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[quote user="MichaelSol"][quote user="Bucyrus"][ If you are comparing the actual performance of the two locomotives in the tables, it seems unfair that they are not matched in horsepower, size, or similar indicator.[/quote]If you compare two gasoline engines and measure the hp of one at 4000 rpm and another at 6000 rpm, you don't really have much of a comparison, and the test would meet no ISO or ASTM standard of testing that I am aware of. Or, the hp of one at 4,000 rpm and the other at some other speed where it finally maxes out on the dynamometer. Are the machines "comparable"? Well, you might as well call it a random test -- you found two machines that perform differently; basically here you want to compare a small steam engine and a large Diesel-electric. Well, why not take a large Steam engine and compare it to a small Diesel-electric then? The little DE might well generate, at 19 mph, the hp of the Steam engine at 4 mph. If you set those as your metrics, you could "prove" that a Diesel-electric was more powerful that a large Steam engine. But that's false, you only prove that it is different under different metrics. It's not a comparison that shows anything useful, but that's what you are doing -- trying to compare machines by scrambling the "comparisons" so that they are not comparable at all.Well, that's the game in cherry picking differing metrics. Somewhere in between, there is a useful measure and that is either locomotives rated similarly at similar speeds, or with similar weight on drivers. "Comparable" machines are selected based on comparable metrics -- but they have to be comparable at some particular point of commonality, because only then can you compare their performance across a range.  [/quote]I think I understand what you are saying about the comparison.  At first I was taken aback when you said that I want to compare a small steam engine to a larger diesel-electric.  My intent was to compare equal locomotives for a fair comparison, and I assumed that equal horsepower rating would be sound criteria for determining equality between the two locomotives.  To me, it seemed that what you were doing is comparing a larger steamer to a small diesel because your steamer has a considerably higher hp rating than your diesel.  But if I understand you now, you contend that a fair comparison would be between a steamer and a diesel of similar or identical weight.  And inherent with these two equal weight locomotives, the steamer would have a higher horsepower rating and can produce higher tractive effort than the diesel.  I see no problem with that criterion for a fair comparison.  I guess that ultimately the decision of which motive power is preferable depends on how much work it does over its life cycle and at what cost.
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