Riding his magic carpet made of steam..... Engineer Robert "Bullet Bob" Longo and WW&F #9 appear to be riding a carpet of cottony steam as their freight train drifts downhill off Cockeye Curve with the cylinder cocks open. The cylinder cocks are small valves fore and aft at the bottom of each cylinder. They are typically opened whenever a steam engine has been stationary for some time, or when the train is basically coasting downhill (not under power). Their purpose is to release any liquid water from the cylinders that may have built up from condensing steam. Unlike steam, liquid water is incompressible. If enough of it were to build up within the cylinders, it could result in rupture of the cylinder as the piston basically collides with a wall of fluid that has nowhere to go. So although it produces pretty images, the Engineers aren't doing it for the benefit of the photographers. They are doing it to keep the machinery from tearing itself up.