"A COUNTERWEIGHT on one end, and a cylindrical container on the other end of a steel rope running over two pulleys supported on a pole, makes up the major portion of an ingenious contrivance for cooling foods.
The container, shown in the accompanying photo, fits loosely into a seven-foot hole in the ground lined with a steel casing. It has three shelves, and a door closes it off from the outside. Three iron rods about four feet long run from the top of this "cooler" container to the sustaining end of the rope or cable.
At the point where these rods are connected there is a large circular cover securely fastened. As the cooler is eased downward into the casing in the ground this cover settles over the brim of the casing, and closes it off from the outside. The photograph shows the cover within a few inches of the brim, the cooler being inside the casing.
This cover and the fact that the container is suspended by it several inches above the bottom of the hole, keeps rodents, dirt, and water out of the cooler. The counterweight keeps the device stationary at any level it is moved to." ::Modern Mechanix