measured it myself, I should have been somewhat doubtful of 
the correctness of the diagram. This is a most excellent exam- 
ple, now fast falling to decay. It cannot be described, but it will 
be seen that it (curiously enough) includes the very same lines 
as those in the diagrams, showing the identity of principle in 
the plans of York, Lichfield, and SaUsbury Cathedrals, (plate 
3, Nos. 1, 2, 3,) and also those by which the window termed 
vesica piscis" (plate 1, No. 15) is produced. The whole 
of these arcades display the use of geometry; and a careful 
attention in taking the admeasurements of others, would 
doubtless give rise to a very simple mode of classification, as 
to the variety of forms which the heads may be made to 
assume. 
BUTTRESSES, FLYING BUTTRESSES, AND VAULTING. 
I have already remarked, that the thick walls of Norman 
and Saxon buildings were capable of resisting the slight 
thrust of the vaulting, and that therefore the Norman buttress 
is merely a thin slab of masonry, introduced on the face of 
the wall for the purpose of giving relief by the light and 
shade which it creates, (this may be seen in Kirkstall 
Abbey, &c.) The projecting buttress arose from necessity 
so soon as the cathedrals were acutely vaulted; and connected 
with these buttresses are found some of the most beautiful 
ornamental accessories of the pointed style, such as pinnacles, 
niches, canopies, &c. 
With respect to the caps of early English buttresses, which 
are triangular on the face, certain rules appear to have been 
-observed, which have, I think, hitherto escaped notice. I 
find, both from actual measurement, and the examination of 
engraved geometrical drawings of acknowledged accuracy, 
that the side of the buttress-cap, if continued, generally 
cuts either the angle or the centre of the window-sills : two 
or three illustrations may suffice as corroborative of the fact — 
(some are omitted in the plate.) 
