How was a glyphic comparison of the phonic symbols of both languages made in substantiation of the oral comparison?

By juxtaposition. On the penultimate blank page of a book of inferior literary style, entituled Sweets of Sin (produced by Bloom and so manipulated that its front cover came in contact with the surface of the table) with a pencil (supplied by Stephen) Stephen wrote the Irish characters for gee, eh, dee, em, simple and modified, and Bloom in turn wrote the Hebrew characters ghimel, aleph, daleth and (in the absence of mem) a substituted qoph, explaining their arithmetical values as ordinal and cardinal numbers, videlicet 3, 1, 4, and 100.

Was the knowledge possessed by both of each of these languages, the extinct and the revived, theoretical or practical?