thirty minutes past
four o'clock
The sergeant was so hot-headed in his determination to stand by the fort , that it required violence to remove him ; and it was not until twenty minutes past four that the Syndicate observers perceived that he had been taken to the hill behind which the garrison was encamped . As it had been decided that Repeller No. 2 should discharge the next instantaneous motor-bomb , there was an anxious desire on the part of the operators on that vessel that in this , their first experience , they might do their duty as well as their comrades on board the other repeller had done theirs . The most accurate observations , the most careful calculations , were made and re-made , the point to be aimed at being about the centre of the fort . The motor-bomb had been in the cannon for nearly an hour , and everything had long been ready , when at precisely thirty minutes past four o'clock the signal to discharge came from the Director-in-chief ; and in four seconds afterwards the index on the scale indicated that the gun was in the proper position , and the button was touched . The motor-bomb was set to act the instant it should touch any portion of the fort , and the effect was different from that of the other bombs . There was a quick , hard shock , but it was all in the air . Thousands of panes of glass in the city and in houses for miles around were cracked or broken , birds fell dead or stunned upon the ground , and people on elevations at considerable distances felt as if they had received a blow ; but there was no trembling of the ground .