Book 26, Question 59
How did people keep food cold before refrigerators?
In cold places, workers cut big blocks of ice from frozen lakes in winter and stored them in sheds packed with sawdust.
In summer the ice was delivered to homes and put into insulated iceboxes. Machines that move heat out of a box, the way modern fridges do, appeared in the 1800s. Electric home refrigerators became common in the 1930s.