Percy Ludgate
Percy Edwin Ludgate (August 2, 1883 – October 16, 1922) was an accountant in Dublin and designer of an Analytical Engine.
Percy Ludgate was born in Skibbereen Co. Cork and studied at Rathmines College of Commerce, where he was a gold medal student, before joining a Dublin firm of accountants. From 1903 he spent his spare time designing his analytical machine, presenting the details to the Royal Dublin Society in 1909. This brought him to international attention and in 1914 the Royal Society invited him to lecture in Edinburgh at a special conference on mathematics and computing.
Possibly the first portable computer — more “table top” than “laptop” — was designed around 1907 by an inventive Irish accountant, Percy Ludgate. His invention gets a place in the history of computing, although it was never built.
Percy Ludgate, accountant by day, computer designer by night. Since the invention of the abacus, people have been trying to build more complex calculating machines. Charles Babbage (1791-1871), the ‘grandfather of computing’, spent years and a fortune designing his programmable calculating machines. His ideas were based on the Jacquard loom, where punched cards controlled the patterns. But his machines were impossible to build and only small sections were ever attempted. And even these were enormous, ponderously slow – everything was reduced to addition or subtraction – and required thousands of precision-engineered metal parts.
Percy Ludgate’s design was also based on the Jacquard loom, but was different in most other respects from Babbage’s machine, and when Ludgate started on his ideas, he initially knew nothing of Babbage. Where Babbage used columns of toothed discs to store numbers, for example, Ludgate (1883-1922) opted for a simpler shuttle mechanism.
Ludgate’s ‘analytical machine’ was programmable, yet small enough to be portable, and it had all the elements of a modern computer: a mechanism for storing data, ways to input data and program the machine (using pre-punched ‘formula’ tape and/or keyboards), a printer and even an ‘operating system’, all of which Ludgate designed himself. (More details: article from The Computer Journal, 1971)
Uniquely, Ludgate’s mechanical computer had two innovative features: it could be stopped at any stage in a calculation to add new variables, and it could do subroutines. (Ludgate’s approach to calculations was also unusual: for multiplication he developed a technique using partial products; for division he used a table of reciprocals and a rapidly converging series using subroutines.)
He calculated that his engine would multiply two 20-digit numbers in under ten seconds, and take two minutes to determine the logarithm of a number. It could also be set to solve algebraic equations and geometric problems. Ludgate envisaged it would be powered by an electrical motor, and the calculations automated, and the complete device, measuring about two feet in every direction, would be portable.
Working alone, Ludgate designed an Analytical Engine while unaware of Charles 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, Ludgate's engine used rods similar to slide rules. Its precise mechanism is unknown as the only written accounts of the engine which survive do not detail its workings.
Ludgate also helped advance calculators by expanding Charles Babbage's design for the first programmable computer. He was one of a few independent workers in the field of science and mathematics. His inventions were worked on outside a lab. He worked on the inventions only part-time.
His design featured several novelties, including a method of implementing multiplication referred to at the time as "Irish logarithms". (Boys, 1904) Sadly, the machine was probably never made. During World War I Ludgate was diverted to work on a committee organising the supply of oats for the British cavalry, and he seems not to have returned to his computer.
Little is known about Ludgate's life, as his only records are his scientific writings. The best source of information about Ludgate and his significance lie in the work of Professor Brian Randell.
He died of pneumonia aged 39, after returning from a Swiss walking holiday. In 1991 the British Museum made the first complete Babbage difference engine. Sadly, little of Percy Ludgate’s design survives, so we will probably never see a working model of this pioneering Irish calculating engine.
In 1991, a prize for the best final year project in the Moderatorship in computer science course at Trinity College Dublin – the Ludgate Prize – was instituted in his honor.
In 2015, a group of established business people set up a non-profit company in the name of Ludgate in Skibbereen, Co. Cork, with the aim of developing the local economy through the medium of digital technology and local innovation.
References
- C. V. Boys (July 1909). "A new analytical engine". Nature 81 (2070): 14–15. doi:10.1038/081014a0.
- Ludgate, Percy E. (April 1909). "On a proposed analytical machine". Scientific Proceedings of the Royal Dublin Society 12 (9): 77–91. Available on-line at: Fano.co.UK
- Ludgate, P. E. (1914). "Automatic calculating machines". In Ellice Martin Horsburgh. Napier tercentenary celebration: Handbook of the exhibition of Napier relics and of books, instruments, and devices for facilitating calculation. Royal Society of Edinburgh. pp. 124–127.
- Brian Randell (1971). "Ludgate's analytical machine of 1909". The Computer Journal 14 (3): 317–326. doi:10.1093/comjnl/14.3.317. (A subscription to the journal or payment on a per-article basis is required to view this article)
- Brian Randell (1982). "From analytical engine to electronic digital computer: The contributions of Ludgate, Torres, and Bush" (PDF). IEEE Annals of the History of Computing 4 (4): 327–341. doi:10.1109/MAHC.1982.10042.
- "The Feasibility of Ludgate's Analytical Machine".