It was a thrilling sight, and one the two chums would not have missed for a great deal. The lone Zeppelin was steering directly over a part of the city which was densely populated by the poor. Doubtless other great airships were moving in lanes that would take them over outlying districts. The fleet had evidently separated on nearing the city, thus minimizing the risk of being brought down by volleys or shrapnel, or the efforts of airplane defenders who were already rising to give battle to the German monsters.

“There, they dropped something, for I could see what looked like a spark falling!” exclaimed Tom suddenly.

“That was a fire bomb,” said a man standing near, who probably had passed through a number of similar attacks, and was well posted. “It is filled with combustible fluid, and on bursting sets fire to everything around.”

Hardly had he spoken when they heard a terrific report. At the same instant there was a vivid flash, as of fire. The boys were reminded of lightning on a black night; but in this case the glare stayed, as though the fire had accomplished the work intended.

Quickly following there came another frightful smash.

“That was a regular bomb!” cried the man close to Tom. “Chances are it’s done considerable damage, for it must have dropped in one of the congested districts.”

“But there are no fortifications inside London, are there?” asked Jack, horrified at the thought of death and destruction being scattered among just such a crowd as had gathered in the streets around them.

“Oh! that’s all tommyrot,” explained the man, with a hoarse laugh. “They make out London is a regular fortified city and that they are smashing docks and sinking munition-laden steamers, as well as blowing up barracks. All they do is to murder half a hundred poor women and children and burn some of the crowded tenements. But just wait, the time will come when we’ll get our revenge on Berlin!”

A second Zeppelin was discovered sailing along. The crash of bursting bombs became almost continuous, as though those above were trying to empty their reservoirs while passing over the capital that seemed to be the particular object of German hatred.

Carried along with the crowd, eager to see with their own eyes some of the exciting scenes, the two American lads found themselves in a more squalid section of the city. No doubt this was a part of what was known as the slums.