Improvements in Light Reflectors.
Year: 1893

page_text: Date of Application, 21st Mar., 1893
Complete Specification Left, 21st Dec., 1893-Accepted, 27th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in Light Reflectors.
1, FEDELE CARELLO trading as Carello Brothers, of Via San Massimo No. 31
Turin in the Kingdom of Italy, Manufacturer and Dealer, do hereby declare the
nature of this invention to be as follows:-
The improved reflector consists of a series of metallic rings inflected according
to parabolic curves determined and arranged around the orifice of a reflecting
apparatus, partly hemispheric, partly parabolic; in the centre of which is the light
whose rays consequent on their reflection by the said rings, are all sent in the
direction of the axis of the apparatus, united in a cluster of a diameter equal to
that of the largest or exterior ring.
The general form of the apparatus is that of a globe, as represented in the
drawing resembling those of ground glass with which ordinary household lamp3 for
burning petroleum oil &c. are provided.
The parabolic curves of the reflecting rings are drawn according to the following
geometrical rule.
We will examine the ray AP which from the luminous body A is directed
towards P into space.
If from its point it is desired to reflect it on SOR
parallel to the axis A X of the apparatus, it suffices to arrange at O a reflecting
surface MN inclined with regard to AO at such an angle that the reflected
ray OR makes with M N an angle of reflection equal to the angle of
incidence AO M.
Evidently the line M N of this surface or rather its direction at O will be that
of the bisectrice of the angle AOS equal by apposition to the angle POR, and
by the same reason A O M being equal to N O P the ray OR will have a direction
parallel to the axis A X.
In practice the bisectrice of A OS can be immediately determined by fixing on
the prolongation of the axis AX a distance A a equal to AO; the right line a O
is the bisectrice required.
For the ray AC coming from A with the process indicated there will be at V Z
the line of another surface reflecting the ray AC in the direction C R¹.
By joining the point C with the point O the right line CO will make the
angle CO M with the line M O.
If with the method indicated the corresponding line is fixed at the point D, placed
at the intersection of the two bisectrices of COM and CAO, there will be a third
line of a surface of reflection which like the two first M N, V Z will be a tangent to
the parabolic are CDO, the geometric point of which will be completely determined
by successive intermediary points between the extremes already fixed. Supposing
that this parabolic arc CDO turns around the axis A X, maintaining all its points
at a constant distance from the axis (makes a revolution around A X) it will
generate an annular parabolic surface reflecting all the rays emanating from A
and comprised in the sector CAO.
The same reasoning applies to all the other arcs C¹O', C" O" &c. corresponding
to the sectors OA O, O'A O" &c.
From that it may be concluded that all the rays emanating from the centre A
and belonging to the front hemisphere (or toward X) will be reflected by the said
rings quite parallelly in the direction A X. The number of reflecting rings can
be reduced by a third or even by a half, or can also be increased if they be
constructed with the greatest precision in all their parts.
With regard to the rays projected into the posterior hemisphere, it is evident

page_text: that on account of the reflection by the spherical parts T T U U having their
common centre at A, the rays which fall on these parts are thrown back each in a
contrary sense in its own radial direction so that on repassing again by A are
reflected by the corresponding rings of the anterior hemisphere which send them
with the preceding rays in the direction A X.
The single part TU surrounding the axis AX' also takes the parabolic form
with regard to the centre A; and that for the double purpose of preventing
firstly the double reflection of the rays comprised in the sector TA U which alone
can be thus projected directly in the direction A. X--and secondly to avoid the
necessity for increasing too much the number of the parabolic rings in proximity
to the axis AX where they would become too long and too near together-and in
short to prevent the loss (though very small) of these few rays projected conically
instead of in parallel directions.
In practice however it will be advisable to forego this advantage, at the most
very small, in view of the greater facility for constructing the posterior hemisphere
of the apparatus of a section entirely semi-circular and with a single radius instead
of several which would be necessary by the parabolic form of the arc T U.
A metallic band shown at T'O, Un connects to the posterior hemisphere the
exterior parabolic ring CO thus closing solidly the apparatus. On the exterior
edge of this conical band are soldered the ends of a cross piece Omn which
connects and fixes all the interior rings.
By the description of the geometrical arrangement above indicated are given all
the elements necessary to the exact and practical construction of this new ray
diffuser, which may be made of any suitable material (silver, brass or copper
silvered or nickeled &c.) and which is susceptible of very wide industrial
applications for the usual reflector of a candle or study lamp, for lanterns and
signal lights fixed or movable on railways, ships &c.-for instruments used in
physics, for laryngoscopical apparatus and others but more especially for all cases
where it is necessary to have a projection, collected in a single direction, of a
quantity of very intense light as in lighthouses, for mountain climbing and for the
army and navy.
Any source of light may be utilized in the apparatus here described; such as
candles, lamps for burning oil, petroleum, benzine, gas, magnesium, electric light &c.
But in cases where it is necessary to obtain good effects, it is always preferable to
use magnesium, oxyhydrogen light and above all the electric light; because being
possible to fix the luminous centre always exactly in the centre of the apparatus
and without either glasses or chimneys for the smoke and with the least possible
number of supports (always cumbersome and putting parts of the apparatus in
shade) all the light produced is far more easily and more completely utilized.
D
000
CARELLO FEDELE,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Light Reflectors.
I, FEDELE CARELLO, trading as Carello Brothers, of Via San Massimo No. 31,
Turin, in the Kingdom of Italy, Manufacturer and Dealer, do hereby declare the
nature of this invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
The improved reflector consists of a series of metallic rings inflected according
to parabolic curves determined and arranged around the orifice of a reflecting
apparatus partly hemispheric, partly parabolic, in the centre of which is the
luminous focus, whose rays, consequent on their reflection by the said rings, are all

page_text: sent in the direction of the axis of the apparatus united in a cluster of a diameter
equal to that of the largest or exterior ring.
The general form of the apparatus is that of a glóbe, as represented in the
drawing accompanying my Provisional Specification, similar to those of ground
glass with which ordinary household lamps for burning petroleum oil, &c., are.
provided.
The parabolic curves of the reflecting rings are drawn according to the following
geometrical rule.
We will examine the ray A P, which, from the luminous focus A, is directed
towards P into space. If, from its point O, it is desired to reflect it on SOR,.
parallel to the axis A X of the apparatus, it suffices to arrange at O, a reflecting
surface M N inclined with regard to AO at such an angle that the reflected ray OR
makes with M N an angle of reflection equal to the angle of incidence AO M.
Evidently the line M N of this surface, or rather its direction at O, will be that of
the bisectrice of the angle A OS, equal by apposition to the angle P O R, and by the-
same reason, A O M being equal to N.O P, the ray OR will have a direction
parallel to the axis A X. In practice the bisectrice of A OS can be immediately
determined by fixing on the prolongation of the axis A X, a distance A a equal:
to A O; the right line a O is the bisectrice required.
For the ray A C coming from A, with the process indicated, there will be-
at V Z the line of another surface reflecting the ray A C in the direction C R'..
By joining the point C with the point O, the right line C O will make the.
angle COM with the line M O.
If, with the method indicated, the corresponding line is fixed at the point D,.
placed at the intersection of the two bisectrices of CO M and CA O, there will
be a third line of a surface of reflection, which, like the two first M N, V Z, will
be a tangent to the parabolic arc CD O, the geometric point of which will be
completely determined by successive intermediary points between the extremes.
already fixed. Supposing that this parabolic are CDO turns around the
axis AX, maintaining all its points at a constant distance from the axis, (makes a
revolution around A X), it will generate an annular parabolic surface reflecting
all the rays emanating from A and comprised in the sector CAO.
The same reasoning applies to all the other arcs C' O', C³ O³, &c., corresponding.
to the sectors A O¹, O'A O³, &c.
From that it may be concluded that all the rays emanating from the centre A
and belonging to the front hemisphere (or towards X) will be reflected by the said
rings quite parallelly in the direction A X. The number of reflecting rings can
be reduced by a third or even by a half, or can also be increased if they be
constructed with the greatest precision in all their parts.
With regard to the rays projected into the posterior hemisphere, it is evident
that, on account of the reflection by the spherical parts T T¹, U U', having their
common centre at A, the rays which fall on these parts are thrown back, each in a
contrary direction to its own radial direction, so that on repassing again by A, they
are reflected by the corresponding rings of the anterior hemisphere, which send
them with the preceding rays in the direction A X.
The part T U surrounding the axis A X' should also take the parabolic form
with regard to the centre A, and that for the double purpose of preventing, firstly,.
the double reflection of the rays comprised in the sector T A U, which alone can
be thus projected directly in the direction A X, and, secondly, to avoid the
necessity for increasing too much the number of the parabolic rings in proximity to
the axis AX, where they would become too long and too near together, and in
short to prevent the loss (though very small) of these few rays projected conically
instead of in parallel directions. In practice however it will be advisable to forego.
this advantage, at the most very small, in view of the greater facility for
constructing the posterior hemisphere of the apparatus of a section entirely semi-
circular and with a single radius instead of several, which would be necessitated by
the parabolic form of the arc T U.

page_text: A metallic band shown at T¹ O, U₁n, connects to the posterior hemisphere the.
exterior parabolic ring CO, thus closing solidly the apparatus. On the exterior
edge of this conical band are soldered the ends of a cross piece O m n, which
connects and fixes all the interior rings.
By the description of the geometrical arrangement above indicated, are given all
the elements necessary to the exact and practical construction of this new ray
projecting reflector, which may be made of any suitable material, (silver, brass, or
copper silvered or nickelled &c.), and which is susceptible of very wide industrial
applications for the usual reflector of a candle or study lamp, for lanterns and
signal lights, fixed or movable, on railways, ships, &c., for instruments used in
physics, for laryngoscopical apparatus and others, but more especially for all
cases where it is necessary to have a projection, collected in a single direction, of a
pencil of very intense light, as in lighthouses, for mountain climbing, and for the
army and navy.
Any source of light may be utilized in the apparatus here described, such as
candles, lamps for burning oil, petroleum, benzine, gas, magnesium, electric light,
&c., but in cases where it is necessary to obtain good effects, it is always preferable
to use magnesium, oxyhydrogen light, and above all the electric light, because,
being possible to fix their luminous centre always exactly in the centre of the
apparatus, and without either glasses or chimneys for the smoke, and with the
least possible number of supports (always cumbersome and putting parts of
the apparatus in shade), all the light produced is far more easily and more
completely utilized.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
In an apparatus to reflect the rays from a luminous source all united in one
direction, the combination of a rear hemispherical reflector, the central part of
which is either parabolic or not, with an anterior series of annular parabolic
reflectors arranged concentrically one within the other and around the axis of the
cluster of light rays to be projected, substantially as herein shown and described
and for the purposes indicated.
Dated this 21st day of December 1893.
FEDELE CARELLO,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.