By the midnineteenth century, the term “icebox” had entered the American language, but ice was still only beginning to affect the diet of ordinary citizens in the United States. The ice trade grew with the growth of cities. Ice was used in places like hotels and hospitals, and by some forwardlooking city businessmen in fresh meat, fresh fish, and butter. After the Civil War (1861～1865 ), it also came into household use. Even before 1880, half of the ice sold in New York, Philadelphia, and Baltimore, and onethird of that sold in Boston and Chicago, went to families for their own use. This had become possible because a new household convenience, the icebox, early form of the modern refrigerator，had been invented.
Making an efficient icebox was not as easy as we might now suppose. In the early nineteenth century, people only had some simple and basic knowledge of the physics of heat. The common idea that the best icebox was one that prevented the ice from melting was of course mistaken, for it was the melting of the ice that performed the cooling. Early efforts to save ice included wrapping up the ice in blankets, which kept the ice from doing its job. Not until near the end of the nineteenth century did inventors achieve the delicate balance needed for an efficient icebox.
But as early as 1803, a Maryland farmer, Thomas Moore, had been in the correct direction. He owned a farm and used an icebox of his own design for the transportation of his butter to a market in the village of Georgetown. And there he found that customers would pass up the rapidly melting goods of his competitors to pay a higher price for his butter, still fresh and hard in neat, onepound bricks. One advantage of his icebox, Moore explained, was that farmers would no longer have to travel to market at night in order to keep their produce cool.As a result，Moore managed to earn a large sum of money.

The Origin of Refrigerators
History of the icebox	*By the mid19th century the_______ that ice had on American citizens' life was limited mainly to the diet. *When cities grew, the ice ________ increased. *Forwardlooking businessmen used ice to keep meat, fish and butter_______. *After the Civil War, due to the _______ of the modern refrigerator, household use of ice became possible.
Incorrect________ about the icebox	*The icebox ________ best when the ice was prevented from melting. *Ice should be ________ up in blankets to help do its jobs.
Thomas Moore's story	*As early as 1803, Thomas Moore knew how to use an icebox________. *An icebox was designed by Thomas Moore to________ his butter to the market. *Thomas Moore was very______ in his business.