1865), as ice used to refrigerate freight cars, it also came into household use. Even before 1880,
half the ice sold in New York, Philadelphia, and Baltimore, and one-third 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, a precursor 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, the knowledge of the physics of heat , which was essential to a science of
refrigeration, was rudimentary. The commonsense notion 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. Nevertheless, early efforts to economize ice included wrapping the ice
blankets, which kept the ice from doing its job. Not until near the end of the nineteenth century
did inventors achieve the delicate balance of insulation and circulation needed for an efficient
icebox.
But as early as 1803, an ingenious Maryland farmer, Thomas Moore, had been on the right
track. He owned a farm about twenty miles outside the city of Washington, for which the village
of Georgetown was the market center. When he used an icebox of his own design to transport his
butter to market, hr found that customers would pass up the rapidly melting stuff in the tubs of his
competitors to pay a premium price for his butter, still fresh and hard in neat, one-pound bricks.
One advantage of his icebox, more explained, was that farmers would no longer have to travel to
market at night in order to keep their produce cool.
Bạn đang xem 1865) - Đề thi thử Đại học lần 4 môn Anh khối A1, D năm 2014 - Cô Vũ Thu Phương