历史回眸
电报发明人马柯尼诞辰 美苏军队易北河会师
美国女学生访问前苏联 哈勃望远镜安全上轨
参考文本
- April 25th, 1874, Radio (1)pioneer Guglielmo Marconi is born in Bologna, Italy. "In spite of the great distance bodily separating us, you hear my voice as clearly and (2)distinctly as I think you should."
- 1945, During World War II, U.S. and Soviet (3)troops meet on the Elbe River in Central Europe, it's a sign that the (4)collapse of Nazi Germany and the end of the war in Europe are near.
- 1983, Soviet leader Yuri Andropov invites Maine (5)schoolgirl Samantha Smith to visit the USSR. Smith who had sent Andropov a letter expressing her (6)fears about the nuclear war makes that visit a few months later.
- And 1990, "Ah, the Discovery now backing away from the Hubble Space Telescope, the first of NASA's great (7)observatories is now on station at 330 (8)nautical miles above the earth." The space shuttle "Discovery" (9)deploys the Hubble Space Telescope into (10)orbit around the earth.
Today In History, April 25th, Mike Gracia, the Associated Press.
重点分析
- Guglielmo Marconi：电报发明者、无线电技术先驱马柯尼
在电报的发明专利问题上，一直存在争议，事实上在马柯尼之前，Tesla就在美国申请了相关的专利。不过由于商业上的成功，美国专利局将这一专利改授给马柯尼，他也因发明电报获得诺贝尔奖。二战以后，同样可能处于商业利益考虑，美国最高法院在Tesla死后追认了他的专利。据说是因此可以免去马柯尼公司对二战损失的索赔。
马柯尼在英国建立的通讯公司在1920年进行了第一次实验性的无线电广播，从此电台广播进入了人们的生活。 - USSR：苏联，Union of Soviet Socialist Republics
简称为Soviet Union，or Russia - nautical miles：海哩
nautical指海的，与海有关的。
海里，可简作nm,nmi,NM，这一单位常用于航海和航天。它本来指的是地球大圆上一分弧对应的长度，因为是与角度对应的度量单位，所以可方便的应用于航海时确定经纬度。
由于地球的不规则性，在不同大圆上一分弧对应的长度也不同。因此现在广泛接受的国际标准的是1海里=1852m，计算时采用地球的平均半径。
