In 1850 Rudolph Clausius obtained the conclusion "All heat engines working between the same two temperatures have the same maximal efficiency": http://web.lemoyne.edu/~giunta/Clausius.html http://www.mdpi.org/lin/clausius/clausius.htm Clausius was forced to use an invalid argument for reasons described here: http://www.wbabin.net/valev/valev4.htm Eventually Clausius conclusion took

In 1850 Rudolph Clausius obtained the conclusion "All heat engines working between the same two temperatures have the same maximal efficiency": http://web.lemoyne.edu/~giunta/Clausius.html http://www.mdpi.org/lin/clausius/clausius.htm Clausius was forced to use an invalid argument for reasons described here: http://www.wbabin.net/valev/valev4.htm Eventually Clausius conclusion took