s, when a bell rang to announce a lecture on
Voltaic Electricity by Dr. Bachhoffner; and moving with a stream of people
up a short stair-case, we soon found ourselves in a very commodious and
well-arranged theatre. There are many universities and public institutions
that have not better lecture rooms than this theatre in the Royal
Polytechnic Institution. The lecture was elementary and exceedingly
instructive, pointing out and showing by experiments, the identity between
Magnetism and Electricity--light and heat; but notwithstanding the extreme
perspicuity of the Professor, it was our fate to sit next two old ladies
who seemed to be very incredulous about the whole business.

"If heat and light are the same thing," asked one, "why don't a flame come
out at the spout of a boiling tea-kettle?"

"The steam," answered the other, "may account for that."

"Hush!" cried somebody behind them; and the ladies were silent: but it was
plain they thought Voltaic Electricity had something to do with conjuring,
and that the lecturer might be a professor of Magic. The lecture over, we
returned to the Gallery, where we found the Diving Bell just about to be
put in operation. It is made of cast iron, and weighs three tons; the
interior being provided with seats, and lighted by openings in the crown,
upon which a plate of thick glass is secured. The weighty instrument
suspended by a massive chain to a large swing crane, was soon in motion,
when we observed our skeptical lady-friends join a party and enter, in
order, we presume, to make themselves more sure of the truth of the
diving-bell than they could do of the identity between light and heat. The
bell was soon swung round and lowered into a tank, which holds nearly ten
thousand gallons of water; but we confess our fears for the safety of its
inmates were greatly appeased, when we learned that the whole of this
reservoir of water could be emptied in less than one minute. Slowly and
steadily was the bell drawn up again, and we had the satisfaction of
seeing the enterprising ladies and their companions alight on _terra
firma_, nothing injured excepting that they were greatly flushed in the
face. A man, clad in a water-tight dress and surmounted with a
diving-helmet, next performed a variety of sub-aqueous feats, much to the
amusement and astonishment of the younger part of the audience, one of
whom shouted as he came up above the surface of the water, "Oh! ma'a!
Don't he look like an Ogr