This building is entirely free from iron. It is approached by stone steps; the door has a pure copper lock, which being opened by a copper key, swings on copper hinges to admit the visitor after he has first cleared the dirt from his shoes upon a copper scraper. Nearly facing the door is a stove to keep up the temperature in cold weather. It looks black enough, and has a black funnel. When the visitor is told that Captain Johnson has his coat-buttons carefully made without any iron shank concealed under their silken cover; and that his assistant, Mr. Brunton, repudiates buttons to his jacket altogether, and has pockets guiltless of a knife; he is apt to turn to the stove, and hint the presence there of the forbidden metal. “Ah, ah!” is the reply, it looks like iron sure enough; but the fireplace, the chimney, the poker, the shovel, are all alike. Nothing but copper, copper, pure copper. This suggests an anecdote. When the operations in this Compass Observatory were first commenced, there was found to be a small variation in the magnet. The instruments were readjusted; their character was investigated, their construction re-examined; other observations were made—but still the variation continued. Pockets were searched for knives; the garden looked over to see that no stray spade or rake had been left outside the building, yet near enough for mischief. Nothing could be discovered. At length the _brass_ bolt on the window was suspected; and though brass had a good character, not being thought capable of coaxing the magnet from its truth, it was, in despair of finding any other delinquent, unscrewed from its position. No sooner was this done, than the wayward needle returned to its true position; the brass bolt was ejected in disgrace, and no morsel of the brazen metal has since been allowed to show itself within the precincts of the building sacred to the mysterious fluid that draws the iron needle to the North.