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　　The Origin of the Refrigerators

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　　By the mid-nineteenth century,

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　　the term icebox had entered the American language,

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　　but ice was still only beginning

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　　to affect the diet of ordinary citizens in the United States.

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　　The ice trade grew with the growth of cities.

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　　Ice was used in hotels, taverns, and hospitals,

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　　and by some forward-looking city dealers in fresh meat,

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　　fresh fish, and butter.

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　　After the Civil War (1861-1865),

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　　as ice was used to refrigerate freight cars,

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　　it also came into household use.

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　　Even before 1880 half of the ice sold in New York,

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　　Philadelphia, and Baltimore,

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　　and one-third of that sold in Boston and Chicago,

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　　went to families for their own use.

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　　This had become possible because a new household convenience,

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　　the icebox, a precursor of the modern refrigerator,

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　　had been invented.

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　　Making an efficient icebox was not as easy as we might now suppose.

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　　In the early nineteenth century,

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　　the knowledge of the physics of heat,

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　　which was essential to a science of refrigeration,

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　　was rudimentary.

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　　The commonsense notion that the best icebox was one

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　　that prevented the ice from melting was of course mistaken,

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　　for it was the melting of the ice that performed the cooling.

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　　Nevertheless,

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　　early efforts to economize ice included wrapping up the ice in blankets,

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　　which kept the ice from doing its job.

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　　Not until near the end of the nineteenth century

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　　did inventors achieve the delicate balance of insulation

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　　and circulation needed for an efficient icebox.

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　　But as early as 1803, an ingenious Maryland farmer,

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　　Thomas Moore, had been on the right track.

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　　When he used an icebox of his own design to transport his butter to market,

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　　his butter, still fresh and hard in neat,

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　　was worth one-pound a brick.

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　　One advantage of his icebox, Moore explained,

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　　was that farmers would no longer have to travel to market at night

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　　in order to keep their produce cool.

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