A Summary of Patents, Achievements, Commissions and Awards of E J Dent & Co
1790
Birth of Edward John Dent, founder of the firm.
1800
Aged 10, Dent acquires his first watch — an Earnshaw chronometer. He would always use an Earnshaw type of detent in his own creations.
1814
Constructs the Standard Astronomical Clock for the Admiralty. Produces chronometers for determining longitude for the Colonial Office African Expedition.
1815–1829
Trains under Richard Rippon, works for Vulliamy & Son, and assists with repeaters and chronometer work at Barraud & Son.
1829
Dent No.114 awarded First Premium by the Astronomer Royal after trial: variation of just 0.54 hundredths of a second per year.
1830
Forms Arnold & Dent partnership with John Roger Arnold.
1831
Chronometer No. 633 sails aboard HMS Beagle with Charles Darwin.
1833–1834
Discovers properties of balance springs made of different metals. Researches magnetism’s effect on chronometers. Invents glass balance springs.
1836
Obtains patents for improvements in balance springs and their adjustment.
1837–1839
Determines longitude differences between Greenwich and Paris, Armagh, Edinburgh, and New York with chronometers.
1840
Arnold partnership ends. Produces under his own name again. Patents pendulum impulse and balance spring improvements.
1842–1843
Constructs standard clocks for Turin and Geneva. Appointed Chronometer Maker to the Emperor of Russia. Supplies 81 chronometers for a Russian Government expedition. Registers patents for compasses and meridian instruments.
1845
Constructs the Great Clock of the Royal Exchange, praised as the best in the world by the Astronomer Royal.
1846–1849
Patents “The Keyless” (1846). Constructs the Standard Astronomical Clock at Pulkova (1847). Invents electro-magnetic clocks (1848). Builds Venice Observatory clock (1849).
1850
Explorer David Livingstone purchases Dent Chronometer No.1800 for his African expeditions.
1851
Turret clock at the Great Exhibition wins Council Medal; later installed at King’s Cross Station. Wins medal for Patent Ships’ & Surveying Compasses. Invents Prism Chronometer Balance. Patents the Single Pin Escapement.
1852–1853
Awarded the contract for the Great Clock of Westminster. Edward John Dent dies in 1853; Frederick Dent carries the project forward.
1859
The Great Clock of Westminster, Big Ben, is installed and enters service.
1862
Patents the “Watchman’s Tell Tale Clock”. Constructs Great Clock at the International Exhibition. Wins awards for chronometers, watches, clocks, and compasses. Invents Double Bar Auxiliary Chronometer Balance.
1863–1869
Establishes telegraphic time communication with Greenwich and Big Ben (1863). Invents fog bell machinery for lighthouses (1865). Builds Ordnance Survey standard clock (1868). Patents Improved Tail Lever Escapement (1869).
1870
Constructs “First Class” standard astronomical clocks for the Transit of Venus expeditions.
1871
Constructs the Standard Clock of the Royal Observatory, Greenwich — the regulator that defined GMT across the Empire.
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