Here is a beautiful proper tone for the traditional epistle of the feast of the Holy Innocents, Apocalypse 14, 1-5. (Click here to see a downloadable pdf version in two pages.)
Here are Henri de Villiers’ notes on the chant:
This special chant for the Epistle of the feast of the Holy Innocents (28 December) was once chanted with interwoven French verses that paraphrased the Latin text. In the Middle Ages this was called a farced epistle. These epistles were chanted by two or three subdeacons on certain feasts of the year, especially during the period around the feast of Christmas, from St. Nicholas to Epiphany. We find farced epistles very frequently in liturgical manuscripts from the 12th to the 13th centuries, after which the practice seems to decline and disappear. Some however were composed as late as the 14th century, and were still sung with their texts in Old French in certain provinces of France into the middle of the 18th century, especially the epistle of St. Stephen, which is probably the most ancient. For linguists who study the history of the French language, these farces are very valuable because they represent some of the most ancient written witnesses of French, as expressed in numerous regional forms.
Here is the beginning of the Epistle of the Holy Innocents transcribed by Fr. Lebeuf in his famous Treatise on ecclesiastical chant, with tropes in Old Picard. (See the full trope with musical notation here):
Now listen, old and young, draw near to this writ. If ye listen to what this lesson sayeth and what it singeth, I ask you all that each one pray, that the Lord God may come dwell in us, and take his rest in our hearts, and not forget our end.
A Lesson from the book of the Apocalypse of blessed John the Apostle. Hearken ye to the sense and reason of Saint John’s vision. They call it “Apocalypse,” the raising of the house, and of the lofty house that God promiseth us in his name, by the Gospel and by the sermon. We must not doubt that he sayeth in his lesson.
In those days, I saw the Lamb standing upon Mount Sion, and with Him a hundred and forty-four thousand having His name and the name of His Father written on their foreheads. In those days whereof I sing to ye, Saint John saw a very large mount. Sion is its name, and on its slope there is a standing Lamb. Accompanying Him are a hundred and forty thousand children, and four thousand more withal, and in the midst of their forehead above their faces they bear the name of the living God. Mount Sion is the Holy Church, which the Lord God made and placed upon a firm and well-founded stone, and He taught Her with Scripture, which doth crush and break the haughty, and doth blow and kindle charity. But the sinner hath chosen another way, by evil counsel and by lust. He rendereth a smoky wind for flame, and doth separate himself from God’s love exceedingly. This Lamb is atop the mount, very beautiful, very good, with true wool. With Him is a very large company, but none in this multitude matches Him. It is Jesus Christ of Nazareth, Who through the heavens, on a broad plain, taketh up again and again the Innocents, they who praise God with healthy voice.
And I heard a voice from heaven like a voice of many waters, and like a voice of loud thunder; and the voice that I heard was as of harpers playing on their harps. From afar I heard the waters turn, just like the sea, and then I heard loud thundering and the clash of thunder. Then I heard the sound of harps, harpers with song. Now, we must explain this well: Our deeds, our words, and our thoughts, that we can bring together, we must give over to the Lord God. The waters are the great multitude, the bad, the good, and the incredulous, which God made to be born on earth, as many as there are flowing waters. All must in their lives praise the Lord God almighty. And the thundering I heard from God is what he shall threaten us with, thrashing us with want, and chastising us with hunger and war, as a father his child. The harps produce a melody, while man says a psalmody, and he afflicts himself with fasting when he hath no hypocrisy. Without pride and without envy, he singeth to God in symphony, and rendereth to Him a sweet harmony.
And they were singing as it were a new song before the throne, and before the four living creatures and the elders; and no one could learn the song except those hundred and forty-four thousand, who have been purchased from the earth. Those whom I mentioned, the children, will sing a song the like whereof no man hath ever heard. The news was of a new sound: it is called the Gospel, and none can hold the tone, besides the companions.
These are they who were not defiled with women; for they are virgins. These follow the Lamb wherever He goes. Those who love virginity, and resolved in their hearts to keep their bodies in purity, can serve the Majesty that is of such great power. Those who have besmirched themselves and amused themselves in filth, and have shriven themselves well, and purified and cleansed themselves, shall be able to follow in tranquillity the Lamb of such great holiness.
These were purchased from among men, first-fruits unto God and unto the Lamb, and in their mouth there was found no lie. These Innocents are the first whom God suffered to be martyred, and be struck and broken down, and be defleshed on the rocks. The tyrant and the butcher, for the sake of Jesus Christ our prince, sought to kill and slay them, for Herod who wished to reign alone, with no other heir. When the tyrant beheaded them, their vermilion blood did flow, and while milk appeared, which they had first suckled from their mother, from the mouth that held her. And when the children beheld the bright sword that shone, they laughed on account of their age, for without fail when they looked they bethought that they were playing in that spot.
They are without blemish before the throne of God. For they are without any blemish, and without care of this world. To God’s holy nature they have well offered their likeness and figure as a pure offering. They shall never suffer a harsh word, if, as Holy Scripture sayeth, throughout all the days that the world should last, God shall grant them sweet pasture, and God, as good nourishment! Now, let us pray to God very simply that He might grant us amendment, and He shall sweetly hearken to us. He desireth to take us at His will hither to our end, and stand for us soit on the judgement day. Thereafter he shall give us a dwelling in Paradise, as His gift. Now, say ye all: Amen! Amen!
The French paraphrase is set in the same 7th mode as the cantillation for the Latin text, but the chant is not set to the same melody. In other farced epistles, all the strophes reproduce the same melody, distinct from that of the Latin which develops more freely from one verse to the other. It is probable that the French verses were composed to be inserted into the pre-existing Latin cantillation.
Are these cantillations, at least with regard to the Latin text, very ancient? Probably. They are found with similar melodies from one diocese to another. The two examples Fr. Lebeuf gives of the farced epistle of the feast of St. Stephen (26th December), taken from the books of Amiens (1250) and from a church in the province of Lyon or Sens (1400) contain very similar melodies—both French and Latin—but with different words for the French paraphrases (except the first strophe).
Hence the farced Epistles are precious because they let us hear an echo of the great variety of liturgical cantillations that must have been in use to chant the various Epistles and Gospels of the year. Thus they are a memory of an ancient stage of the liturgy, much richer than what has come down to us. (The Roman liturgical books since the 17th century contain only two tones for the Epistle, one being recto-tono.)
The chant for the Epistle of the Holy Innocents cited by Lebeuf is taken from the ancient liturgical books of Amiens. The French trope contains a full 130 verses all in masculine rhymes to facilitate their adaptation to plain-chant. Our schola preserves the chant of the Latin verses, without the French paraphrases, and we have completed the first verses provided by Fr. Lebeuf based on a 19th-century work by Dr. Rigollot. The 7th mode, which naturally has a wide range, was perhaps chosen based on the meaning of the text. The melody rises in the second verse to express the text:
Et audivi vocem de coelo, tamquam vocem aquarum multarum, et tamquam vocem tonitrui magni.
And I heard a voice from heaven, as the noise of many waters, and as the voice of great thunder. (Apocalypse 21:14)
Note that the 4th verse especially (and to an extent the 5th verse) imitates the psalmody of the 7th mode, and this psalmody might have inspired the entire cantillation for the Epistle on Childermas.
Although the Parisian books do not preserve any farced epistles, this might be because few liturgical manuscripts from Paris from before the middle of the 18th century have survived. Must we conclude that the diocese of Paris rejected the singing of farced epistles?
No! In an interesting ordinance promulgated in 1198 by bishop Odo of Sully to regulate the celebration of the feast of the Circumcision on the 1st of January in Paris, we find the following passage, which demonstrates that this city, like the other dioceses of France, also farced epistles:
Missa similiter cum ceteris Horis ordinate celebrabitur a aliquo prœdictorum, hoc addito quod Epistola cum farsia dicetur a duobus in cappis sericeis.
The Mass shall be celebrated like the rest of the Hours by one of the aforesaid, with the addition of a farced Epistle which shall be said by two ministers in silken copes.
 A 16th-century Missal from Cluny, for instance, provides different melodies for each rank of liturgical day.