increased by having a reflecting surface
behind it, and at one of the coal fires a mild
attempt at reflection was made by placing
a flat roughly polished brazen plate on the
land side of the fire. But as time went on,
and other improvements in lights were
made, it came about that reflectors began
to be extensively used, and the system of
lighting called catoptric was gradually
developed. Science lent her aid to the
maturing of this important branch of
national duty, and ultimately a lighting
apparatus was produced, consisting of a
number of argand lamps on a framework,
each with a reflector behind. We might
greatly puzzle our readers, were we to enter
into the consideration of the details respecting
the proper shape, &c., of these
reflectors. We might discourse a great deal
about the rays of incidence and reflected
rays, about parabolic, concave, and
spherical reflectors, and we might indulge in a
heap of technical talk which would plunge
most readers into a state of hopeless
bewilderment, but such details would not be
generally interesting. The arrangement
with lamps and reflectors was certainly
very good; indeed, the practical proof of
that is, that it has been used for over fifty
years; but some clever personage at last
thought of the plan of magnifying one
large flame with a lens, and this was the
beginning of a system of lighting called
dioptric.

Instead of the number of lamps was
substituted one powerful oil light, a light
produced by four (or fewer) circular wicks,
one inside the other, with a little space
between each. It seems rather a strange
statement to make, that the object is to burn
these wicks as little as possible; but such
is really the case. By an ingenious
mechanical contrivance, a regular supply of
oil is arranged—in fact, a constant overflow
is maintained, so that the wicks are
literally deluged with oil, and thus, to a
great extent, prevented from charring, while
the oil alone burns. The flame is generally
kept up to a height of three and a half
inches, which itself is no mean light,
being constituted of four distinct flames
from the four wicks. But a splendid
arrangement is now adopted for making
much more of this light, and for so
directing its rays that only a little light
is lost. It will be readily understood that,
from such a body of flame as has been
described, the light would radiate in all directions,
and therefore for lighthouse purposes
a good deal of it would be wasted, because
the rays are wanted to be thrown only on
the sea to be of service to mariners, and
not to be lost up in the air, nor underneath
on the floor of the lantern, or the ground on
which the lighthouse stands. So it was
thought that possibly some of this wasted
light might be reclaimed and made serviceable,
and, after a number of trials, a plan
was established, which is now in general
and successful operation at most of our
British lighthouses. Inside the great glass
lantern, which is usually about twelve feet
high, is placed another framework of glass,
corresponding in some extent to the shape
of the lantern, and enclosing the lamp.
This framework is composed, firstly, of a
band of glass round the middle, called the
lenticular belt, placed on a level with the
flame, whereby the light is considerably
magnified. At the top, the framework
forms a circular dome, and is composed of
a number of peculiarly shaped pieces of
glass, called prisms, so adjusted that every
ray of light emanating from the oil flame
is intercepted by one of these prisms, and
is thereby diverted from the course it would
have taken, had it not been interfered with.
As it is, the ray is refracted or bent, and
instead of going up into the sky is sent out
on to the sea. The lower part of the
apparatus is another set of prisms, which, in
a similar manner, prevent the light being
wasted below. Thus is the light sent out
from a lighthouse lantern to strike the sea
as far as the line of the horizon in a
compact body, and as clearly defined as the
sun's rays striking into a darkened room.
The light from the Eddystone streams out
all round, something like a huge umbrella,
the tower forming the stick; and it would
be quite possible to get right in underneath
the light, only it would be dangerous to
venture into the unillumined part on
account of the treacherous reefs that surround
the Eddystone. If sailors know themselves
to be in the neighbourhood, and cannot see
the light, they know at once they are in
danger.

Many will think that, if the oil light can
be made so much of by the dioptric
apparatus, how much more can be done with
the electric light? And no doubt, as the
development of the powers of this
wonderful luminary progresses, the further
application of the dioptric system will render
it even more splendid. At present this
system is applied in a very limited way.
There are six orders of dioptric lights, and
the electric light has only the lowest or
sixth-order apparatus. There is a proposal
now under consideration for lighting buoys
and beacons by electricity, to send out two