So, let's go back to the thrilling days of the end of the 19th century, and just take stock.

让我们回到激动人心的,19世纪末，稍微想一下。

麻省理工公开课 - 固态化学导论课程节选

It is an electron beam. In the 1890s, the latter part of the 19th century a very fashionable word was "ray."

那是个电子束，在十九世纪九十年代，就是19世纪末,一个很时髦的词汇-“光线“

麻省理工公开课 - 固态化学导论课程节选

Also, we don't have accurate censuses until the 19th century.

况且,直到十九世纪我们才有了,精确的人口普查

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What did we know at the end of the 19th century about the structure of the atom?

在19世纪末,关于原子结构我们了解多少呢？

麻省理工公开课 - 固态化学导论课程节选

This went out at the end of the 19th century, and so on.

这在19世纪末期后就结束了。

麻省理工公开课 - 固态化学导论课程节选