From Liturgies of the Religious Orders by Archdale King, 1955, pp. 290, 321-322, 374.
A liturgical fan (flabellum) of leather, silk, parchment or feathers was used in the sacrifices of the heathen and from very early times in the Christian Church. The Apostolic Constitutions (late 4th century) say: “Let two of the deacons, on each side of the altar, hold a fan, made up of thin membranes, or of the feathers of the peacock, or of fine cloth, and let them silently drive away the small animals that fly about, that they may not come near to the cups”. John Moschus relates the story of an Italian bishop, offering the Holy Sacrifice in the presence of Pope St. Agapitus I (535-536), who requested the Pope to tell the deacon with the flabellum to go away from the altar at the prayer of the holy oblation. Hildebert de Lavardin, bishop of Tours (1135-1134), sending a flabellum to a friend, says:
And so, when you drive away flies descending upon the Sacrifice with the fan I sent to you, you ought to ensure the onslaught of temptations is driven away from the mind of the celebrant with the winnowing-fork of the Catholic faith. This is so that what is taken up for use may proffer you mystical understanding.
The fan was in use in Ireland in the early Middle Ages, and it is mentioned in various texts of the period, while the ornament itself is represented in ancient Irish illuminations. A Hiberno-Saxon manuscript of the gospels (8th century) at Trier depicts a fan in the right hand of St Matthew, and the monogram of the Book of Kells (8th century) shows angels bearing a fan which seems to be made of thin plates of metal surrounded by little bells.
The liturgical fan was commonly used in Rome and the West generally from the secret till the end of the canon during the Middle Ages. Its use has been described in the Cluniac customary: One of the servers (they must always be two), standing with a fan near the priest, does not neglect to keep flies away from the Sacrifice, the altar, and the priest himself from the moment the infestation begins until it ends.
Ordo Romanus XIV (14th century) prescribes the fan, si tempus requirit, and a pontifical ceremonial of the time of Pope Nicholas V (1447-1455) gives the rubric: “Let them also carry fans during summertime in order to drive flies away from the service.” The sacristan is reminded in the ordinarius of Liège (c. 1285) to provide a flabellum “in the season of flies” for the private Masses of the brethren, as well as for the conventual Masses. Its use is attested also by Durandus of Mende (ob. 1296).
The use of a fan as a liturgical ornament seems to have disappeared from the Western Church, except in the Carmelite and Dominican Orders, after the council of Constance (1415), continuing merely as part of the honorific insignia of the Pope on solemn occasions. It exists today in the Eastern Church in the Syrian (Marwaḥ’tḥo), Byzantine (ripidion), and Armenian (keshotz) rites. A ripidion is given to the Byzantine deacon at his ordination.
In the case of the Carmelite rite, the ordinal of Sibert of Beka (1312) gives the following rubric: During fly-season after the beginning of the secrets the deacon must hold a fan with which becomingly to prevent them from bothering the priest, and drive them away from the Sacrifice. It was repeated in the ordinal of 1544, but the ceremonial of 1616 permitted its use to be optional. The variations of usage were described in an appendix to the ceremonial of 1906, without, however, committing itself as to whether the fan should still be used:
During fly-season, the deacon (and even the server in a private Mass) must, according to the Ordinal of the Divine Office of 1544, and may, according to the Ceremonial of 1616, hold a fan in his hand after the beginning of the secrets, and with it becomingly prevent them from bothering the celebrant and drive them away from the Sacrifice, as is still the custom in some places. For the server at private Mass, it is added: and to make the priest a bit more comfortable … especially in hot climates.
Fr Zimmerman says that its use has never been entirely abandoned, but he fails to say in what provinces it may be found. A Carmelite of the Irish province told the writer (1949) that the flabellum has figured in some churches in recent years for the rite of 1504, but as a ceremonial adjunct rather than as a fan for the oblata. It was formerly used by the deacon (server at a private Mass) from the beginning of the secrets until the end of the canon.
The oldest known Dominican missal, from Paris (c. 1240), there is an illustration in which the priest is depicted at the altar, assisted by a deacon waving a flabellum. The actual ceremonial of the Order (1869), gives a rubric similar to that in the Carmelite ordinal of Sibert: During the season of flies the deacon uses a fan to drive flies away, lest they bother the priest. A note says that the fan is still in use in a few houses.
 Apost. Const., VIII, cap. XXII.
 Prati Spiritualis, cap. CL
 Dum igitur destinato tibi flabello descendentes super sacrificia muscas abegeris; a sacrificantis mente supervenientem incursus tentationum Catholicae fidei ventilabro exturbari oportebis. Ita fiet ut quod susceptum est ad usum, mysticum tibi praebeat intellectum. Epist. VIII.
 Irish culebad; Old Irish culebath.
 Unus ministrorum, qui semper duo debent esse, stans cum flabello prope sacerdotem, ex quo muscarum infestatio exurgere incipit, donec finiatur, eas arcere a sacrificio et ab altari, seu ab ipso sacerdote non negligit.
 Deferant quoque aestivo tempore flabella ad eijiciendas muscas a ministerio.
 Tempore etiam muscarum post inceptionem secretarum debet diaconus tenere flabellum quo cohibeat eas honeste a molestando sacerdotem, et abigat a sacrificio.
 Juxta Ordinale divini officii anni 1544 debet et juxta Caeremoniale 1616 poterit diaconus (et etiam minister in missa privata) tempore muscarum post Secretorum incoeptionem Flabellum in manu tenere, quo eas honeste a molestando celebrante cohibeat et a Sacrificio abigat, prout adhuc alicubi usus est. Pro ministro in Missa privata additur: atque ad Sacerdotem aliquantulum consolandum … praecipue in locis calidis.
 Tempore vero muscarum Diaconus utatur flabello ad abigendas muscas, ne molestent sacerdotem.