Here's another beautiful 19th Century steam engine, the Pennsylvania RR's Ely's No.10. As a prototype for a new express engine sporting large drive wheels (those two big wheels towards the rear of the engine) higher speeds were possible. But this wasn't the only experiment with large drive wheels. Both here and in Europe, engines with only two very large wheels (unlike the four drive wheels on the No. 10), were tried with mixed results. The larger wheels allowed for greater speed but overall had poor traction and weren't good for pulling freight trains. Enjoy!
