IMPROVEMENTS IN THE FRAMING OF LIGHTHOUSE LANTERNS AND OF THE OPTICAL APPARATUS OF LIGHTHOUSES
Year: 1867

page_text: LETTERS PATENT to David Marr Henderson, of Smethwick, in the County
of Stafford, Civil Engineer, for the Invention of "IMPROVEMENTS IN THE
FRAMING OF LIGHTHOUSE LANTERNS AND OF THE OPTICAL APPARATUS OF
LIGHTHOUSES."
Sealed the 7th January 1868, and dated the 12th July 1867.
PROVISIONAL SPECIFICATION left by the said David Marr Henderson at
the Office of the Commissioners of Patents, with his Petition, on the
12th July 1867.
I, DAVID MARR HENDERSON, of Smethwick, in the County of Stafford, Civil
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE FRAMING OF LIGHTHOUSE LANTERNS AND OF THE OPTICAL APPARATUS
OF LIGHTHOUSES," to be as follows:-
In constructing or framing lighthouse lanterns according to my Invention
I employ frames fitted together in tiers, each frame being complete in itself,
and having its sides of any required section; these frames may be cast in
gun metal, cast iron, or other suitable metal or alloy, but I prefer to make
them by forging and welding out of wrought iron or steel rolled to the required
section. The frames may also be formed out of bar iron or steel by placing a
narrow frame inside a wider one, and rivetting or otherwise securing the two
together, care being taken to properly for the rabate for the glass. The

page_text: lautern may be either polygonal or cylindrical, the former shape being adapted
for the reception of panes of flat glass, and the latter for panes of cylindrical
glass; but I prefer the cylindrical form as being better suited for fitting the
tiers together so as vertically to break joint when desired, and also allowing
the rays of light from the apparatus to pass normally through the glazing.
In forming a lantern the frames are fitted together edge to edge, and
secured to each other by rivets, screws or otherwise, the tops and bottoms
forming a level surface corresponding with the divisions of the optical apparatus
and the top and bottom sills or other framing or connecting pieces, the object
of breaking joint in the framing or excentering the various tiers is to prevent
an obstruction of the light from the apparatus by the bars of the framing
from extending throughout its entire height on any arc of the sea.
The light
on the sea is thereby rendered more uniform.
In the case in which inclined lens panels are used in the optical apparatus
I prefer to make the tiers of the lantern frames corresponding with them of
triangles, each alternate triangle being inverted; lozenge-shape frames may be
used in place of triangular ones, but they are inferior in strength to triangular
frames. The number of frames used is immaterial, but to reduce the
obstruction of light to a minimum their number and position should be
arranged to suit the optical apparatus which they surround. Where the whole
horizon is not illuminated the frames may be strengthened by diagonals in the
dark are, or replaced by solid frames or plates.
The breaking joint vertically or excentering of the frames herein-before
described with reference to the framing of lighthouse lanterns is also applicable
to the framing of the optical apparatus of lighthouses.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said David Marr Henderson in the Great Seal Patent Office on
the 8th January 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
MARR HENDERSON, of Smethwick, in the County of Stafford, Civil Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of July, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirty-first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
David Marr Henderson, Her special licence that I, the said David Marr

page_text: Henderson, my executors, administrators, and assigns, or such others as I, the
said David Marr Henderson, my executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN THE FRAMING OF LIGHTHOUSE LANTERNS AND OF THE OPTICAL APPARATUS
OF LIGHTHOUSES," upon the condition (amongst others) that I, the said David
Marr Henderson, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said David Marr Henderson, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:-
In constructing or framing lighthouse lanterns according to my Invention
I employ frames fitted together in tiers, each frame being complete in itself
and having its sides of any required section; these frames may be cast in gun
metal, cast iron, or other suitable metal or alloy; but I prefer to make them
by forging and welding out of wrought iron or steel rolled to the required
section. The frames may also be formed out of bar iron or steel by placing a
narrow frame inside a wider one, and rivetting or otherwise securing the two
together, care being taken to properly form the rabate for the glass. The
lantern may be either polygonal or cylindrical, the former shape being adapted
for the reception of panes of flat glass, and the latter for panes of cylindrical
glass, but I prefer the cylindrical form as being better suited for fitting the
tiers together so as vertically to break joint when desired, and also allowing
the rays of light from the apparatus to pass normally through the glazing.
In forming a lantern the frames are fitted together edge to edge, and secured
to each other by rivets, screws, or otherwise, the tops and bottoms forming a
level surface corresponding with the divisions of the optical apparatus and the
top and bottom sills or other framing or connecting pieces. The object of
breaking joint in the framing or excentering the various tiers is to prevent an
obstruction of the light from the apparatus by the bars of the framing from
extending throughout its entire height on any arc of the sea. The light on
the sea is thereby rendered more uniform.

page_text: In the case in which inclined lens panels are used in the optical apparatus
I prefer to make the tiers of the lantern frames corresponding with them of
triangular frames, each alternate frame being inverted; by this means the bars
of the lantern can be made to coincide optically with the framing of the optical
apparatus, and at the same time greater strength is given to the framing of
the lantern. Lozenge-shaped frames may be used in place of the triangular
ones, but they are inferior in strength to the triangular frames, and require
staying in lanterns where several frames are used side by side. The number
of frames used is immaterial, but to reduce the obstruction of light to a
minimum their number and position should be arranged to suit the optical
apparatus which they surround. Where the whole horizon is not illuminated
the frames may be strengthened by diagonals in the dark arc, or replaced by
solid frames or plates; this is more particularly advisable where rectangular
frames are employed throughout, and a large amount of excentering is
adopted.
The breaking joint vertically or excentering of the frames herein-before
described with reference to the framing of lighthouse lanterns is also applicable
to the framing of the optical apparatus of lighthouses.
Having explained the nature of my Invention I will proceed to describe,
with reference to the accompanying Drawing, the manner in which the same
is to be performed.
Figure 1 represents a sectional elevation taken through the vertical axis of
an arrangement of rectangular panels fitted together in three tiers of sixteen
frames each and excentered.
Figure 2 is a part sectional plan taken through the centre of the upper tier
of Figure 1.
Figure 3 represents a sectional elevation taken through the vertical axis of
an arrangement of rectangular frames in the upper and lower tiers, and
triangular frames in the centre tier, which latter are adapted for inclined lens
frames, and increase the rigidity and strength of the framing. The said
Figure 3 is a convenient arrangement for lights illuminating the whole
horizon, as in their case the introduction of staying would be accompanied by
a loss of light.
Figure 4 is a part sectional plan taken through the centre of the upper tier
of Figure 3.
Figure 5 is an enlarged section of the framing showing how the sides of
the frames may be secured together, and how the capping may be fastened to
the framing so as to hold the plate glass in its place.
Figure 6 is an enlarged section of the framing showing how it can be made

page_text: out of ordinary bar iron or steel without having iron or steel rolled to the
required section, but this section is not preferred, as it is weaker for the same
weight of iron and involves more workmanship.
a, a, are the rectangular frames; b, b, are the triangular frames; c, c, is a
section of rolled iron, or steel, or cast metal, which may be modified to suit the
thickness of the plate glass or the fancy of the designer, and may be ornamented
with a moulding d, d, capping preferred of gun metal to secure plate glass,
and secured to frames by screws e, e, preferred of gun metal; f,f, plate glass;
9, 9, rivets holding frames together; h, h, small rivets used in making a frame
of separate pieces of flat bar iron or steel.
Having now described the nature of my Invention, and the manner in which
the same is to be performed, I wish it to be understood that I do not limit
myself to the precise details herein described and illustrated, as the same
may be varied without departing from the nature of my Invention; but I
claim as my Invention the several improvements in the framing of lighthouse
lanterns, and of the optical apparatus of lighthouses, substantially as herein-
before described and illustrated in the accompanying Drawing.
In witness whereof, I, the said David Marr Henderson, have hereunto
set my hand and seal, this Second day of January, in the year of
our Lord One thousand eight hundred and sixty-eight.
Witness,
FELIX MASSELI,
19, Rue Taranne,
Paris.
DAVID MARR HENDERSON. (L.S.)