The system is quite sensible. The English j and ch are close relatives as the latter is just an aspirated version of the former. In Wade-Giles, the English j sound is represented by ch, an unaspirated English “ch” sound. The English “ch” sound is represented in W-G by ch’. Note the apostrophe in this case indicating an aspirated initial. Following this to its logical conclusion, the English k is represented in W-G by k’ while the unaspirated version k is equivalent to a hard English g. Similarly, English t = W-G t’ while English d = W-G t.[/quote]
But again… why go through all of the complication? When it just so happens that the aspirated j almost perfectly corresponds to the sound in 句, and the unaspirated ch almost perfectly corresponds to 吃? :s[/quote]
Hmm…I’m not sure I understand your point.
English ch, an aspirated sound, is equivalent to a Hanyu Pinyin q, which is equivalent to a Wade-Giles ch’. Let’s take the character 去; if you were to spell this using English phonetics, you will end up with something like cheeyu or chiu or ch…, the point being that it’ll start with “ch”. In Hanyu Pinyin, it starts with q (qu4), does that make sense at all in your opinion? In W-G, it is ch’ü. In this case, W-G is closer to English than Hanyu Pinyin.
Now let’s transform the W-G ch’, an aspirated sound, and make it an unaspirated sound. It then becomes an English j sound, which is also a j in Hanyu Pinyin, but is a ch in W-G (just remove the apostrophe for unaspirated). For the character 句, English phonetics may end up being juu or jeeyoo or j… while the Hanyu Pinyin is ju and the W-G is chü. From an English speaker’s perspective, in this case, the Hanyu Pinyin is closer. However, W-G makes more sense logically because 去 and 句 are actually very close in pronunciation. The only difference is aspiration. W-G makes clear their interrelationship by having both character transliterated in the same way save an apostrophe while the same cannot be said for Hanyu Pinyin or any other romanization scheme that I’m aware of.