Rising again into the sunlight, the chemists began an examination of the constitution of the smoke. They were unable to determine its precise character, but they found that its density was astonishingly slight. This accounted for the rapidity with which it had risen, and the great height which it had attained in the comparatively light atmosphere of Mars.
"It is evident," said one of the chemists, "that this smoke does not extend down to the surface of the planet. From what the astronomers say as to the density of the air on Mars, it is probable that a clear space of at least a mile in height exists between the surface of Mars and the lower limit of the smoke curtain. Just how deep the latter is we can only determine by experiment, but it would not be surprising if the thickness of this great blanket which Mars has thrown around itself should prove to be a quarter or half a mile."
"Anyhow," said one of the United States army officers, "they have dodged out of sight, and I don't see why we should not dodge in and get at them. If there is clear air under the smoke, as you think, why couldn't the ships dart down through the curtain and come to a close tackle with the Martians?"
"It would not do at all," said the commander. "We might simply run ourselves into an ambush. No; we must stay outside, and if possible fight them from here."
"They can't keep this thing up forever," said the officer. "Perhaps the smoke will clear off after a while, and then we will have a chance."
"Not much hope of that, I am afraid," said the chemist who had originally spoken. "This smoke could remain floating in the atmosphere for weeks, and the only wonder to me is how they ever expect to get rid of it, when they think their enemies have gone and they want some sunshine again."
"All that is mere speculation," said Mr. Edison; "let us get at something practical. We must do one of two things; either attack them shielded as they are, or wait until the smoke has cleared away. The only other alternative, that of plunging blindly down through the curtain is at present not to be thought of."
"I am afraid we couldn't stand a very long siege ourselves," suddenly remarked the chief commissary of the expedition, who was one of the members of the flagship's company.
"What do you mean by that?" asked Mr. Edison sharply, turning to him.
"Well, sir, you see," said the commissary, stammering, "our provisions wouldn't hold out."