The Development of Norman Barrel Vaulting
Banister F. Fletcher
Source: A History of Architecture on the Comparative Method (5th ed), plate 112D (p. 286)
The Roman system was in vogue up to the twelfth century, but the introduction of transverse and diagonal ribs in this period rendered temporary centering necessary for these. In England the raising of the diagonal rib, which produced the domical vault employed on the Continent, seems to have been but little used, and the method was either (a) to make diagonal ribs segmental, as in the aisles at Peterborough Cathedral; or (b) to make the diagonal ribs semicircular and stilt the springing of the transverse and longitudinal ribs.