TERRESTRIAL MAGNETISM.
[Footnote: For a full account of experiments relating to magnetism on railways in New York city, see SCIENTIFIC AMERICAN, January 19,1884.]
To the Editor of the Scientific American:
An item has appeared recently in several papers, stating that New York is a highly magnetized city--that the elevated railroad, Brooklyn Bridge cables, etc., are all highly magnetized. As this might convey to the general reader the impression that the magnetism thus exhibited was peculiar to New York city, and as many of your subscribers look anxiously for your answers to numerous questions put for the elucidation of apparent, scientific mysteries, I have thought that perhaps a statement in plain language of experiments made at various times, to elucidate this subject, might, in conjunction with a diagram, serve to explain even to those who have not made a special study of science a few of the interesting phenomena connected with