Your train is chugging along, making good time, when you, the engineer, notice the steam pressure dropping. Without steam, of course, you won’t go far. The fire is still burning well. You should have a full water supply in the tender behind you – then you realize you don’t. And you also know why: Right behind the tender is a circus car, and inside the car is an elephant – no longer thirsty since it has consumed your entire water supply.
This kind of thing has happened before and will happen again on the railroad many call the Leaky Roof. Why the Leaky Roof?