"There's no doubt," remarked Morton, "that what we have just seen are relics of an ancient people, but what I can't understand is, why, if they were civilized enough to wear dresses, and to have a developed religious belief—savage as it was—" ("No worse than the Carthagenians," interjected Brown), "to know how to obtain iron and temper it, that they did not build permanent buildings, the ruins of which would remain?"
"Mud, my dear fellow, mud," replied Brown. "Remember the nations who have disappeared off the face of America, and can only be traced by their pottery and burial mounds. Why, the gorgeous cities of ancient Mexico were built of mud bricks, which go back to their mother earth, once the domiciles they form are abandoned."
"But their smelting-works for manufacturing iron?"
"There you have me. But we must try and find that knife; perhaps they buried it with Stuart."
"Billy got something from one of the old men, but I don't know what it was," said Charlie.
"Billy! What old man bin give it?" asked Morton.
Billy grinned, and produced from the inside of his shirt the knife mentioned in the journal. It was a curious-looking blade about a foot long, broad and somewhat curved. Even after the work Stuart had done with it in carving on the rocks, it was as sharp as an ordinary knife.
"That's a Malay weapon," said Brown, after examination. "Whoever our ancient Australians were they came from the north. I suppose we must wait until we get the writing deciphered, if there is a man clever enough to do it."
Looking closer, they found that the blade had the mysterious triangle engraved on it. This constantly recurring symbol led to much speculation as to whether they were not an offshoot of Freemasons, who in some remote time had wandered into central Australia; but as Charlie ingenuously reminded them that these fellows had not built anything, the theory had to be discarded.
"What's to be done next?" said Morton. "I'm for going to find Hentig's grave, if possible, and recovering the papers buried there."