Henry Essex patented his design in 1902 (US patent 723,660) the engines were built by W. H. Smith of Buffalo, in the state of New York.
A number of engines were built to Essex's designs :

1. The single cylinder engine, type 1 (see also Buffalo toy engine) and double cylinder type 2 model engine.

   
   (above) single cylinder type 1
   
   (above) Double cylinder type 2 engine dissasembled
   
   (above) side view.
   

2. The type F power unit, with water cooling, for use in washing machines
   
3. The type E ventilating fan
   
   
4. The type D ventilating fan
   
   (above) Type D fan, 1912 price sheet.