Low and medium temperature thermal Pyridostatin is available from many renewable energy sources. The cost effective conversion of thermal into mechanical energy however still poses an engineering problem. One solution for thermal energy with temperatures of 100–150 °C could be the atmospheric steam engine. Its theory was recently revisited in order to increase the machine's efficiency. The improved theory indicates that the addition of a forced expansion stroke can increase the theoretical efficiencies from 6.5 to 20%. At Southampton University, a series of fundamental model tests was conducted in order to assess these predictions. The following conclusions were drawn.1.The theoretically postulated atmospheric cycle with forced expansion of steam is possible.2.Air leakage through the seals limited the performance of the experimental machine.3.The efficiency without expansion reached 3.2% with a condensation pressure of 46 kPa (abs.).4.Efficiencies with forced expansion ranged from 4.1% for an expansion ratio of 1.33:1–10.2% for an expansion ratio of 4:1.5.The theoretical maximum efficiency of the simple atmospheric cycle of 3.6% was exceeded by a factor of 2.8%.