Page 17 - January 2017
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pendulum. Got it? The patterns are not   Machine—which helpfully included
       entirely random, but can be dictated by   details of the precise settings required
       modifying the various control elements.   for Tisley’s Harmonograph to produce
       Tisley’s Harmonograph operates        each pattern shown in the book. (These
       according to a rational parametric    settings would have been recorded in
       equation, thus:                       the space between the brackets on the St
       (See the image opposite for the       Bride example).























                                  Harmonograph examples
       mathematical formula)                   The purple ink used on this scrap of
         The Harmonograph serves no          paper also showcases a major Victorian
       practical purpose: it was simply a    invention. The Harmonograph pattern is
       Victorian novelty based upon scientifi c   drawn in ink pigmented with the world’s
       principles. It was invented by Hugh   fi rst synthetic dye—aniline purple—
       Blackburn, Professor of Mathematics   probably manufactured in the 1880s just
       at Glasgow University, during the     a few hundred yards from my current
       1840s, although it was Samuel Tisley,   home. Invented by William Perkins in
       in collaboration with his business    1856, it was produced in large quantities
       partner George Spiller, who perfected a   at a factory in Greenford, Middlesex,
       machine to draw these attractive curves   close to the Grand Union Canal.
       according to programmable parameters   Greenford now has a William Perkins
       in the late 1870s. It was possible to   High School, named after the great man.
       reproduce the same pattern again and   The uniform is, perhaps unsurprisingly,
       again by making precise adjustments   a fetching shade of mauve.
       to the mechanisms. In 1893 author H.     Next Month: The Griffi  n Parcels.
       Irwine Whitty demonstrated this in his
       book—The Harmonograph: Illustrated                  Bob Richardson (9718)
       by Designs Actually Drawn by the
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