1960年1月9日——埃及阿斯旺水坝开工。
阿斯旺水坝（Aswan High Dam:位于埃及开罗以南900公里的尼罗河畔.尼罗河美丽的自然景观,舒适的热带气候,丰富的文物古迹和世界上首屈一指的高坝,使阿斯旺的旅游业特别发达.水坝的建设自1960开始，历时10年,耗资9亿美元,站在111米的阿斯旺水坝上,脚下波涛翻滚的世界第一长河尼罗河被拦腰截断,放眼南望是宽15公里长500多公里的纳赛尔湖,这座世界第二大人工湖吞下尼罗河的全年径流,实现河水多年调节,使1964年的洪水,1972年的干旱,1975年的特大洪峰和1982年以来的持续低水位都化险为夷。在几乎全非洲都在闹饥荒的时候，埃及的粮食基本自给自足。
阿斯旺大坝看起来象是铺在大湖上面的一条宽广的公路。大坝两侧除了无边的水面外，还有很多水利设施，这样工业化的场面在埃及是不多见的。
大坝上有水库平面图及说明：弧形拱桥式的大坝，高１１１米，长３８３０米，坝底宽９８０米，顶部宽４０米，动用土石４３００万立方米．将尼罗河拦腰截断，从而使河水向上回流，形成面积达５１２０平方公里、蓄水量达１６４０亿立方米的人工湖-纳赛尔湖。远处是莲花状的大坝建成纪念碑，伴着平静的湖水，我们已无法感受到当年水利工程施工时的浩大场面了。
如果说金字塔和神殿是古代埃及的奇迹，那么阿斯旺水坝就算得上是以科技征服尼罗河的现代奇迹。古代尼罗河每次泛滥，都会对庄园农地造成严重损害，历代君王无不想整治河道，最后终于在19世纪时建了高30.5公尺的水坝，开发出3万8千平方公里的农地，但这仅是全埃及土地的4%。因此在1960年，纳瑟总统在苏联贷款及技术协助下，兴建了高3600公尺长、40公尺高，全世界最大的一座水坝。
现在的阿斯旺水坝所使用的花岗岩，比古夫金字塔用掉的还多，足见其宏伟壮观。目前的12座发电机，不仅可供应埃及的电力，还可提供其它阿拉伯国家使用。因为水坝而建的纳瑟人工湖泊(Lake of Nasser)也相当壮阔，但却严重威胁到岸边的古迹神殿，有不少沉入湖中。联合国教科文组织(UNESCO)为此发动了一连串救援活动，虽然抢救回部分古迹，但仍有非常珍贵的文化遗产惨遭灭顶。
An American astronomer who started out as a student and then a professor of Latin and Greek, but went on to play an important role in establishing the nature of external galaxies. Having earned his Ph.D. in astronomy (1902) from the University of Virginia he joined the staff of the Lick Observatory where he remained until 1920. He then became director of the University of Pittsburgh's Allegheny Observatory and, finally, in 1930, was appointed director of the University of Michigan抯 observatory. Curtis抯 early work involving measuring the radial velocities of stars. In 1910, however, he began investigating spiral nebulae and became convinced that they were independent star systems. In 1917 he argued that the observed brightness of novae, found by him and by George Ritchey on photographs of spiral nebulae, indicated that the nebulae lay well beyond our Galaxy. He also maintained that extremely bright novae, later identified as supernovae, could not be included with the novae as distance indicators. He estimated the Andromeda Nebula (now known as the Andromeda Galaxy) to be 500,000 light-years away, a view opposed by many, including Harlow Shapley who proposed that the Milky Way Galaxy was 300,000 light-years in diameter – far larger than previously assumed – and that the spiral nebulae lay within it. In 1920, at a meeting of the National Academy of Sciences, Curtis engaged in a famous debate with Shapley over the size of the Galaxy and the distance of the spiral nebulae. The matter lay unresolved, however, until 1924 when Edwin Hubble redetermined the distance of the Andromeda Nebula and demonstrated that it was a galaxy in its own right.
发表于 2008-1-9 00:03:38
