The Octave Day of Corpus Christi is of greater double rite. Only the feasts of the Nativity of St. John the Baptist and SS Peter and Paul can be celebrated on the Octave Day. Other Doubles of the First Class are transferred if they fall on this day.
At Vespers yesterday the antiphons Sacerdos in aeternum etc were sung, doubled, with the psalms, chapter and hymn etc as on the feast. The antiphon on the Magnificat was O quam suavis est as at First Vespers of the feast itself. A commemoration was sung of St. Margaret Queen of Scotland.
At Mattins all is sung as on the feast except the lessons. In the first nocturn these continue to be read from the first Book of the Kings. In the second nocturn the lessons are taken from a Sermon of St. Cyrill of Jerusalem and in the third nocturn the homily is from St. Cyrill of Alexandria. The responsories are those of the feast, that have been used thoughout the Octave. At Lauds all is sung as on the feast but, in addition, a commemoration of St. Margaret is sung.
The Mass Cibavit is sung after Terce. The Gloria is sung, the second collect is of St. Margaret, the Sequence Lauda Sion is sung, the Creed is sung and the preface is of the Nativity.
The Caeremoniale Episcoporum directs, C.E. Lib II, Cap. XXXIII, #34, directs that a Procession with the Sacrament take place after Vespers on the Octave Day of Corpus Christi. However, with changes in made in the first part of the twentieth century Second Vespers were no longer celebrated and replaced by First Vespers of the Sacred Heart.
In the 'liturgical books of 1962' of course the Octave Day has gone. Today becomes a III class feast without first Vespers, with a single nocturn etc.