American missionary romanization
In 1842, Mission Press in Bangkok published two pamphlets on transliteration: One for transcribing Greek and Hebrew names into Thai, and the other, "A plan for Romanising the Siamese Language". The principle underlying the transcription scheme was phonetic, i.e. it represented pronunciation, rather than etymology, but also maintained some of the features of Thai orthography.[2]
Several diacritics were used: The acute accent was used to indicate long vowels, where Thai script had two different vowel signs for the vowel sounds: อิ was transliterated as i, while อี was transliterated as í. The exception to this rule was the signs for /ɯ/: อึ was transliterated as ŭ, while อื was transliterated as ü. The various signs for /ɤ/, were transliterated as ë. The grave accent was used to indicate other vowels: /ɔ/ was transliterated as ò, while /ɛ/ became è. ะ was transliterated with a hyphen, so that กะ became ka-, and แกะ became kè-. Aspirated consonants were indicated by the use of an apostrophe: บ b /b/, ป p /p/ and พ p’ /pʰ/. This included separating the affricates จ ch /tɕ/ and ช ch’ /tɕʰ/.
Proposed system by the Siamese society
For many years, the Siam Society was discussing a uniform way in which to transliterate Thai using Latin script. Numerous schemes were created by its individual members and published in its journal, including one tentative scheme by King Rama VI, published in 1913.[3] The same year, the society published a proposal for "transliterating Siamese words", which had been designed by several of its members working together. The system was dual, in that it separated Sanskrit and Pali loans, which were to be transliterated according to the Hunterian system, however, an exception was made for those words which had become so integrated into Thai that their Sanskrit and Pali roots had been forgotten. For proper Thai words, the system is somewhat similar to the present RTGS, for instance with regards to the differentiation of consonants' initial and final sounds. Some of the major differences are:
- Aspiration would be marked with spiritus asper placed after the consonant, so that ข and ค would both be transliterated as k῾ (whereas RTGS transliterates them as kh).
- Long vowels were indicated by adding a macron to the corresponding sign for the short vowel.
- The vowels อึ and อื (/ɯ/ and /ɯː/) would be transliterated using an umlauted u, respectively ü and ǖ (the macron is placed above the umlaut).
- The vowel แอ would be transliterated as ë, whereas RTGS transliterates it as ae.
- When ะ indicates a shortened vowel, it would be indicated with the letter ḥ, so that แอะ would be transliterated as ëḥ.
- The vowel ออ /ɔː/, would be distinguished from โอ with a superscript v: ǒ. Its corresponding short form เอาะ /ɔ/, would be transliterated as ǒḥ.
- The vowel เออ would be transliterated as ö.
As the system was meant to provide an easy reference for the European who was not familiar with the Thai language, the system aimed at only using a single symbol to represent each distinct sound. Similarly, tones were not marked, as it was felt that the "learned speaker" would be so familiar with the Thai script, as to not need a transliteration scheme to find the proper pronunciation.[4]
King Vajiravudh, however, was not pleased with the system, contending that when different consonants were used in the final position, it was because they represented different sounds, such that a final -ล would, by an educated speaker, be pronounced differently from a final -น. He also opposed using a phonetic Thai spelling for any word of Sanskrit or Pali origin, arguing that these should be transliterated in their Indic forms, so as to preserve their etymology. While most of Vajiravudh's criticisms focused on the needs and abilities of learned readers, he argued against the use of spiritus asper to indicate aspiration, as it would mean "absolutely nothing to the lay reader".[5]