Once more the Lucifer swept over the burning building. Down shot the remaining grenades, falling into the mass of flames and bursting, though the reports could not be heard because of the tumult in the streets below. For the firemen and spectators had seen the sudden dying down of the fire, they had caught sight of a shadowy shape in the night, hovering over the blazing building, and they wondered what it all meant.
"How is it?" asked Tom, as he guided the craft back to get a view of his work.
"That settles it!" answered Ned. "There isn't fire enough now to broil a beefsteak!"
This was not exactly true, for the blaze was not entirely subdued. But the flames had all been killed off in the higher parts of the Landmark Building, and what remained could easily be dealt with by the firemen on the ground. They proceeded to make short work of the remainder of the conflagration, the while wondering who had so effectively aided them from the clouds.
"Well," observed Tom, as he saw how effectively he had smothered the great fire, "it's of no use to go on now. I haven't an ounce of chemical left on board. I can't give the demonstration that I planned for tomorrow."
"You've given a better demonstration here than you ever could have in the other city," declared Mr. Baxter. "I fancy this will be all the test needed, Tom Swift!"
"Perhaps. I hope so. But we may as well land and see from the ground the effect of our work. I'd also like to inquire if any one was hurt. Let's go down."
It was rather ticklish work, making a landing in the midst of a populous city, and at night. But as it happened, there had been a number of buildings razed in the vicinity of the Landmark structure, and there was a large, vacant level space. Also several of the city's fire department searchlights were focused around the burning structure, and when it became evident that an airship was going to land—though as yet none guessed whose it was—the searchlights were turned on the vacant spot and Tom was able to make a good landing, his own powerful searchlight giving effective aid.
"What did you do that put out the fire?" demanded the chief of the Newmarket department, as he rushed up with a crowd of others when Tom and his friends alighted.
"I dropped a few grenades down that chimney," modestly answered the young inventor.