The Collaborative International Dictionary of English v.0.48:

Tromp \Tromp\, n. [F. trombe, trompe, a waterspout, a
   water-blowing machine. Cf. Trump a trumpet.]
   A blowing apparatus, in which air, drawn into the upper part
   of a vertical tube through side holes by a stream of water
   within, is carried down with the water into a box or chamber
   below which it is led to a furnace. [Written also trompe,
   and trombe.]
   [1913 Webster] Tromp