mineral oils to lighthouses, but there are
certain risks connected with the use of
petroleum and paraffine which make it
particularly undesirable that they should be
employed on such an important duty.

It is probable that many people wonder
why gas is not more generally used; but
there are numerous objections in the way
at present. The light, it is found, would
certainly be a little better than the oil
flame; but to change from oil to gas would
involve a large outlay for new burners,
&c., and an entire sacrifice of the present
valuable oil lamps in the numerous
lighthouses; then, again, it would be necessary
to establish for each lighthouse gasworks
with numerous outbuildings and cumbrous
machinery, to do which, at most stations,
would be dreadfully expensive, and at all
rock stations impossible; and the
difficulties in the way of conveying sufficient
quantities of coal to the outlying and
distant lighthouses would be most serious.
To balance these drawbacks, the gain would
be only a little brighter light, and so the oil
light has retained its supremacy.

The oxy-hydrogen or lime light has been
experimented upon; but the complicated
arrangements for producing the light, and
the uncertainty of its steady maintenance,
have proved serious objections to its
application to the lighting our coasts.

Magnesium also has been tried. No doubt
those who have watched the ascent of the
magnesium balloons on firework nights at
the Crystal Palace, have thought that really
such a beautiful, brilliant light might be in
some manner made useful; and truly, if a
light of such a power could be placed in a
lighthouse, its splendour would almost light
up the dark waves, edging them all with
silver, and its piercing rays would project
their light even beyond the horizon. But
its unreliability and its insufficient development
make it inapplicable at present.

Many other kinds of light have been
tried, but only one has at present shown
itself so superior to other lights, and so
manageable, as to justify the authorities
in placing it at a lighthouse. We
refer to the electric light, produced by
magnetic induction, which may fairly be
said to be the "coming" light.

The low outstretching point of Dungeness
is now marked by the electric light,
and like a beautiful star it meets the sailor's
eye as he comes above the horizon on a
dark night. In comparison with its
intense white light the flame of the burning
oil appears of a yellow or sometimes a
reddish colour, and altogether of a softer
nature; while the vivid brightness of the
electric spark seems to pierce the darkness
with extraordinary power. It is surprising
to think that there really is no body of flame
to produce this brilliant effect, but indeed
it is nothing more than white heat caused
by the meeting of two opposing electric
currents. These currents are generated by
a powerful electrical machine, the motive
power to which is supplied by steam; and
are conveyed up to the lamp by two copper
wires, each terminating in a carbon point.
These two points have to be kept at a certain
distance from each other, and when the
two opposite currents meet at these points,
the resistance of one against the other
causes the tips of the carbons to glow,
become white hot, and to melt or fuse, and
the incandescent or molten state of the
carbon points is the brilliant electric light
itself. At the Exposition in Paris in 1867
the splendid effect of this light might have
been seen. A building was erected in the
park for the purpose of showing it off, and
eye-witnesses speak of it as something
marvellous, how a clearly defined horizontal
beam was projected through the darkness,
lighting up objects for many miles. The
French authorities have not been slow to
discover the value of the light, for already
they have adopted it at the lighthouse at
Cape La Hève, and indeed they seem to
fancy that to them belongs the principal
credit for bringing the light into use. But
it is well known that the grand discovery
of Professor Faraday of the principle of
generating electricity by magnetic induction
was first utilised by Professor Holmes,
who invented an apparatus for producing
light thereby, which was tried in 1859 at
the South Foreland Lighthouse. Our
neighbours, however, with their quick
perception, soon elaborated the somewhat
imperfect apparatus of Professor Holmes;
but that gentleman has since completely
outstripped the Frenchman by a new and
improved machine.

So much for some of the sources of light:
we have yet a few words to say regarding
the means adopted to make the most of
them.

There was a time when no one thought
of trying to make something more of a
light than there really was; nothing was
known of such things as reflectors or other
aids to light, so that coal fires blazed, and
candles cast their flickering feeble rays on
the waters, quite unassisted. However, it
was discovered at last that light could be