The box of which Mr. Hardy spoke was a long case, which had never been opened since their arrival. No entreaties of his children could induce Mr. Hardy to say what were its contents, and the young ones had often wondered and puzzled over what they could be. It had come, therefore, to be known in the family as the mysterious box. With greatly excited curiosity the boys now walked toward the house; but there was a slight delay, for as they approached Maud and Ethel came running to meet them. "Is anything the matter with the dam, papa? We have been watching you having such a long talk with the boys. What is it all about?" Mr. Hardy now told them as much as he thought proper of the state of things, and gave them their instructions. The girls, who had no idea there was any real danger, and who had besides an unlimited confidence in their father and brothers, were disposed to look upon It as fun, and Mr. Hardy had to speak quite seriously to be sure that his orders would be strictly attended to. The boys then informed them that the mysterious box was to be opened, and the whole party went up to the house. The box had been placed in the storeroom on the upper floor of the tower, and the boys took up screwdrivers and hammers to open it. The latter tools were not necessary, as the case was very carefully screwed up; and when the top was taken off it was found that there was an inside case of tin soldered up. As the boys were cutting through this they expressed their opinion that, from the extreme care taken, the contents must be very valuable. Still Mr. Hardy would give no clew; and when the case was finally opened, the astonishment of all was unbounded to find that it contained four dozen large rockets and a dozen blue-lights. One dozen of these rockets were ordinary signal rockets, but the rest were covered with strong tin cases. "Fireworks!" they all exclaimed in intense surprise. "What have you brought fireworks all this way for, papa?"