our tram-cars and locomotives with railway speed, minus railway smoke and fuss. He is a very giant in the chemist's laboratory, and, above all, a swift messenger to carry the world's news. Even when out and raging to and fro in a wild state, more than half-disposed to rend our mansions, and split our steeples, and wreck our ships, we have only to provide him with a tiny metal stair-case, down which he will instantly glide from the upper regions to the earth without noise or damage. Shakespeare never imagined, and Mercury never accomplished, the speed at which he travels; and he will not only carry our news or express our sentiments and wishes far and wide over the land, but he will rush with them, over rock, sand, mud, and ooze, along the bottom of the deep deep sea!
And this brings us to a point. Some of the master minds before mentioned, having conceived the idea that telegraphic communication might be carried on under water, set about experimenting. Between the years 1839 and 1851 enterprising men in the Old World and the New suggested, pondered, planned, and placed wires under water, along which our Spark ran more or less successfully.
One of the difficulties of these experiments consisted in this, that, while the Spark runs readily along one class of substances, he cannot, or will not, run along others. Substances of the first class, com-
