The various plaits have been worked out by Mr. A. G. Langdon in his admirable study of the Cornish crosses. At a meeting of the British Association he exhibited a hundred drawings of different crosses, etc., illustrative of a paper read by Mr. J. Romilly Allen on "The Early Christian Monuments of Cornwall." When some incredulity was expressed as to there being so many examples in that county, Mr. Langdon explained that not only did all these come from Cornwall, but that the examples brought before the Association represented only about one-third of the whole number known to exist. And since that date a good many more have been noticed. The variety in design of the crosses is very great indeed. Some affect the Greek cross, some the Latin; some are with a figure on them, some plain, others richly ornamented. But what is remarkable about them is, in the first place, they are nearly all in granite, a material in which nothing was done from the seventh century down to the fifteenth, as though the capability of working such a hard intractable stone had been lost. And, in the second place, the ornamentation is in the lost art of plaiting, of the beauty and difficulty of which we can hardly conceive till we attempt it. There is first the four-string plait, then that with six, and lastly that with eight. Then three strings are combined together in each plait, then split, forming the so-called Stafford knot; the knot and the plait are worked together; now a loop is dropped, forming a bold and pleasing interruption in the pattern. Then a ring is introduced and plaited into the pattern; then chain-work is introduced; in fact, an endless variety is formed, exercising the ingenuity of the artist to the uttermost. It would be an excellent amusement and occupation for a rainy day in an hotel for the tourist to set to work upon and unravel the mysteries of these Celtic knots. The old interlaced work, or the tradition of it, seems to have lingered on in the glazing of windows, and some very beautiful examples remain in England and in France. Mr. Romilly Allen points out:-- "In Egyptian, Greek, and Roman decorative art the only kind of interlaced work is the plait, without any modification whatever; and the man who discovered how to devise new patterns from a simple plait, by making what I term _breaks_, laid the foundation of all the wonderfully complicated and truly bewildering forms of interlaced ornament found on such a masterpiece of the art of illumination as the _Book of Kells_. Although we do not know _who_ made the discovery of how to make breaks in a plait, we know pretty nearly _when_ it was made."[4]