"I wanted to know about the lens," Sidney replied. "I can't understand why it is any better to have all those glass rings around the light, which make so much work for the cleaners, than it would be if it was one solid globe." "So Cap'n Eph thinks he can explain all that, does he?" Mr. Peters said with a queer gurgle in his throat, much as if he were choking. "Wa'al, all I can say is, if he does, it'll be a good deal more'n I've ever heard of his doin' yet. He'll spin a lot of stuff 'bout bendin' the rays, an' after he gets through you won't know quite as much as you did before." Because he did not understand the meaning of Mr. Peters' remark, Sidney remained silent, and shortly after, the motor having been cleaned thoroughly, he went into the lantern, where he found the keeper awaiting him. Captain Eph had before him several open books, as if he had been refreshing his memory on the subject of lenses, and immediately Sidney appeared, he said, in an apologetic tone: "I don't count on bein' able to give you the idee as to the work of the lenses sich as a man ought'er; but I'll try my best, an' if I fail you won't be any worse off than you are now. In the first place this 'ere is what is known as a light of the first order, meanin' the most powerful in the service, an' the lens alone cost about eight thousand dollars. The middle part of the lens is made up of what's known as 'refractors,' which, 'cordin' to my way of tellin' it, are rings of glass makin' a hollow cylinder six feet in diameter, an' thirty inches high. Below it, as is printed here," and Captain Eph pointed with his thumb to one of the open books, "are six triangular rings of glass, ranged in a cylindrical form, an' above it, a crown of thirteen rings of glass, formin' by their union a hollow cage composed of polished glass, ten feet high, an' six feet in diameter, like this 'ere," and Captain Eph waved his hand toward the brilliant apparatus before them, a picture of which is given here. "But what is the need of making it out of so many pieces?" Sidney asked. "Why wouldn't it be just as well to cover the lamp with a globe, such as is on a house-lamp?"