On to today:
Several hundred years ago, a band of explorers were embarking on a sea journey to the far north which would last for three weeks. During this time, their staples would consist of crackers and dried meat. They couldn't cook aboard ship for fear of fire. When they arrived, they planned a celebration of roast lamb. The problem they faced was keeping the meat fresh for three weeks. If they tied a rope to the meat and trailed it in the cold water, predator fish would eat it. If they took ice and snow with them to keep the meat cool, the ice and snow would melt and the ship would fill with water. How could they keep the meat fresh until they arrived at their destination?