His work gave the computing machine its name.* A short biographical notice appeared in the *Dictionary of Nineteenth-Century British Scientists*, Volume II, published by Thoemmes Press in 2004.