New England is home to many railroad “firsts,” but none is more impressive than the Mount Washington Cog Railway, the world’s first cog rail line. And it’s still running, at a profit, 152 years late, using some of the original equipment. Unlike most railroads, “The Cog” doesn’t pull its coaches along a relatively flat line with flanged wheels on two parallel tracks. A cog railroad’s locomotive directly connects its gears to a center rack of iron teeth, pushing the train up the mountain very slowly, but surely. On a normal railroad the train can handle a 2% grade (or climb) at best.