First of you need to be a little more specific about your steam engine. The 25-85 in my book is first list in 1915 and also shows up in the 1920 listing. Now here is the catch. There are several styles of the 25-85. Those are all single cylinder engines. Before I looked this up I also found 2 other listings for 25 horsepower N &amp; S engines which are all doubles (2-cylinder). So why don't you tell us a little more what you have. Thanks. J.