wrote on Jul 15^th, 2007 at 4:03pm:

I belive sawdust was originaly used back in the days when people used ice boxes to keep food cold. The only way they could keep the ice from melting in summer was to put it under sawdust.

L.T.sully is right.  My dad talks about an ice house they had.  In the winter they would cut large chunks of ice out of the lake and layer them  in the ice house.  In between the layers a good amount of saw dust.

My dad claims they would have ice well into July, amazing.