30 The origin of Refrigerators
By the mid-nineteenth 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 hotels, taverns, and hospitals, and by some forward-looking city dealers in fresh meat, fresh fish, and butter. After the Civil War,as ice was used to refrigerate freight cars, it also came into household use. Even before 1880,half of 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 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 of insulation and circulation needed for an efficient icebox.
But as early as 1803, and 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, he 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, Moore explained, was that farmers would no longer have to travel to market at night in order to keep their produce cool.
【考研英语高分写作】Part A 历年真题范文
考研英语作文预测及范文(1)
考研英语作文闪光词汇分享
记忆PETS考试英语单词的五大秘诀
【考研英语高分写作】PartA必背范文
【考研英语高分写作】PartA必背范文
PETS二级考试听力理解题型解析
17句搞定考研英语作文
【考研英语高分写作】PartA历年真题范文
2013考研英语写作必背佳句(1)
【考研英语高分写作】PartA历年真题范文
2013年考研英语小作文复习方法和写作技巧
【考研英语高分写作】PartA必背范文
考研写作常用短语须知
2013年考研英语大作文模板
考研英语作文谚语汇总B开头
考研英语写作之环境保护类范文2
考研英语作文预测及范文(4)
【考研英语高分写作】PartA历年真题范文
考研英语写作之环境保护类范文1
考研英语作文预测及范文(2)
考研英语写作常用句型
2013年全国研究生考试考研英语漫画作文预测:网络的利与弊
2012年公共英语三级阅读理解辅导
考研英语作文预测及范文(6)
2013年考研英语大作文模板
考研英语作文靓词替换高分策略
公共英语三级PETS3作文经典辅导
如何在有限时间里写好考研英语作文
2013年考研英语小作文复习方法和写作技巧
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |