Page:Popular Science Monthly Volume 12.djvu/471

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THE MAGNETIC OBSERVATORY AT MADISON.

The engine was actually set up in the boat, but at a low stage of the river, and no trial could be made until the river should again rise, some months later. Having no funds to carry them through so long a period, Evans's agents were induced to remove the engine again, and to set it up in a saw-mill, where it created great astonishment by its extraordinary performance in sawing lumber.

 

THE MAGNETIC OBSERVATORY AT MADISON, WISCONSIN.
By E. W. DAVIS.

A VISITOR to the grounds of the State University at Madison, Wisconsin, might perhaps wonder what could be the use of three small chimneys to be seen standing out of the south side of the university hill. On being told that under the ground is one of the two magnetic observatories of this country, he may be curious to see more. If so, he will go on down some distance past the chimneys, and, turning into a moderately deep cut, will enter the observatory through a tunnel in the hill-side.

Having divested himself of whatever iron he may have about him—his keys, his knife, and even his watch—two doors are successively thrown open, and he is ushered into a low, vaulted chamber measuring seventeen feet square. The darkness, which would be absolute but for the faint gleams of light escaping through the close coverings of three lamps; the silence, broken only by the ticking of two clocks, or the tread upon the paved floor; the strange character of the instruments, which he begins dimly to see—all unite to create a feeling of oppression, as though one breathed the air of some sorcerer's den.

Though the visitor may be interested in what there is to be seen, yet, in the short time he is allowed to stay, he can get but an imperfect idea of it all. He will learn, it may be, the names of the several instruments, and gain a slight knowledge of the manner in which the observations are recorded. He will be told that the observatory was established at Madison in the autumn of 1876 by the United States Coast Survey; and also, perhaps, that the instruments employed were in use at Key West, Florida, and then at Washington, D. C, being moved from the latter place in order not to be so nearly upon the meridian of a magnetic observatory at Quebec, Canada. If desired, the person in charge will show him some of the traces, one of these being nothing more than the crooked path which a moving spot of light, reflected from a mirror attached to either of the magnets, has left upon sensitive paper.