The book comprises 348 leaves of vellum. Nearly a third of these are replacements. The book was designed to be easily carried: hence its pages are small, measuring 13.1 x 9.3 cm. It contains 64 full-page miniatures and 140 text pages with decorated borders and small miniatures. Its binding, in dark red
Morocco, dates from around 1896. Birago's miniatures are in the North Italian antiquarian style of
Andrea Mantegna. Horenbout's additions to the Sforza Hours demonstrate a deliberate attempt to adapt his own style to a more Italianate one that would complement Birago's existing illuminations. Horenbout's
Saint Mark (fol.10.v), for example, has similar features to Birago's
St Matthew (fol.7.r), such as the Italian Renaissance architectural setting and the scroll in the foreground. The framing of the miniatures with gold frames with simple mouldings, imitating the wooden frames of contemporary
panel paintings, can also be seen in the French
Grandes Heures of Anne of Brittany of 1503–1508.
Calendar Only
May (British Library, Add. MS 62997) and
October (British Library, Add. MS 80800) by Birago are known to exist from the calendar. The calendar probably belonged to the stolen part of the manuscript about which Birago complained in his letter.
Gospel lessons The Gospel lessons contain the following miniatures:
St John (fol.1.r),
St Luke (fol.4.r), and
St Matthew by Birago and
St Mark by Horenbout (fol.10.v). Half the contents of the Gospel lessons are replacements. The varying quality of Birago's miniatures in this section is evidence of extensive studio collaboration.
Hours of the Cross This includes a full-page miniature by Horenbout of
Christ nailed to the Cross (fol.12.v). This miniature has been likened to
Gerard David's panel of the same subject (in the
National Gallery, London), but it is possible that Horenbout may have seen the subject in the
Hours of Mary of Burgundy which displays similar details to Horenbout's painting. The section also contains 18 decorated borders by Birago.
Hours of the Holy Spirit This section has survived completely intact. It contains the
Descent of the Holy Spirit (fol.28.r) and twenty-one decorated borders by Birago.
Hours of the Virgin This part includes 8 full-page miniatures by Horenbout, including the
Visitation (fol.61.r) and the
Adoration of the Magi (fol.97.r) (Birago's miniature of the
Adoration of the Magi also exists (British Library, Add 45722)), and 44 decorated borders by Birago. The
Visitation includes a portrait of Margaret of Austria as the Virgin's cousin
Elizabeth. It is possible that Margaret possessed a desire to identify herself and her situation with the aged and childless Elizabeth.
The accessory prayer Salve Regina Includes a full-page miniature by Horenbout of the
Virgin and Child in Glory (fol.133.v).
Passion according to St Luke This section contains the
Entry into Jerusalem (fol.136.v) by Horenbout and 8 miniatures that represent a complete Passion cycle by Birago. These include the impressively composed
Last Supper (fol.138.v).
Seven prayers of St Gregory These prayers contain a full-page miniature of the
Mass of St Gregory (fol.167.r) and 5 decorated borders by Birago depicting Passion scenes.
'Obsecro Te' and 'O Intemerata' A substantial portion of this section consists of replacements. Birago's
Assumption of the Virgin (fol.170.r), however, has survived. There is also a full-page miniature by Horenbout of the
Virgin and Child (fol.177.v).
Suffrages of the Saints This is considered the finest cycle of decoration in the Sforza Hours. It contains 25 vibrant and dynamic miniatures by Birago of individual saints, arranged in order of importance, beginning with
St Michael (fol.186.v) and ending with
St Mary Magdalene (fol.211.v) (this has been misplaced in the series – it should end with
St Clare (fol.210.v). The series contains one Horenbout miniature:
St Andrew (fol.189.v).
Seven Penitential Psalms In this section there is a full-page miniature by Horenbout of
King David in Penitence and six miniatures of the same subject by Birago. There is also one decorated border by Birago (fol.213.r) to which Horenbout added the portrait of Charles V.
Litany More than half the folios of the Litany are replacements. It includes one miniature, the
Procession of St Gregory (fol.236.r), and 8 decorated borders by Birago depicting Old Testament heroines and female saints.
Office of the Dead This part contains one miniature by Horenbout, the
Raising of Lazarus (fol.257.v). There is one miniature, the
Death of the Virgin and 41 decorated borders by Birago. Nearly a third of this section is replacements. The Office of the Dead is followed by the Prayer of the name of Jesus from the epistles of St Paul (fols 343.r-348.v) which is an unillustrated addition of around 1600. ==Gallery==