One day, to the surprise of the bookseller, he coveted a volume on the discoveries of Volta in electricity, but not having the price, he saved his pennies and secured the volume. It was written in French, and so he was obliged to save again, until he could buy a dictionary. Then he began to read the volume, and, with the help of his elder brother, William, to repeat the experiments described in it, with a home-made battery, in the scullery behind his father's house. In constructing the battery, the boy philosophers ran short of money to procure the requisite copper-plates. They had only a few copper coins left. A happy thought occurred to Charles, who was the leading spirit in these researches, 'We must use the pennies themselves,' said he, and the battery was soon complete.