Explanation of the final sounds終聲解
終聲者，承初中而成字韻。如卽字終聲是ㄱ，ㄱ居즈終而爲즉。洪字終聲是ㆁ，ㆁ居ᅘᅩ終而爲ᅘᅩᇰ之類。舌脣齒喉皆同。
The final takes up the initial and the medial and forms the sound of the letter. The final of the character 卽 jeuk is ㄱ; ㄱ stands at the end of 즈 to make 즉. The final of 洪 hong is ㆁ; ㆁ stands at the end of ᅘᅩ to make ᅘᅩᇰ. And so on in like manner. The tongue, the lips, the teeth and the throat are all the same.
聲有緩急之殊，故平上去其終聲不類入聲之促急。不淸不濁之字其聲不厲，故用於終則宜於平上去。全淸次淸全濁之字，其聲爲厲，故用於終則宜於入。所以ㆁㄴㅁㅇㄹㅿ六字爲平上去聲之終，而餘皆爲入聲之終也。然ㄱㆁㄷㄴㅂㅁㅅㄹ八字可足用也。如ᄇᆡᆺ곶爲梨花，여ᇫ의갗爲狐皮，而ㅅ字可以通用，故只用ㅅ字。且ㅇ聲淡而虛，不必用於終，而中聲可得成音也。ㄷ如볃爲彆，ㄴ如군爲君，ㅂ如ᅌᅥᆸ爲業，ㅁ如땀爲覃，ㅅ如諺語옷〮爲衣，ㄹ如諺語실〯爲絲之類。五音之緩急，亦各自爲對如牙之ㆁ與ㄱ爲對，而ㆁ促呼則變爲ㄱ而急，ㄱ舒出則變爲ㆁ而緩。舌之ㄴㄷ，脣之ㅁㅂ，齒之ㅿㅅ，喉之ㅇㆆ，其緩急相對，亦猶是也。且半舌之ㄹ，當用於諺，而不可用於文。如入聲之彆字，終聲當用ㄷ，而俗習讀爲ㄹ，盖ㄷ變而爲輕也。若用ㄹ爲彆之終，則其聲舒緩，不爲入也。訣曰
Since sounds differ in being slow or quick, the finals of the even, rising and high tones are not like the quick abruptness of the entering tone. The letters that are neither clear nor muddy are not strong in sound, and so when used at the end they suit the even, rising and high tones; the wholly clear, next-to-clear and wholly muddy letters are strong in sound, and so when used at the end they suit the entering tone. Thus the six letters ㆁㄴㅁㅇㄹㅿ serve as the finals of the even, rising and high tones, and all the rest serve as the finals of the entering tone.
Yet the eight letters ㄱㆁㄷㄴㅂㅁㅅㄹ are amply enough for use. ᄇᆡᆺ곶 is a pear blossom and 여ᇫ의갗 is a fox pelt, and since the letter ㅅ can be used throughout, only the letter ㅅ is written. Moreover ㅇ is clear and empty in sound, so that even without being written at the end, the medial alone can form the sound.
ㄷ is as in 볃 standing for 彆 byeol, ㄴ as in 군 standing for 君 gun, ㅂ as in ᅌᅥᆸ standing for 業 eop, and ㅁ as in 땀 standing for 覃 dam; and ㅅ is as in our own word 옷〮 meaning a garment, and ㄹ as in our own word 실〯 meaning thread, and so on.
The slow and the quick among the five notes are likewise paired each with each. Among the molars, ㆁ and ㄱ are a pair: call ㆁ out quickly and it turns into ㄱ and becomes abrupt; draw ㄱ out slowly and it turns into ㆁ and becomes slow. The lingual ㄴ and ㄷ, the labial ㅁ and ㅂ, the dental ㅿ and ㅅ, and the guttural ㅇ and ㆆ are likewise paired each with each in their slowness and quickness, just as these are.
Further, the semi-lingual ㄹ is for use in our own language and cannot be used for Chinese. The character byeol, being of the entering tone, ought properly to take ㄷ as its final, but by common habit it is read with ㄹ; in general this is ㄷ changed and made light. If ㄹ is used as the final of the character byeol, its sound drags out and does not become the entering tone. Let us sing it in brief.
不淸不濁用於終 爲平上去不爲入 全淸次淸及全濁 是皆爲入聲促急 初作終聲理固然 只將八字用不窮 唯有欲聲所當處 中聲成音亦可通 若書卽字終用君 洪彆亦以業斗終 君業覃終又何如 以那彆彌次第推 六聲通乎文與諺 戌閭用於諺衣絲 五音緩急各自對 君聲迺是業之促 斗彆聲緩爲那彌 穰欲亦對戌與挹 閭宜於諺不宜文 斗輕爲閭是俗習
When a sound neither clear nor muddy is used at the end it becomes the even, rising or high tone, and not the entering tone. The wholly clear and the next-to-clear and the wholly muddy all become the entering tone, and are quick and abrupt. Making the initial serve as the final is of itself the principle, and with only eight letters the uses of it are never exhausted. Only where yok would properly be placed, the medial alone forms the sound, and it serves. To write the character jeuk, put gun at the end, and hong and byeol are closed off with eop and du. And the finals of gun and eop and dam — what of them? Work through them in order with na and byeol and mi. Six of the sounds serve throughout for Chinese and for our own speech, and sul and ryeo are used for our words for garment and thread. The slow and the quick among the five notes are paired each with each: gun is just eop brought out quickly, and du and byeol, with the sound drawn out, become na and mi. yang and yok are paired in turn with sul and eup. ryeo suits our own language and does not suit Chinese, and du made light and turned to ryeo is a habit of common usage.