This is a collection of essays in which the honorand can take pride as well as pleasure, including a number of definitive or pioneering studies. They fall into groups which reflect the range of Busard's own work and interests. The first of these is concerned with Arabic mathematics in its own right, and with its influence in the West. Notable here is A. Djebbar on ''Deux mathe Β΄maticiens peu connus de l'Espagne du XI e sie `cle,'' which helps to make newly accessible the preoccupations of the work of this place and period and to identify the lacunae and disjunctions which make it difficult to fit Al-Mu'taman and Ibn Sayyid tidily into the picture. Y. Dold-Samplonius writes on ''The Volume of Domes in Arabic Mathematics.'' This is an extension of the theory of mensuration derived from the Roman agrimensores, and it presents special problems because a dome, as Al-Ka Β―shΔ± Β―points out, may take several forms. It may be a hollow hemisphere, a segment of a hollow sphere, a polygonal cone, or a construction made by, in effect, rotating the form created by the facade of an arch. Al-Ka Β―shΔ± Β―was a practical man, and the strategies he devised for arriving at a close approximation of the volume of the more complex shapes show an economy which reflects his grasp of the realities of construction. From the four manuscripts and three versions extant, J. P. Hogendijk provides a text and literal translation of ''The Arabic Version of Euclid's On Divisions,'' lost in its Greek original and surviving only in a Persian abstract compiled in the 10th century. J. Sesiano deals with the 14th-century Latin version of the Algebra of Abu Β―Ka Β―mil. He draws out the special interest of the mode of translation used at this relatively late date. B. A. Rosenfeld briefly examines ''Geometrical Trigonometry'' in several Arabic treatises, contending that rules were in use ''equivalent to theorems of spherical trigonometry.''
There is a preponderance of papers on geometrical issues, some of them also falling into the ''Arabic'' category of the volume and already noted. R. Lorch writes on ''Abu Β―Ka Β―mil on the Pentagon and Decagon,'' with an edition of the Latin text and an invaluable discussion of the technical vocabulary. G. Molland edits and translates Roger Bacon's Geometrical Speculativa. S. Brentjes discusses the variants of a H . ajja Β―j-version of Book II of the Elements. What Charles Burnett has to say