invention of electric telegraphy by Wheatstone and others, and to the
great manufactures of telegraph cables and telegraph wire, and of the
materials required for them. The value of the cargo of the Great
Eastern alone in the recent Bombay telegraph expedition was
calculated at three millions of pounds sterling. It also led to the
employment of thousands of operators to transmit the telegraphic
messages, and to a great increase of our commerce in nearly all its
branches by the more rapid means of communication. The discovery of
Voltaic electricity further led to the invention of electro-plating,
and to the employment of a large number of persons in that business.
The numerous experimental researches on specific heat, latent heat,
the tension of vapours, the properties of water, the mechanical
effect of heat, etc., resulted in the development of steam-engines,
and railways, and the almost endless employments depending upon their
construction and use. About a quarter of a million of persons are
employed on railways alone in Great Britain. The various original
investigations on the chemical effects of light led to the invention
of photography, and have given employment to thousands of persons who
practise that process, or manufacture and prepare the various
material and articles required in it. The discovery of chlorine by
Scheele led to the invention of the modern processes of bleaching,
and to various improvements in the dyeing of the textile fabrics, and
has given employment to a very large number of our Lancashire
operatives. The discovery of chlorine has also contributed to the
employment of thousands of printers, by enabling Esparto grass to be
bleached and formed into paper for the use of our daily press. The
numerous experimental investigations in relation to coal-gas have
been the means of extending the use of that substance, and of
increasing the employment of workmen and others connected with its
manufacture. The discovery of the alkaline metals by Davy, of