The Jesuit or Roman Catholic liturgy was written in literary Chinese or "court Mandarin" (gǔ Wén). This literary style was not understand by common people. 

In expressing the sounds of Chinese names, James Legge followed the orthography of Morrison and Medhurst. In Morrison's A Dictionary of the Chinese Language, he followed the Jesuit method of representing the five tones of Mandarin Chinese, while Medhurst determined his own system of tonal marks, and nasal pronunciation (ng) and stop-ends (-h, k, p, t)( ' ) in his Dictionary of Hok-keen Dialect of Chinese Language, According to the Reading and Colloquial Idioms. His work relied on two Chinese compilations: the Imperial Dictionary (Kangxi dictionary) and a Southern Min rhyme glossary, entitled Collection of Refined and Vulgar Popular Fifteen Sounds.

Then it's Sir Thomas Francis Wade, his The Peking Syllabary was a collection of the characters representing the dialect of Peking; arranged after a new orthography in syllabic classes, according to the four tones. Designed to accompany the Hsin Ching Lu, or Book of Experiments, (Hong Kong), 1859. 

This syllabary was later amended, extended and converted into the Wade-Giles romanization for Mandarin Chinese by Herbert Giles in 1892. Thomas' Chinese name was Wei Tuoma (威妥瑪).