{And when he opened} (kai hotan (886e)oixen). Here modal an
is used with hote (used about the opening of the preceding six
seals), but hotan is not here rendered more indefinite, as is
sometimes true ( Mr 3:11  Re 4:9 ), but here and possibly (can be
repetition) in  Mr 11:19  it is a particular instance, not a
general rule (Robertson, _Grammar_, p. 973). {There followed a
silence} (egeneto sig(885c)). Second aorist middle of ginomai.
"There came silence." Dramatic effect by this profound stillness
with no elder or angel speaking, no chorus of praise nor cry of
adoration, no thunder from the throne (Swete), but a temporary
cessation in the revelations. See  10:4 . {About the space of
half an hour} (h(9373) h(886d)i(9372)on). Late and rare word (h(886d)i, half,
h(9372)a, hour), here only in N.T. Accusative of extent of time.