Of course, in this case Twain is guilty of statistics. The group of people most likely to die (old, infirm, sick) are more likely to be in a bed than on a train. And the people in New York beds spend a significant fraction of the year there, while the people on the train are only there for only a few hours or days. If Twain made an honest comparison of deaths per hour across similar demographic groups, the bed would look a lot better than the train.