Many passages exist, too, referring to the use of Ogam writing on pieces of wood to convey messages by hand. Opinion has been divided as to how far the passages we have quoted bear testimony to the antiquity of Ogam stones for sepulchral purposes. This at least is plain: the belief in this use of the stones existed when the MSS. were written, and the stones themselves furnish strong presumptive evidence that the testimony of the records is based on something more than mere vague tradition. Many of the stones no doubt stand in their original position; but the meagre nature of the inscriptions renders it difficult, if not impossible, to identify them with any degree of certainty with those who figure in ancient Irish records. [Illustration: Ogam Stone (Co. Kerry) in Trinity College, Dublin.] The earliest notice of Ogam writing is in the _Book of Leinster_, which gives the scale of letters. The _Book of Ballymote_ is of especial interest, as it contains a tract on the Ogam writing of the Gaedhil, with the ‘key now ordinarily used in the translations of inscriptions, as well as a variety of ciphers founded on the original characters.’[74] It was not until 1784 that the attention of antiquaries was directly drawn to the existence of Ogam stones by the discovery of the Mount Callan monument in Co. Clare with an inscription in Ogam character. A vigorous controversy raged over this ‘find’; but it had one important result, the interest of archæologists was aroused, and in subsequent years General Vallancey and others gave considerable attention to the subject of Ogams; many stones were discovered and their nature and character investigated, not, however, without many wild theories being advanced, supported by unsound arguments and distorted learning. In 1846 the late Bishop Graves for the first time brought scientific methods to bear on the elucidation of Ogam inscriptions, and clearly demonstrated by independent investigation the certainty of the scale in the _Book of Ballymote_. The general principle upon which he based his analysis was: ‘That in any given language, or group of cognate languages, there is a preference for particular sounds and particular sequence of sounds.’ After various trials he established satisfactory results, and placed the whole scheme of inquiry in papers read before the Royal Irish Academy, in the years 1848–9. ‘The Ogam alphabet,’ says Dr. Graves, ‘consists of lines, or groups of lines, variously arranged with reference to a single stem-line, or to an edge of the substance on which they are traced. The spectator, looking at an upright Ogam monument, will, in general, observe groups of incised strokes of _four_ different kinds: (1) groups of lines to the right; (2) others to the left of the edge; (3) other longer strokes crossing it obliquely; (4) and small notches upon the edge itself.... Ogam inscriptions, in general, begin from the bottom, and read upwards, from left to right. Almost all those which have been