PROBLEM OF PROPELLOR HAS ARCHITECTS UP A PEDIMENT

It's got them stumped up at the Architectural School. They say that Gropius can't understand it. It's a notched hard wood stick, with a nail stuck in the end and on the nail a propellor. You hold the stick in either hand and with the other rub a second stick, any shape, across the notches.

Round and round goes the propellor. When a finger of the rubbing hand is in one position, the propellor goes one way, when in another, the other.

Almost everybody has seen it. In a few days they are going to call in the Physics Department and ask for an explanation.