Two 
      years before the publication of Penaud's patent Thomas Moy experimented at 
      the Crystal Palace with a twin-propelled aeroplane, steam driven, which 
      seems to have failed mainly because the internal combustion engine had not 
      yet come to give sufficient power for weight. 
      Moy anchored his machine 
      to a pole running on a prepared circular track; his engine weighed 80 lbs. 
      and, developing only three horse-power, gave him a speed of 12 miles an 
      hour. He himself estimated that the machine would not rise until he could 
      get a speed of 35 miles an hour, and his estimate was correct. 
      Two six-bladed propellers 
      were placed side by side between the two main planes of the machine, which 
      was supported on a triangular wheeled undercarriage and steered by fairly 
      conventional tail planes. 
      Moy realised that he could 
      not get sufficient power to achieve flight, but he went on experimenting 
      in various directions, and left much data concerning his experiments which 
      has not yet been deemed worthy of publication, but which still contains a 
      mass of information that is of practical utility, embodying as it does a 
      vast amount of painstaking work.