Charles Babbage (1845). Oil on canvas. 127 x 102. Charles Babbage was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer. Considered by some to be a father of the computer, Babbage is credited with inventing the first mechanical computer that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in Babbage's Analytical Engine. His varied work in other fields has led him to be described as pre-eminent among the many polymaths of his century. Parts of Babbage's incomplete mechanisms are on display in the Science Museum in London. In 1991, a functioning difference engine was constructed from Babbage's original plans. Built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbage's machine would have worked. Babbage's birthplace is disputed, but according to the Oxford Dictionary of National Biography he was most likely born at 44 Crosby Row, Walworth Road, London, England. A blue plaque on the junction of Larcom Street and Walworth Road commemorates the event. His date of birth was given in his obituary in The Times as 26 December 1792; but then a nephew wrote to say that Babbage was born one year earlier, in 1791. The parish register of St. Mary's, Newington, London, shows that Babbage was baptised on 6 January 1792, supporting a birth year of 1791. Babbage was one of four children of Benjamin Babbage and Betsy Plumleigh Teape. His father was a banking partner of William Praed in founding Praed's & Co. of Fleet Street, London, in 1801. In 1808, the Babbage family moved into the old Rowdens house in East Teignmouth. Around the age of eight, Babbage was sent to a country school in Alphington near Exeter to recover from a life-threatening fever. For a short time he attended King Edward VI Grammar School in Totnes, South Devon, but his health forced him back to private tutors for a time. Babbage then joined the 30-student Holmwood Academy, in Baker Street, Enfield, Middlesex, under the Reverend Stephen Freeman. The academy had a library that prompted Babbage's love of mathematics. He studied with two more private tutors after leaving the academy. The first was a clergyman near Cambridge; through him Babbage encountered Charles Simeon and his evangelical followers, but the tuition was not what he needed. He was brought home, to study at the Totnes school: this was at age 16 or 17. The second was an Oxford tutor, under whom Babbage reached a level in Classics sufficient to be accepted by Cambridge. Babbage arrived at Trinity College, Cambridge, in October 1810. He was already self-taught in some parts of contemporary mathematics; he had read in Robert Woodhouse, Joseph Louis Lagrange, and Marie Agnesi. As a result, he was disappointed in the standard mathematical instruction available at the university. Babbage, John Herschel, George Peacock, and several other friends formed the Analytical Society in 1812; they were also close to Edward Ryan. As a student, Babbage was also a member of other societies such as The Ghost Club, concerned with investigating supernatural phenomena, and the Extractors Club, dedicated to liberating its members from the madhouse, should any be committed to one. In 1812 Babbage transferred to Peterhouse, Cambridge. He was the top mathematician there, but did not graduate with honours. He instead received a degree without examination in 1814. He had defended a thesis that was considered blasphemous in the preliminary public disputation; but it is not known whether this fact is related to his not sitting the examination. Considering his reputation, Babbage quickly made progress. He lectured to the Royal Institution on astronomy in 1815, and was elected a Fellow of the Royal Society in 1816. After graduation, on the other hand, he applied for positions unsuccessfully, and had little in the way of career. In 1816 he was a candidate for a teaching job at Haileybury College; he had recommendations from James Ivory and John Playfair, but lost out to Henry Walter. In 1819, Babbage and Herschel visited Paris and the Society of Arcueil, meeting leading French mathematicians and physicists. That year Babbage applied to be professor at the University of Edinburgh, with the recommendation of Pierre Simon Laplace; the post went to William Wallace. With Herschel, Babbage worked on the electrodynamics of Arago's rotations, publishing in 1825. Their explanations were only transitional, being picked up and broadened by Michael Faraday.