the 1970s. Girling brakes have the quirk of using natural rubber (later nitrile) seals. Girling still manufacture disc brakes in Birmingham today. 1902: George Andrew Darby patents the first electrical heat detector and smoke detector. 1903: Birmingham-born patent lawyer Bertram Hopkinson is elected to the Cambridge chair in mechanism and applied mechanics, where he carries out early research on tank armour plating. Hopkinson builds a team of researchers, one of whom is Harry Ricardo, the engineer who makes his name for his pioneering work on internal combustion engines. Hopkinson encourages Ricardo to work on engines. 1903: Brummie Francis William Aston wins a scholarship to the University of Birmingham and in his studies of electronic discharge tubes he discovers the phenomenon now known as the Aston Dark Space. He later moves to the Cavendish Laboratory in Cambridge, where he uses a method of electromagnetic focusing to invent the mass spectrograph, which rapidly allows him to identify no fewer than 212 of the 287 naturally occurring isotopes. His work on isotopes also leads to his formulation of the Whole Number Rule, which is later used extensively in the development of nuclear energy. In 1922 he wins the Nobel Prize in Chemistry for the invention of the mass spectrometer. 1905: A manually powered domestic vacuum cleaner is invented by manufacturer Walter Griffiths of 72, Conybere Street, Highgate. It is originally patented as 'Griffiths' Improved Vacuum Apparatus for Removing Dust from Carpets'. Although an electric cleaner is patented in 1901 by H. Cecil Booth, Griffiths' design is more similar to modern portable cleaners than Booth's cart-mounted device. 1905: Herbert Austin begins making cars at Longbridge, many improvements in mass car manufacture and production later arise from these car works. Seventeen years later the Austin 7 goes into production, it becomes one of the most popular cars ever produced for the British market, its effect on the British market is similar to that of the Model T Ford in the USA. Austin's designs and production help set up other car brands around the world that later become famous in their own right, such as BMW, Nissan and Lotus. 1905: Accles & Pollock Produces the first tubular box spanners. 1906: The earliest work on the parkerizing processes is developed by British inventors William Alexander Ross, in 1869, and by Thomas Watts Coslett, in 1906. Coslett, of Birmingham, subsequently files a patent based on this same process