After the enormous success of the Lehmann engine, another beautiful air engine was invented : the Julius Hock Heissluft-Motors from Wien, Austria.
| Year | Patent Download | Comment | Title | Engine type |
|---|---|---|---|---|
| 1876 | Hock & Martin patent #724 | German patent | Improvements in Hot Air Engines | Open cycle, closed furnace, internal combustion |
| 1877 | Hock & Martin patent #190,490 | Improvements in Hot Air Engines | Open cycle, closed furnace, internal combustion |