Angela Mariani, Improvisation and Inventio in the Performance of Medieval Music: A Practical Approach. New York: Oxford University Press, 2017. xxi + 232 pp. £71 (hardback) / £18.99 (paperback). ISBN 978 0 19 063117 8 (hardback), 978 0 19 063118 5 (paperback).

levels of formality: the size and spacing of his diamond-shaped noteheads could be adjusted, or abandoned altogether in favour ofmore quickly executed teardrop shapes, yet enough remains constant in De Blauwe’s work to convince us that his work pervades these sources. De Blauwe must also have been responsible for the calligraphic initials in MSS 1438–1440. Jas does not suggest this, but one of the weapons in De Blauwe’s scribal armoury when executing the more elaborate initials (see the cover of Jas’s book, and his Plate 16 on p. 103) may have been a broad-nibbed pen with a nick excised towards the right edge of the nib, producing at a single stroke a broad line on the left and a parallel narrow line on the right. We must be grateful to Dr Jas for presenting his work in such elegant English, and his publisher has served him reasonably well. It is regrettable that a decision was taken to reproduce the watermarks (in Appendix 3) smaller than their actual size, since this makes potential comparison with other examples much more difficult (and this is all the more frustrating when the list of concordant sources – important as it is – is presented on pp. 349–93 in a much larger typesize and a more extravagant layout than necessary). The proofreader might perhaps have spotted twenty or so occurrences of ‘epynomous’ (sic) in the manuscript inventories, not to mention some of the stranger end-of-line hyphenations (‘notehe-ads’, pp. 111, 116; ‘semim-inims’, p. 131). But, of course, none of this detracts from the value of Jas’s important and thorough research and his impressive presentation of it in this book.