The curious Ogam alphabet, which may date from the fifth century A.D., and the use of which did not extend outside the British Isles, is held by some scholars to be derived from the Runic, but its characters indicate that more probably it is a debased copy of the Roman. Ogam, according to Professor Rhys, the highest authority on the subject, probably means "skilled use of words." The letters are formed by straight or slanting strokes drawn above, or beneath, or right through horizontal or perpendicular lines. The alphabet is divided into four aicmes or groups, each containing five letters: the first aicme, B, L, F, S, N being placed under the line (assuming this to be horizontal); the second aicme, H, T, D, C, Qn, above it; the third aicme, M, G, Ng, F(?) R, diagonally through it; and the fourth aicme, comprising the vowels A, O, U, E, I, intersecting it at right angles. Canon Taylor sees in the ogams an adaptation of the runes to the needs of the engraver, "notches cut with a knife on the edge of a squared staff being substituted for the ordinary runes." And he thinks that the derivation of the ogams from runes is shown in the fact that their names agree with the names of runes of corresponding value, and that they are found exclusively in regions where Scandinavian settlements were established. Professor Rhys regards them as "probably, the work of a grammarian acquainted with Roman writing, but too proud to adopt it." The larger number of Ogam inscriptions occur in Ireland; others are scattered over Scotland, Wales, and the south-west of England. It may be thought that any survey of the history of the Alphabet, however free from overcrowding in detail, and however popular in treatment, would outline the story of the origin of, and changes in, each of the twenty-six letters which are, for the English-speaking races, the vehicle of communication and the depository of knowledge. But, probably, enough has been said to show that the information which would alone warrant such table of derivations is not yet forthcoming, and, perhaps, never will be. The most plausible theory that the wit of man, supported by a set of facts that seemed to hang well together, could devise, was formulated by M. de Rougé, and it has been seen that the epigraphic material found in the Ægean renders his apparently well-based and coherent theory no longer tenable.