LETTERS : Safe Schilling

From Mr Simon Walker Sir: In his article on Rolls Royce ("A bulldog bred in Bavaria", 20 December), Jonathan Glancey notes correctly that the Merlin engines fitted to Battle of Britain-period Spitfires had a disconcerting tendency to run out of fuel during high-speed or inve rted manoeuvres. I believe that a solution to this problem was found in the quaintly named "Miss Shilling's (or Schilling's) orifice" - a metal disc the size of an old ha'penny with a hole drilled through it that acted as a non-return valve to prevent fu el from running back through the carburettors in such circumstances. High-technology it may not have been but at least it levelled the playing field.

Yours sincerely, SIMON WALKER Oxford 20 December