Ice houses were thick-walled structures packed with insulation - often saw dust. Large blocks of ice were cut from frozen lakes and placed in the ice house, packed/separated from one another by sawdust to prevent them from freezing together. The ice lowered the temperature in the ice house and slowed the melting process. If one were lucky, there would be enough ice to last until freezing the following winter. Invariably, there would be a time when there was no ice. Death records often included as the cause of death, "summer sickness" which meant food poisoning from spoilage in the heat.