OBS. 2.—­Letters written for numbers, after the manner of the Romans, though read as words, are never words in themselves; nor are they, except perhaps in one or two instances, abbreviations of words.  C, a hundred, comes probably from Centum; and M, a thousand, is the first letter of Mille; but the others, I, V, X, L, D, and the various combinations of them all, are direct numerical signs, as are the Arabic figures.  Hence it is not really necessary that the period should be set after them, except at the end of a sentence, or where it is suitable as a sign of pause.  It is, however, and always has been, a prevalent custom, to mark numbers of this kind with a period, as if they were abbreviations; as, “While pope Sixtus V. who succeeded Gregory XIII. fulminated the thunder of the church against the king of Navarre.”—­Smollet’s Eng., iii, 82.  The period is here inserted where the reading requires only the comma; and, in my opinion, the latter point should have been preferred.  Sometimes, of late, we find other points set after this period; as, “Otho II., surnamed the Bloody, was son and successor of Otho I.; he died in 983.”—­Univ.  Biog.  Dict. This may be an improvement on the former practice, but double points are not generally used, even where they are proper; and, if the period is not indispensable, a simple change of the point would perhaps sooner gain the sanction of general usage.

OBS. 3.—­Some writers, judging the period to be wrong or needless in such cases, omit it, and insert only such points as the reading requires; as, “For want of doing this, Judge Blackstone has, in Book IV, Chap. 17, committed some most ludicrous errors.”—­Cobbett’s Gram., Let.  XIX, 251.  To insert points needlessly, is as bad a fault as to omit them when they are requisite.  In Wm. Day’s “Punctuation Reduced to a System,” (London, 1847,) we have the following obscure and questionable RULE:  “Besides denoting a grammatical pause, the full point is used to mark contractions, and is requisite after every abbreviated word, as well as after numeral letters.”—­Page 102.  This seems to suggest that both a pause and a contraction may be denoted by the same point.  But what are properly called “contractions,” are marked not by the period, but by the apostrophe, which is no sign of pause; and the confounding of these with words “abbreviated,” makes this rule utterly absurd.  As for the period “after numeral letters,” if they really needed it at all, they would need it severally, as do the abbreviations; but there are none of them, which do not uniformly dispense with it, when not final to the number; and they may as well dispense with it, in like manner, whenever they are not final to the sentence.