How Does A Thermador Swamp Cooler Work?

My calendar today has a picture of an old VW Bug with a big cylinder hanging out of its passenger side window. I knew it was for ventilation but didn't really know how it worked. So I did a little research.

It's a Thermador Swamp Cooler. The unit is attached to the window. Inside is a blanket with a string attached. The string runs into the passenger compartment. The tube is almost half filled with cold water. As one drives, air goes into the tube, through the wet blanket, and into the car as cold air. The string is used to rotate the blanket and dampen it.