Bible Dictionary and Topical Bible  (Easton's, Nave's, Torrey's):

¹Α, the first letter in almost all alphabets. In Hebrew, it is called Aleph, א, which signifies ox, from the shape of it in the old Phenician alphabet, where it somewhat resembles the head and horns of that animal. (Plutarch, Quest. Sympos. ix:2; Gesenius Hebrew Thesaurus p. 1.) This Hebrew name has passed over, along with the letter itself, into the Greek Alpha. Both the Hebrews, and Greeks employed the letters of their alphabets as numerals; and Α, (Aleph or Alpha) therefore, denoted one, the first. Hence our Lord says of himself, that he is Alpha and Omega, i. e., the first and the last, the beginning and the ending, as he himself explains it (Revelation 1:8, 11; 21:6; 22:13). This expression in the Old Testament was employed to denote the eternity of God (Isaiah 44:6). The Church very early adopted these two letters as a symbol of the eternal divinity of our Lord, and used it extensively on monuments of every description, sometimes alone, but more frequently in connection with the cross and the monogram of Christ, in its various forms, as follows:

²The use of a or an before a word, which began with vocal h varied at the date of the Authorized Version (Α. D. 1611). Thus we find a half in Exodus 25:10, but an half in Daniel 12:7; a harp in I Chrοnicles 25:3, but an harp in I Samuel 16:16; a hammer in Jeremiah 23:29, but an hammer in Judges 4:21 (see also Genesis 27:11; II Kings 1.8; II Kings 12:9, and Exodus 28 :32) . An is sometimes abbreviated to a and appears to have been closely related to on - "Fell a sleep" Acts 7:6o), "fell on sleep" (Acts 13:36). In Εxοdus 19:18, "Mount Sinai was altogether on α smoke," means all Mount Sinai smoked. In II Chron. 2:18, ."To set the people a work," means to set them to work. "Α work" should be written with a hyphen (a-work), "Sets it a-work."-Shakespeaτe.