book-stall in the vicinity of Pall Mall, which was then a dilapidated
and unpaved thoroughfare. Most of his pocket-money was spent in
purchasing the books which had taken his fancy, whether fairy tales,
history, or science. 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, till 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.

In September, 1821, Wheatstone brought himself into public notice by
exhibiting the 'Enchanted Lyre,' or 'Aconcryptophone,' at a music-shop
at Pall Mall and in the Adelaide Gallery. It consisted of a mimic lyre
hung from the ceiling by a cord, and emitting the strains of several
instruments--the piano, harp, and dulcimer. In reality it was a mere
sounding box, and the cord was a steel rod that conveyed the vibrations
of the music from the several instruments which were played out of sight
and ear-shot. At this period Wheatstone made numerous experiments on
sound and its transmission. Some of his results are preserved in
Thomson's ANNALS OF PHILOSOPHY for 1823. He recognised that sound is
propagated by waves or oscillations of the atmosphere, as light by
undulations of the luminiferous ether. Water, and solid bodies, such as
glass, or metal, or sonorous wood, convey the modulations with high
velocity, and he conceived the plan of transmitting sound-signals,