Introduction Typical Harper Cast Fence Post John Harper left his parents’ farm near Turriff in Aberdeenshire around the age of 9 and found employment as a market gardener before moving down to Edinburgh with his brother Hugh, where they became wire fencers. This continued in Glasgow and in 1856 they returned to Aberdeen to set up their own business as fencers and gate manufacturers. Before long they had established a foundry. In 1863, aged 30, John Harper registered a patent ‘device for straining wire’, which was crucial to the development of bridge building. Illustrated is a corner fence post from the Speyside line. This post has within it four wire tensioning devices visible, each able to rotate round the axis at right angles to the wire that passes through the outer casing, to be wound onto the rotating spindle. The wire was wound up within the post using a tool rather like an ‘Allen’ key. Once the desired tension was generated, the spindle was locked by the insertion of a peg into the opposing notches, one on the spindle and the other on the casing. This was similar to the ‘key’ required to fix a wheel to its axle after the creation of slots in both components – a technique central to Harpers main business of supplying power drive machinery to Aberdeen’s paper industry. It is interesting that the notches on the spindle are at 90 degree intervals while those on the casing are at 60 degree intervals. This means that a rotation of only 30 degrees will allow another opposing pair to accept the locking key or peg. more... |
Introduction
Louis Harper, Designer Other Bridges Aboyne, 1871 Shocklach,Cheshire, 1871 Monymusk, 1879 Burnhervie, c.1880 Birkhall, 1880 Cromdale, 1881 Nairn, 1887 Crathorne, c.1888 GNR at Offord & Lincoln, c.1890 Bandon, Eire 1890 Polhollick, 1892 Larbert, 1893 Trentham, 1893 Feugh, 1893 Baroda, India c.1893 Grimsby, 1894 Sellack Boat, 1895 Jumna, India 1895 Blairgowrie, 1896 Doveridge, Derbyshire, 1898 Keswick, 1898 Taff Valley, c.1898 Tsomo, South Africa 1898 Narva, Estonia c.1898 Newquay, 1900 Patan, Nepal c.1900 Tursoli, Nepal, 1900 Aberlour, 1902 Chobar Gorge, Nepal 1903 Cambus 'o May, 1905 Ballochbuie, 1924 Other Links |
