[425] Dr. J. Anderson’s _Scotland in Early Christian Times_, 2nd ser., p. 2. [426] _Ibid._, p. 7. [427] _Ibid._, p. 21. [428] Rev. J. P. Mahaffy’s _Book of Trinity College_. [429] _Archælogia_, vol. xliii., p. 131. [430] Sir W. Wilde’s _Catal. Mus. R.I.A._, p. 284. CHAPTER VII CELTIC ART OF THE CHRISTIAN PERIOD TECHNICAL PROCESSES AND MATERIALS EMPLOYED DURING THE CHRISTIAN CELTIC PERIOD IN GREAT BRITAIN Ecclesiastical and other MSS. written on sheets of vellum and bound up in the form of a book were introduced into this country with Christianity. The materials and tools used by the Celtic scribes and illuminators probably did not differ to any great extent from those used throughout Europe during the Middle Ages. The parchment of the Irish MSS. is, however, generally much thicker[431] than that of the Carlovingian and other foreign MSS. The letters in the Irish MSS. of the best period, such as the Book of Kells, are composed partly of extremely fine lines, drawn with a firm hand, which gradually expand in width to form the other parts of the letters. These could hardly have been made with a reed or a brush, so that it is probable that the pens of the Irish scribes were made from the quills of swans, geese, crows, and other birds. The black ink used in the Irish MSS. is remarkable for its blackness and durability; and Bede, the historian, speaks highly in praise of the colours prepared in Ireland, and especially of the brilliancy and permanence of the red made from whelks.[432] Some colours, such as yellow, are put on thin and transparent; whilst others, such as red, have a thick body made of titurated earth or other skilfully prepared material, mixed with some strong binding material of the nature of gum or varnish.[433] [431] Sir E. M. Thompson’s _Greek and Latin Palæography_, p. 38. [432] Bede’s _Eccl. Hist_., bk. i., chap. 1. [433] Dr. Ferdinand Keller in the _Ulster Journal of Archæology_, vol. viii. The material employed for the highly ornamented sculptured monuments of the Christian Celtic period was generally that most readily procurable on the spot, but a preference was always shown for a freestone, which could be easily worked. The greater proportion of the best crosses are carved in a fine-grained sandstone. In Cornwall granite was most generally used, although Polyphant stone was also used. In the Isle of Man nearly all the crosses are of slate. Hard, volcanic rocks were avoided where possible on account of the difficulty of working. There are, however, crosses of trap-rock at Carew, Pembrokeshire, and Moel Siarman, Brecknockshire.