“中国”的英文直译，Middle Kingdom 还是Central Country？

英语文献中，中国当然是China，但是有时为了表达“中国”的含义，一般都是用Middle Kingdom来翻译，几乎很少看到用Central Kingdom（Country）来翻的。

在Conflict in the Far East，《远东冲突》一书中（副标题是1928年到1933年美国在中国的外交。作者是James William Christopher，由E. J. Brill 1950年出版），作者说，（p11）This nation, which many Westerners have been wont to dismiss with a shrug or with some statement about its queerness and backwardness, has indeed been accustomed in the past to consider itself the hub of the universe, as is shown by the standard Chinese name for their own land--Chung Kuo, the Central Country 。他说中国翻译成英文用Central Country。
这本书比较老，1950年的。近来陈兼教授（康奈尔的胡适教授席位拥有者）也说过同样的话，见他在Origin of the Cold War， an International History second edition  冷战起源（Melvyn P. Leffler 和 David S. Painter 编辑， Routledge 出版社 1994年出版）一书中的一篇文章--Mao and Sino-American Relations 毛泽东和中美关系--中说（p294的第二条注中）: I believe that "Central Kingdom" is a more accurate translation for "Zhong Guo"(China) than "Middle Kingdom." The term "Middle Kingdom" does not imply that China is superior to other peoples and nations around it--China just happens to be located in the middle geographically; the term "Central Kingdom", however, implies that China is superior to any other people and nation "under the heaven" and that it thus occupies a "central" position in the known unverse.   Middle仅仅是个地理上的概念，而Central则表达了中国高于其他人民和国家的思想。

另一本，《爱恨中国》（Love and Hate in China）作者是Hans Koningsberger，McGrow-Hill Book Company 1966年出版。里面第4页，也谈到这个问题，...China--both called, and both considered, by their inhabitants Zung Ghuo, the Central Country or Middle Kingdom as it used to be translated into English.  

还有一本书是《冷战起源》（Origin of the Cold War：an International History，作者是Melvyn P. Leffler and David S. Painter，2nd edition，出版社是Routledge，于2005年出版。），这是本论文集，里面陈兼的论文里也谈到这个问题，第285页上，说中国在历史上称为Central Kingdom，然后在第294页上的注释2里说，作者认为“中国”的翻译，Central Kingdom比通用的Middle Kingdom更准确：‘The term ”Middle Kingdom“ does not imply that China is superior to other peoples and nations around it--China just happens to be located in the middle geographically; the term "Central Kingdom," however, implies that China is superior to any other people and nation "under the heaven" and that it thus occupies a "central" position in the known universe.'  跟上面陈兼的说法是一样的。

20190202补：David Mulroney于2009年至2012年任加拿大驻中国大使，在他的书Middle Power，Middle Kingdom：What Canadians need to know about China in the 21th Century( Allen Lane, an imprint of Penguin Canada Books Inc, 2015,也把中国称为Middle Kingdom，写在了书名里。