The story of patents holding up steam is a myth, one that I believe was more recently spread by Boldrin & Levine's "Against Intellectual Monopoly" book. Here is

The story of patents holding up steam is a myth, one that I believe was more recently spread by Boldrin & Levine's "Against Intellectual Monopoly" book. Here is a paper comprehensively busting that myth: http://terry.uga.edu/~jlturner/StrongSteamApril2009.pdf http://terry.uga.edu/~jlturner/StrongSteamApril2009.pdf. TLDR: Steam did take off after Watt's patents expired, but there is no causality because his patents claimed the condenser, which works in the exact opposite manner as the "expansive" use of high pressure steam. High-pressure steam languished initially because it was extremely risky. Ironically, Watt's patents probably encouraged work on high pressure steam because his rivals wanted to work around them. However, it is a really well-written paper that provides fascinating insight into the technological atmosphere of that era, and I highly recommend reading it. BTW, here's another paper from the same authors calling out Boldrin & Levine for further fabricating history when the above paper was bought to their attention: http://terry.uga.edu/~jlturner/WattAgainAug2009.pdf http://terry.uga.edu/~jlturner/WattAgainAug2009.pdf