"Where?" inquired the colored man, thrusting his head farther into the room, and opening his eyes to their fullest extent. "Ef it ain't violatin' no confidences, Massa Jack, would yo' jest kindly mention it to yo's truly," and Professor Henderson's faithful servant, who had followed him into many dangers, looked at the two boys, who, of late years, had shared the labors of the well-known scientist. "Where am dose diamonds, Massa Jack?" "On the moon," was the answer. "On de moon? Ha! Ha! Dat's a joke!" And Washington began to laugh. "On de moon! Ha! Ho!" "Well, you can read it for yourself," went on the lad, tossing the paper over to the colored man. The latter picked it up, gazed at it, first from one side, and then from the other. Next he turned it upside down, but, as this did not make the article any clearer, he turned the paper back again. Then he remarked, with a puzzled air: "Well, I neber could read without mah glasses, Massa Jack, so I guess I'll hab t' let it go until annoder time. Diamonds on de moon, eh? Dat's wonderful! I wonder what dey'll be doin' next? But I'se got t' go. Diamonds on de moon, eh? Diamonds on de moon!" As Washington turned to leave the room, for he had entered it when Jack and Mark were talking to aim, the latter lad asked: "Did you want to see us about anything particular, Wash?" "Why, I suah did," was the reply, "I did come t' tell yo' dat Perfesser Henderson would be pleased to hold some conversations wid yo', but when Massa Jack done mentioned about dem diamonds, I clean fo'got it. Diamonds on de moon, eh?" "Well, if the professor wants us we'd better go," suggested Mark. "Come on, Jack, and stop dreaming about Reonaris and the moonbeams. Get back to earth." "All right; laugh if you want to," said Jack sturdily, "but the time will come, Mark, when you'll find out that I'm right." "How?" asked Mark. "I don't know, but I'm sure I can prove what I say." The two boys were to have the wonderful diamond story demonstrated to them sooner than either expected. Following the colored man, the lads, Jack carrying the paper, made their way to the laboratory of Professor Henderson. His door was open, and the aged man, whose hair and beard were now white with age, was bending over a table covered with papers, chemical apparatus, test tubes, alembecs, Bunsen burners, globes, and various pieces of apparatus. Another man, not quite so old as was Mr. Henderson, was on the point of leaving the apartment. "Ah, boys," remarked the older professor, as he caught sight of them, "I hope I didn't disturb you by sending for you." "No; Jack and I were only having a red-hot discussion about diamonds on the moon," said Mark, with a laugh. "Diamonds on the moon!" exclaimed Professor Henderson. "Diamonds on the moon?" repeated his friend, Prof. Santell Roumann. "Is this a joke, boys?"