“Well,” he replied, “it’s stood every test I’ve made upon it. Beyond doubt it’s the same article that’s so scarce on our side. I held out for steel, but the durability of gold was pointed out, and it was explained the _Propellier_ would be in the museum for all time, and gold was the metal. I wouldn’t argue with them. They are going to publish books with exquisite illustrations, the date and details of when Potolili first sighted us and the car. Little guide books will be issued, explaining all about the strange little steel car and gold _Propellier_, presented to the people of Centauri by the renowned Professor Saxlehner. ‘Renowned Saxlehner’ sounds first rate—ahem! Now look at this.” He opened a small box stuffed with silk floss and took out a huge diamond the size and shape of a pecan and of dazzling brilliancy. “For the _Propellier_” he explained; “a perfect gem without a flaw, yet not genuine. Yes, Virgillius, the Centaurians have discovered the secret; this stone is as perfect as any ever taken from the mines. Before returning home I shall master the intricate combination of gold blocks and diamonds. Nearly all the genuine gems of Centauri have been placed in the museum. The manufactured article is the standard; man’s ingenuity is rated invaluable. Notice the ruby, it contains a fire never seen in the most famous gems of our world; but the stone that defies penetration is the emerald. It guards its secret well and is very rare. Many have attempted to produce the stone and turned out fairly good imitations, but imitation was failure, a perfect emerald must be produced. Half a century ago a noted scientist delved into the mystery of the emerald. In his efforts to get ahead of competitors he experimented upon the sacred emerald loaned to him from the museum and actually reduced it to liquid. Old Centauri was sent for and found the scientist frantically trying to analyze the liquid, under the impression it would shortly petrify again, but, to the amazement of both, the strange greenish liquid dwindled and evaporated—that ended the emerald problem with the scientist. He succumbed to an ailment unknown to physicians, and it is believed he inhaled the emerald. Scientists declare the fatal incident analyzed the emerald. The gem is composed of congealed poisonous gases petrified. The emerald man became famous because he came nearer solving the green mystery, but his secret died with him. When pressed to divulge he replied: ‘My experiment failed; had I produced the perfect stone the knowledge would have been free to all. I produced nothing and lost the emerald, as I feared I would. Failures are enervating, should remain obscure; the time in this sphere is too short to ponder over them.’”