The next great element which aided in producing tracery windows was the wheel, or other richly-pierced circular window. This, again, originated under the Romanesque style, as we may see at Barfreston and elsewhere. It is, in fact, a very close approach to tracery, and when placed in the space between comprising and comprised arches, it almost completes the change. All that is wanted is the piercing of the intervening spaces in forms whose outlines are parallel to the main piercings, so as to form what Professor Willis calls _bar_ tracery. This was, I fancy, commenced in France--though there are very early traces of it in England--and was done at first in a partial and clumsy manner, as in some windows at Le Mans and Tours, but soon was systematised. I do not see that in any of the previous steps the French were in advance of the English architects, but in this last step I think they were so, and this led them to a much earlier abandonment of the single window and its combinations; so that for some time the French were using tracery windows, while we were rendering more perfect the unmullioned system--not from want of knowledge of the other, but rather from a preference for a system in which we were producing more beautiful combinations than our neighbours had attained. It is not a very profitable question to inquire by how many years the French may have been in advance of us in this development, and it is so exceedingly difficult to get at positive dates of the erection of buildings in either country, that it would be impossible if desired. The fact, no doubt, is, that for many years the two kinds of window were contemporaneous. Thus, traceried windows may have been in use at Rheims and Amiens, while the older kind was being used at Bourges and Chartres. It is said that in England the fully-developed bar tracery was first used in Westminster Abbey, which was commenced in 1245; but this is merely an assumption; and it is clear that it was used in the eastern part of St. Paul’s, a part of which was consecrated in 1240. The east window of Netley Abbey looks very early, but I do not know its real date, but believe it is said to have been finished in 1249; while the eastern windows at Lincoln look too thoroughly developed to be very early specimens, though known to have been erected between 1256 and 1280. In any case the change had fully established itself in England during the third quarter of the century.[40]