Books of Hours contained prayers and readings for the hours of the day prescribed for worship. They could be decorated in a manner befitting the wealth and position of the owner, and designed to the owner's taste. Books of Hours were small personal prayer books rather than large volumes intended for use in churches or monasteries. 

A Book of Hours generally begins with a Calendar which showed the days of the Church feasts and saints' days. This is usually the plainest part of a Book of Hours, certainly in the case of the Adelaide Hours. However red, blue and some gold lettering is used and highlight special days. Calendars can provide clues to the origins of a manuscript by including local saints for example the Adelaide Hours makes reference to the feast day of St Mustiola of Chiusi (3 July) where she is venerated as the patron saint. This indicates an origin in Tuscany, which is reinforced by the inclusion for a votive Mass for St Catherine elsewhere in the book, as there are catacombs in Chiusi dedicated to both of these saints. St Mustiola appears on the left hand page 6 lines down.

The calendar of a Book of Hours uses the Roman system of Kalends, Ides and Nones for each month and so each page begins with KL for Kalends. These letters are decorated with gold leaf. The calendar would be frequently consulted to check the date for a religious feast or other celebration and usually shows the most wear in a Book of Hours, often with the loss of pages. In the Adelaide Hours the pages are noticeably soiled.

The Adelaide Hours contains 19 thumb-nail sized historiated initials [initial capitals that contain an illustration that is relevant to the particular passage] and which are six lines high and introduce the main sections of the book. These are very elaborate with foliate and knotted motifs, highlighted in white. The predominant colours are blue, yellow, orange, green and pink with a lavish use of burnished gold. These initials contain a story, usually a moment in the life of Christ or of his mother the Virgin Mary. The letters are painted blue, pink and gold forming the frame for the image. The borders of these pages are composed of lavish acanthus foliage intertwined with various knots and other interlacings, and sometimes graced with fantastic beasts, birds and human figures. Burnished gold is used in the borders as well as in the letters.

Stocks, Bronwyn 'The Illustrated Office of the Passion in Italian Books of Hours' in The art of the book: its place in medieval worship edited by Margaret M. Manion and Bernard J. Muir Exeter: University of Exeter Press, 1998 pp. 111-152

The medieval imagination: illuminated manuscripts from Cambridge, Australia and New Zealand edited by Bronwyn Stocks and Nigel Morgan South Yarra, Vic.: Macmillan Art Pub., 2008 pp. 184-85

Fine books and book collecting: books and manuscripts acquired from Alan G. Thomas and described by his customers on the occasion of his seventieth birthday edited by Christopher de Hamel and Richard A. Linenthal Leamington Spa, Warwickshire: J. Hall, 1981 pp. 13-14: An Italian Book of hours circa 1375 by Margaret Manion

Manion, Margaret Medieval and Renaissance illuminated manuscripts in Australian collections by Margaret M. Manion and Vera F. Vines; with a foreword by K.V. Sinclair Melbourne: Thames and Hudson, 1984 pp. 70-71

The Cambridge illuminations: ten centuries of book production in the medieval West edited by Paul Binski & Stella Panayotova London: Harvey Miller, 2005

De Hamel, Christopher A history of illuminated manuscripts Oxford: Phaidon, 1986

Harthan, John Books of hours and their owners London: Thames & Hudson, c1977

The Medieval Imagination: Illuminated manuscripts from Cambridge, Australia and New Zealand. Interactive extras

Leaves of Gold: An introduction to Books of Hours

Treasures from the National Library: The Clifford Collection Book of Hours

State Library of South Australia: Treasures of the State Library: Italian Book of Hours

Santa Mustiola e sant'Ireneo martiri a Chiusi