Percy Ludgate
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Percy Edwin Ludgate (2 August 1883 – 16 October 1922) was an Irish amateur scientist who designed the second analytical engine (general-purpose
Turing-complete In computability theory, a system of data-manipulation rules (such as a model of computation, a computer's instruction set, a programming language, or a cellular automaton) is said to be Turing-complete or computationally universal if it can be ...
computer) in history.


Life

Ludgate was born on 2 August 1883 in
Skibbereen Skibbereen (; ) is a town in County Cork, Ireland. It is located in West Cork on the N71 national secondary road. The River Ilen runs through the town; it reaches the sea about 12 kilometres away, at the seaside village of Baltimore. Located ...
,
County Cork County Cork () is the largest and the southernmost Counties of Ireland, county of Republic of Ireland, Ireland, named after the city of Cork (city), Cork, the state's second-largest city. It is in the Provinces of Ireland, province of Munster ...
, to Michael Ludgate and Mary McMahon. In the 1901 census, he is listed as
Civil Servant The civil service is a collective term for a sector of government composed mainly of career civil service personnel hired rather than elected, whose institutional tenure typically survives transitions of political leadership. A civil service offic ...
National Education (Boy Copyist) in
Dublin Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, pa ...
. In the 1911 census, he is also in Dublin, as a Commercial Clerk (Corn Merchant). He studied accountancy at Rathmines College of Commerce, earning a gold medal based on the results of his final examinations in 1917. At some date before or after then, he joined Kevans & Son, accountants.


Work on analytical engine

It seems that Ludgate worked as a clerk for an unknown corn merchant, in Dublin, and pursued his interest in calculating machines at night.
Charles Babbage Charles Babbage (; 26 December 1791 â€“ 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer. Babbage is considered ...
in 1843 and Ludgate in 1909 designed the only two mechanical analytical engines before the electromechanical analytical engine of
Leonardo Torres Quevedo Leonardo Torres Quevedo (; 28 December 1852 – 18 December 1936) was a Spanish civil engineer, mathematician and inventor, known for his numerous engineering innovations, including Aerial tramway, aerial trams, airships, catamarans, and remote ...
of 1920 and its few successors, and the six first-generation electronic analytical engines of 1949. Working alone, Ludgate designed an analytical engine while unaware of Babbage's designs, although he later went on to write about Babbage's machine. Ludgate's engine used multiplication as its base mechanism (unlike Babbage's which used addition). It incorporated the first multiplier-accumulator, and was the first to exploit a multiplier-accumulator to perform division, using multiplication seeded by reciprocal, via the convergent series . Ludgate's engine also used a mechanism similar to slide rules, but employing unique, discrete "Logarithmic Indexes" (now known as Irish logarithms), as well as a novel memory system utilizing concentric cylinders, storing numbers as displacements of rods in shuttles. His design featured several other novel features, including for program control (e.g., preemption and
subroutine In computer programming, a function (also procedure, method, subroutine, routine, or subprogram) is a callable unit of software logic that has a well-defined interface and behavior and can be invoked multiple times. Callable units provide a ...
s – or
microcode In processor design, microcode serves as an intermediary layer situated between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. It consists of a set of hardware-level instructions ...
, depending on one's viewpoint). The design is so dissimilar from Babbage's that it can be considered a second, unique type of analytical engine, which thus preceded the third (
electromechanical Electromechanics combine processes and procedures drawn from electrical engineering and mechanical engineering. Electromechanics focus on the interaction of electrical and mechanical systems as a whole and how the two systems interact with each ...
) and fourth ( electronic) types. The engine's precise mechanism is unknown, as the only written accounts which survive do not detail its workings, although he stated in 1914 that " mplete descriptive drawings of the machine exist, as well as a description in manuscript" – these have never been found. Ludgate was one of just a few independent workers in the field of science and mathematics. His inventions were worked on outside a lab. He worked on them only part-time, often until the early hours of the morning. Many publications refer to him as an accountant, but that came only after his 1909 analytical engine paper. Little is known about his personal life, as his only known records are his scientific writings. Prior to 2016, the best source of information about Ludgate and his significance was in the work of Professor
Brian Randell Brian Randell (born 1936) is a British computer scientist, and emeritus professor at the School of Computing, Newcastle University, United Kingdom. He specialises in research into software fault tolerance and dependability, and is a noted ...
. Since then, further investigation is underway at
Trinity College, Dublin Trinity College Dublin (), officially titled The College of the Holy and Undivided Trinity of Queen Elizabeth near Dublin, and legally incorporated as Trinity College, the University of Dublin (TCD), is the sole constituent college of the Univ ...
under the auspices of the John Gabriel Byrne Computer Science Collection. Ludgate died of
pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...
on 19 October 1922, and is buried in Mount Jerome Cemetery in Dublin.


Legacy

In 1960, a German patent lawyer working on behalf of
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
successfully relied on Ludgate’s 1909 paper to defeat an important 1941 patent application by the pioneering computer scientist
Konrad Zuse Konrad Ernst Otto Zuse (; ; 22 June 1910 – 18 December 1995) was a German civil engineer, List of pioneers in computer science, pioneering computer scientist, inventor and businessman. His greatest achievement was the world's first programm ...
. Had the patent been approved, Zuse would have controlled the primary intellectual property for crucial techniques that all computers now use; this would have changed his career and could well have altered the commercial trajectory of the computer industry. In 1991, a prize for the best final-year project in the Moderatorship in
computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...
course at
Trinity College, Dublin Trinity College Dublin (), officially titled The College of the Holy and Undivided Trinity of Queen Elizabeth near Dublin, and legally incorporated as Trinity College, the University of Dublin (TCD), is the sole constituent college of the Univ ...
– the Ludgate Prize – was instituted in his honour, and in 2016 the Ludgate Hub e-business incubation centre was opened in
Skibbereen Skibbereen (; ) is a town in County Cork, Ireland. It is located in West Cork on the N71 national secondary road. The River Ilen runs through the town; it reaches the sea about 12 kilometres away, at the seaside village of Baltimore. Located ...
, where he was born. In October 2022, a plaque from the National Committee for Commemorative Plaques in Science and Technology was unveiled at Ludgate's home in Drumcondra by the Provost of Trinity College, Linda Doyle. (As can be seen in the photo, the year of birth is listed incorrectly on the plaque.) Also in 2022, a podcast with Dr Chris Horn discussed Percy Ludgate, then in October 2024 an appealing and accurate podcast on Percy Ludgate was created by Google's Gemini A.I..


References


Bibliography

* Available on-line at:
Fano.co.UK
* * (A subscription to the journal or payment on a per-article basis is required to view this article) â€
full version
* * * (extensive background and research document), and . In: online catalog of The John Gabriel Byrne Computer Science Collection * Brian Coghlan (2019) "An exploration of the life of Percy Ludgate": and , presented at the West Cork History Festival 2019, Skibbereen, Ireland * (see als

* (see als

* online catalog * Mobile-friendly Ludgate folder of the above catalog * (see Book Depositor

also see BookFinde

* * {{DEFAULTSORT:Ludgate, Percy 1883 births 1922 deaths People from Skibbereen 20th-century Irish businesspeople 20th-century Irish scientists Irish inventors Businesspeople from Dublin (city) Scientists from Dublin (city) Computer designers Deaths from pneumonia in the Republic of Ireland Burials at Mount Jerome Cemetery and Crematorium