A hundred and forty and four cubits (εκατον τεσσερακοντα τεσσαρων πηχων). Another multiple Rev 12 (12x12=144) as in Revelation 7:4; Revelation 14:1. It is not clear whether it is the height or the breadth of the wall that is meant, though υψος (height) comes just before. That would be 216 feet high (cf. verse Revelation 21:12), not enormous in comparison with the 7,000,000 feet (1500 miles) height of the city.

According to the measure of a man, that is, of an angel (μετρον ανθρωπου, ο εστιν αγγελου). No preposition for "according to," just the accusative case of general reference in apposition with the verb εμετρησεν. Though measured by an angel, a human standard was employed, man's measure which is angel's (Bengel).

Rev 21:18

The building of the wall (η ενδωμησις του τειχους). Or ενδομησις, elsewhere so far only in Josephus (Ant. XV. 9. 6, a mole or breakwater) and in an inscription (Syll. 583 31), apparently from ενδομεω, to build in, and so the fact of building in. The wall had jasper (verse Revelation 21:11) built into it.

Was pure gold (χρυσιον καθαρον). No copula ην (was) expressed. The city shone like a mass of gold in contrast with the jasper lustre of the wall.

Pure glass (υαλω καθαρω). Associative instrumental case after ομοιον. Hυαλος (apparently from υε, it rains, and so raindrop) in N.T. only Revelation 21:18; Revelation 21:21.