What does the S symbol on the front of the chimney in many older houses represent?

Believe this or not but the Big "S" on the side of chimneys in the old days had two short iron hooks on either end of the Big "S" and that's how the Chimney Flue was opened and closed. The home owner had a long wood pole that would attach to the Iron Peg on the Big "S" and the home owner would push it up to Open the Flue or pull in down 1/2 way to closed the flue. Of course the home owner could adjust the Flue to any stage they would like in between the fully open position, or the fully closed position. Later on instead of having to go outside to adjust the Flue they came up of a way to install the flue adjustment just above the fire box; however, down through the years the Big "S" Iron Flue Adjustment on chimneys became just an attractive symbol that builders are still attaching to chimneys today.