about 1 p.m.
Sometimes , as we have said , all nature seemed to be steeped in thick darkness , at other times the fires of the volcano blazed upward , spreading a red glare on the rolling clouds and over the heaving sea . Lightning also played its part as well as thunder , but the latter was scarcely distinguishable from the volcano 's roar . Three days before Sunday the 26th of August , Captain Roy -- as well as the crews of several other vessels that were in Sunda Straits at the time -- had observed a marked though gradual increase in the violence of the eruption . On that day , as we read in the _ Report of the Krakatoa Committee of the Royal Society _ , about 1 p.m. the detonations caused by the explosive action attained such violence as to be heard at Batavia , about 100 English miles away . At 2 p.m. of the same day , Captain Thompson of the _ Medea _ , when about 76 miles east-north-east of the island , saw a black mass rising like clouds of smoke to a height which has been estimated at no less than 17 miles ! And the detonations were at that time taking place at intervals of ten minutes . But , terrible though these explosions must have been , they were but as the whisperings of the volcano .