wikipedia上的Peking

首先是德文版，Peking:

Peking (chin. 北京 Běijīng, W.-G. Pei-ching) ist die Hauptstadt der Volksrepublik China und hat eine über dreitausendjährige Geschichte. Der chinesische Name lässt sich mit Nördliche Hauptstadt übersetzen. Peking ist heute eine Regierungsunmittelbare Stadt, das heißt sie ist direkt der Zentralregierung unterstellt und damit Provinzen, Autonomen Gebieten und Sonderverwaltungszonen gleichgestellt.

英文版里对Peking的描述，是在"Beijing"条目中：

The traditional customary name for Beijing in English is Peking. The term originated with French missionaries four hundred years ago, and corresponds to an older pronunciation predating a subsequent sound change in Mandarin from [kʲ] to [tɕ]. ([tɕ] is represented in pinyin as j, as in Beijing.)

而右侧表格中对于Beijing 的Name的描述中有：

Name	Chinese characters: 北京 Pinyin: Běijīng Wade-Giles: Pei-ching; Postal System Pinyin: Peking

那么，Postal System Pinyin条目里又是怎么说的呢：

In the early twentieth century, China (starting with the dying Qing Empire) used Postal (Office) System Pinyin (Traditional Chinese:郵政式拼音 Pinyin: Yóuzhèngshì Pīnyīn) (unrelated to the modern Hanyu Pinyin), based on Wade-Giles (in particularly, Herbert Giles's A Chinese-English Dictionary) for postal purposes, especially for placenames on letters and stamps, and was not for universal usage. It uses some already common European names of Chinese places that override the Wade-Giles system, and incorporate some dialectal pronunciations.

The postal system was decided after the Imperial Postal Joint-Session Conference (帝國郵電聯席會議) in spring 1906 in Shanghai.

Main differences with Wade-Giles include:

• Complete lack of diacritic and accent marks.
• Chi, ch'i, and hsi (pinyin ji, qi, and xi) are represented as either tsi, tsi, and si or ki, ki, and hi depending on historic pronunciation, e.g.,
  • Peking (Pei-ching, Beijing)
  • Tientsin (T'ien-chin, Tianjin)
  • Tsinan (Chi-nan, Ji'nan)
• Except being the sole vowel in the syllable, the Wade-Giles u become w, e.g.,
  • Ankwo (An-kuo, Anguo)
  • Chinchow (Chin-chou, Jinzhou)
• Guangdong, Guangxi, and Fujian placenames are to be Romanized from the local dialects, such as Hakka, Cantonese, and Min (systems also obtained from Giles' A Chinese-English Dictionary).
  • Amoy (Hsia-men, Xiamen)
  • Swatow (Shan-t'ou, Shantou)
  • Quemoy (Chin-men, Jinmen)
• Popular pre-existing (from 19th century of earlier) European names for place in China are to be retained, such as those of the treaty ports.
  • Canton (Kuang-chou, Guangzhou)

See also: Romanization

这样看来，很多问题就容易解释多了。Peking是大清帝国官方用过的邮政拼音系统，似乎没有太大的疑问。尽管网上关于“帝國郵電聯席會議”的资料实在不多，但是，对待历史问题必要的考据癖总是比无端臆测来得更加有用一点。