Sam proceeded, and soon again forgot herself in a fixed and earnest gaze.
"The two telegraph instruments communicating with India and America, which stood on two tables, side by side, in Mr. Pender's house, were supplied by two batteries in the basement of the building. Eighty cells of Daniel's battery were used upon the Penzance circuit for India, and 100 cells on the Brest circuit for America. The ordinary water-pipes of the house served to connect the batteries with the earth, so as to enable them to pump their electricity from that inexhaustible reservoir."
"I was not aware that electricity had to be pumped up through pipes like water," interrupted Mrs. Wright, on whose mild countenance a complication of puzzled expressions was gradually gathering.
"It is not so pumped up," said Sam. "The pipes were used, not because they were pipes, but because they were metal, and therefore good conductors."
"But you haven't told us about the beautiful experiments yet," murmured Letta, a little impatiently.
"I 'm coming to them, little one," said Sam. "One battery exhibited the power as well as the beauty of that mysterious force which we call electricity. It was the large Grove battery. A current passed from it to copper wires, in a certain manner, produced a dazzling green light, and the
