The cook was brimming over with curiosity as to the nature of the surprise which Mr. Peters had in store for them, and Captain Eph confessed that he was "all in the dark"; but, remembering the shape of some of the packages the first assistant brought with him, and his fear lest they should get wet, Sidney believed he could make a very good guess as to what was coming. "He sha'n't be the only one on this 'ere ledge who can rig up a surprise," Uncle Zenas finally said. "You two are to get out of this kitchen, an' stay out until after the light is started; when I call you to supper, come runnin', or I'll make considerable trouble." "This way, Sonny," Captain Eph said with a laugh. "I reckon our place is up-stairs whether they want us to go or not, for there's gettin' to be altogether too much mystery about this 'ere ledge to suit me." Sidney followed the keeper, and when the two were climbing the stairs, the lad said: "This must be one of the highest towers the Government ever built, Captain." "Indeed it isn't, Sonny, not by a long chalk. From the ledge to the light is only one hundred an' twenty feet; but I've got up-stairs an account of the highest tower the Board ever built, an' you shall read it. I ain't tryin' to fill you chock-a-block with facts about light-houses, but when you spring these 'ere questions on me I can't help flashin' up what I know about 'em, which ain't a great deal when you come to simmer it right down." When the two were once more in the watch-room, the keeper handed Sidney a slip of paper on which was printed the following: "The tallest skeleton iron tower erected by the United States Light-House Services was at Hell Gate, Astoria, N. Y., in 1883-84. Its height was two hundred fifty-five feet and five-eighths of an inch. It was built in the form of a frustum of a pyramid, and was fifty-four feet square at the bottom and six feet square at the top. It cost $11,000, and showed nine electric lights, each of which was of six thousand candle power. It was designed to illuminate the narrow, intricate, and dangerous channel as by artificial daylight. At night the effect was grand. The tower itself could not be seen, and the lights appeared as if hung from the heavens. It accomplished all that was intended, and more, for the light was so brilliant that it dazzled the eyes of the pilots, and prevented them from seeing objects beyond the circle illumined. The shadows thrown were so heavy that they took the form of obstacles. So the light was discontinued in 1886, at the instance of those who had obtained its establishment. The tower was sold as it stood, for old iron; but it was so strongly built that dynamite had to be used to accomplish its overthrow." "Captain Eph," Sidney asked as he ceased reading, "what shape is the 'frustum of a pyramid'?"