234 The Churches of Purton and Wanborough. 
The western tower appears to have been erected at about the 
middle of the fifteenth century, and to have been carried out as a 
_distinct work, rather than as a continuation of those last described. 
I am led to this conclusion by the different character of the masonry, 
and, in particular, the fact that oyster-shel/s are employed in forming 
the joints, which is not the case with any other portion of the 
Church. 
I may here mention that since my notice in 1881 of this use of 
oyster-shells being confined to the Perpendicular work at Bishops 
Cannings, referred to in my “ Notes” on that Church in this 
Magazine, I have made many and close observations of this 
peculiarity, which all tend to show that it does not occur (at any 
rate in Wiltshire Churches) in work of earlier date than the middle 
of the fourteenth century. The earliest authenticated instance of 
the use of it with which I am acquainted is that of the well-known 
* Transitional” Church of Edington Monastery, which was dedi- 
cated in 1361. Here oyster-shells are freely employed in both the 
vertical and bed-joints of the masonry in all parts of the building. 
The tower is a beautiful specimen of the best period of Perpen- 
dicular. It is, as will be seen on reference to Plate I., in four 
stages, with angle buttresses carried the full height, and pinnacles 
standing square on them. The pinnacles are richly crocketed and 
pierced, and a pierced parapet of quatrefoils is carried round between 
them. ‘There are three niches of large dimensions on the west 
front, and one each on the north and south, at the second stage. 
All have crocketed canopies, and the four lower ones have the base 
for the figure raised on a low shaft, whilst the upper one is supported 
by a carved angel-corbel. Otherwise the niches only differ in the 
degree of the richness of their groining, those flanking the west 
window are alike in this, and are shown by Fig. 2, Plate II. The 
groining of the one over the window is still richer, while those on 
the north and south faces are treated quite plainly in this respect. 
At the time of the erection of the western tower, the chancel 
appears to have undergone considerable alteration, all the existing 
1 Vol. xxiii., p. 3. 
