IMPROVED APPARATUS FOR COLLECTING RAYS OF LIGHT AND HEAT.
Year: 1875

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
-ply
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVED APPARATUS FOR COLLECTING RAYS OF LIGHT AND HEAT.".
A communication from abroad by Pasquale Balestrieri, of Naples,
in the Kingdom of Italy.
Scaled the 1st June 1875, and dated the 9th January 1875.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 9th January 1875.
I, ALEXANDER MELVILLE CLARK, of 58, Chancery Lanc, in the County
5 of Middlesex, Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVED APPARATUS FOR COLLECTING RAYS OF LIGHT AND
HEAT," to be as follows:-
This Invention relates to apparatus, to which I give the name of
armillary photo-thermo collector, for collecting the rays of light and heat
radiating from a luminous centre.

page_text: The collector of this Invention may be constructed according to two
arrangements, the one based on a plane, the other on a spherical surface;
and each arrangement may be composed of two parts, anterior and
posterior. The anterior portion is that placed between the centro of
radiation and the point on which the collection of rays are projected, i
while the hinder portion is placed on the other side of the luminous
centre, and reflects the rays back towards the said centre. For example
let O, B, Figure 1, of the accompanying Drawing be a horizontal line
at one end of which is drawn a line A, A', perpendicular therto. The
line O, B, will be the axis of the apparatus of the plane arrangement. 1
The point O in this line is the optical centre, and the point F at which
is placed the luminous or calorific centre (according as it is desired to
project rays of light or of artificial heat to a distance) is termed the
focus. Consequently if the rays from the focus be projected towards B¹
any apparatus placed between F and B' would be termed the anterior 1
apparatus, and another placed between F and B the posterior apparatus.
I will first describe the construction of the anterior apparatus of the
plane arrangement. Let A, A', be a line drawn perpendicular to the
axis divided into equal parts, 1, 2, 3, 4, 5, 6, 7, and upwards on either
side of point O, similar divisions 1, 2, 3, 4, and upwards being made a
along the axial line O, B, commencing at point O. I then take one of
these latter divisions, 4' for example, as the focus, and from this point 4¹
(which is coincident with point F) to points 1, 2, 3, &c., I draw the
right lines F, F, F³, &c., which I term radii. These lines F', F³, &c.,
I then apply to line O, B, making one end coincide with point F, and
mark off their length by points 1, II., III., &c., and draw other right
lines to points 1, 2, 3, &c., respectively, these latter being called
generating lines.
The portions of the generating lines la, 2b, 3c, 4d, 5e, 6ƒ, 7g, &c.,
comprised between any two successive radii I term segments. This being
understood let it be supposed that the perpendicular O, A, turns on the
optical centro O, it will, while still remaining perpendicular to axis B', B,
describe a plane perpendicular to the axis, and the linear segments la,
26, &c., will describe right segments of cones, all of which have a
common axis O, F. Thus the bases of these cones are all in the same a
plane perpendicular to the axis, and the divided lines 07 in Figure 1
represent the profile of this plane, the lines la, 2b, 3c, &c., similarly
representing the profiles of the segments of cones. Hence I have termed

page_text: the above the plane arrangement. It is these segments of cones which
constitute the "armillary collector," as will be now explained. If
these segments be of metal and made specular, that is to say, polished
for the purpose of reflecting the light from their inner surfaces, the com-
3 bination of segments will constitute what I term the anterior apparatus
of the armillary collector on the plane principle, and each segment of a
cone will be an annulus. To complete the apparatus there must be added
what may be termed its complement. This is a luminous body if light
- is to be collected, or a heated body if heat is to be concentrated. This
> luminous or heated body is placed in the focus F in such manner that
the centre of its anterior surface shall correspond exactly to the point 4'
if it is desired that the pencil of rays shall be parallel. This I term the
radiating centre. By slightly advancing or withdrawing this centre the
rays may be made to converge or diverge as may be desired. The
5 dimensions of the apparatus is determined by the area of the radiating
body, and should be such that the posterior diameter a, a, of the central
segment is equal to the diameter of the radiating body.
In practice in order to combine these rings or annuli to form an
apparatus ribs or intermediate supports would be employed to hold them
together, beginning at the central or first ring, which is connected by
ribs to the next or second one, the second to the third, and so on to the
outermost ring or periphery. Four such ribs are disposed at equal
distances around the periphery of the central ring, on which is super-
posed the polished surface of the second polished ring. The latter is
similarly provided with four ribs on its periphery, on which the third
ring is fitted, and so on, care being taken that the front edges of the
rings shall all be in the same plane, for which purpose the ribs of each
part are made to correspond in form to the trapeziums la, 62, c3, &c.
The number of the ribs should be increased as the diameters of the cones
become greater in order to afford sufficient support to the rings which
fit the one in the other, and the whole in the outermost one which is fixed
in a solid rim, as shown in section at A, A³, Figure 1, which is itself
enclosed by a copper or other sheet metal cylinder or casing, shown
at An, An. Any number of rings may be combined in the above
manner. The apparatus is enclosed at front and back of the cylinder by
glasses at A, A, m, m³, so as to protect the same from external influences,
and the cylinder is supported by gudgeons R, R', hung in bearings in
a forked stand, so as to be capable of being inclined at any angle to the

page_text: horizon. The forked stand may be also made to swivel on a vertical axis
in order to admit of the apparatus being turned towards any point of the
horizon. The construction of the apparatus is shown in Figure 3. The
metal of which the rings are composed should be selected according to
the use to which the collector is to be applied. The best kinds would
be made of copper with its surface silvered and burnished, but they may
also be constructed of tin plate or German silver, each of which will
retain their polish when protected from air charged with moisture or
oxydizing vapors.
When any given number of degrees of light are to be collected these
degrees are measured as follows:-A line is drawn through the focus F
perpendicular to the axis O, B, and a circle C, C', C", is described from F
as a centre with a radius Fa. One half of the given number of degrees
is then marked off on either side of line O, B, i.c., from C¹ to C, and
C to C". From the centre F through the two points C and C" right
lines are drawn to the plane A, A', which thus determines the extent of
this plane. It will thus be evident that the anterior apparatus A, A',
collects 60°x2 or 120 degrees of light.
In the above manner apparatus may be constructed of very largo
diameter, which will collect the greater portion of the rays from a
luminous centre, or which will collect a very large quantity of solar
rays.
The posterior portion of the plane arrangement consists simply of a
concave mirror made of the same metal as the rings before mentioned.
It is however not required, except it be desired, to collect the rays of the
posterior hemisphere, and this is in the majority of cases unnecessary, as
the anterior apparatus alone will answer all requirements. This posterior
apparatus serves to double the amount of light, which when collected is
measured on the same circle, as shown in Figure 1, where it will be seen
that the mirror M, M', M", collects 120 degrees of light. The mirror
may be arranged in two different ways, according to the effect
desired.
I may here mention that the effect produced by the anterior apparatus
alone is that of a series of concentric rings of light corresponding in
number to the sections, alternating with as many dark rings. This
arrangement would be particularly useful in many cases, such as in
lighthouses for example, as it would enable mariners to distinguish the

page_text: light from any other. I therefore deem it essential to retain this same
arrangement, even when the posterior apparatus is added, in which case
the mirror is so disposed that the focus F shall be coincident with its
centre of curvature, as is the case with m, m³, m", Figure 1. In this case
the mirror will collect all the degrees of the arc a, a'. Thus the anterior
and posterior apparatus m, m², m", together collect 240 degrees of light.
When applied for other purposes it may be requisite to have a uniform
plane of light, in which case the mirror would be arranged at a distance
from focus of one half its radius of curvature. This is the case with
the mirror M, M³, M", which collects only one half of the degrees of the
arca, a¹, viz., 45 degrees. The two apparatus combined will thus collect
165 degree.
The plane arrangement before described could not collect 180 degrees
of light, except theoretically, that is to say, by supposing the plane of
the rings to be extended to infinity, which is impossible in practice, as
it is only possible to extend the plane,or to increase the number of annuli
to an indefinite extent. This arrangement is of especial advantage when
it is desired to project to a distance a very considerable luminous surface.
A large collector of above 6 feet in diameter has been constructed
according to this plane arrangement. This plane arrangement is also to
be preferred for collecting the solar rays in the focus. The grouping
being as the square of the diameters a collector of 6 fect diameter would
condense the solar light 31,400 times, supposing the area of the focus to
-be 1.550 of a square inch. It is however of advantage to sometimes
collect the wholo 180 degrees of the anterior hemisphero in as limited a
space as possible, for which purpose I prefer to use the spherical
arrangement illustrated in Figure 2. I take a point C as a centre, from
which I describe a circle 0 × 1 having a radius O, C, which is
determined in advance. The diameter O, B, of this circle is the axis.
The radius O, C, is then divided into two equal parts at point F, which
is the focus. The distance O, F, is then divided into as many equal
parts as desired, for example, with five parts indicated by the points 1',
. 2¹, 3', 4', 5', similar divisions being laid off on the arc P, O, P', on either
. side of point O, as indicated by the numbers 1, 2, 3, 4, 5, &c. At point F
is erected on either side of the axis O, B, the perpendicular P, P¹, said
perpendicular being the chord of the arc P, O, P¹, which determines the
sphericity of the collector, which will contain as many rings as there
are graduations, less one. From point F are drawn right lines or radii
to points 1, 2, 3, 4, &c., which lines are then marked off from point F

page_text: (their common centre) at points I., II., III., &c., from which are drawn
right lines 1 I., 2 II., &c., to serve as the generating lines of the cones,
the parts la, 2b, &c., representing the segments of which the rings are
composed, for the rest the same method is adopted as in the plano
arrangement.
E
The area of the radiating centre, which is placed at point F being
known the posterior diameter a, a, of the central ring is determined
thereby. It will be seen that this arrangement, which measures nearly
one-fourth of the circle, will collect the wholo or nearly the whole 180
degrees of light or heat, and it is only the area of the luminous source 1
which determines the effect obtained. This said diameter determines
more or less exactly the radius of the circle O × B which defines all
the rest, as above mentioned.
A posterior apparatus or mirror may also be combined with this
spherical arrangement, the optical centre of which mirror should bo 1
placed at point C, which is the centre of circle O × B; but in the
majority of cases the anterior apparatus only is used, it being sufficiently
powerful for most purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent 20
Office on the 8th July 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent. Majesty Queen Victoria, by Her 2
Letters Patent, bearing date the Ninth day of January, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
licence, that I, the said Alexander Melville Clark, my executors, 3(
administrators, and assigns, or such others as I, the said Alexander
Melville Clark, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times

page_text: and the point O in this line the optical centre, and the point F, at which
is placed the luminous or calorific body (according as it is desired to
project rays of light or of artificial heat to a distance) is termed the focus.
Now if the rays from the focus be projected towards B¹ the part of the
apparatus placed between F and B' would be termed the anterior, and
that between F and B the posterior part of the apparatus.
.
I will first describe the construction of the anterior portion when based
upon a plane. Let the right line A, A', of infinite length and perpen-
dicular to the axis, be divided into any number of equal parts, 1, 2, 3, 4,
5, 6, 7, &c. on either side of point O, and let corresponding divisions 1',
2, 3, 4', &c., be made along the axial line O, B, commencing at point O.
I then take one of these latter divisions, 4' for example, as the focus,
and from this point 4' (which is coincident with point F) to points 1,
2, 3, &c. on line A, A', I draw the right lines F¹, F³, F³, &c., which I
term radii. These lines F, F³, &c., I then apply to line O, B, making
one end coincide with point F, and mark off their other ends by pivots
I., II., III., &c., and from these points I., II., III., &c., I draw other
right lines to points 1, 2, 3, &c., respectively, these latter being called
generating lines.
The portions of the generating lines la, 2b, 3c, 4d, 5e, 6f, 7g, &c.,
comprised between any two successive radii, I term segments. This being
understood, let it be supposed that the perpendicular O, A, turns on tho
optical centre O, it will, while still remaining perpendicular to axis B', B,
describe a plane perpendicular to the axis, and the linear segments la,
26, &c., will describe right segments of cones, all of which have a
common axis O, F. Thus the bases of these cones are all in the same
plane, perpendicular to the axis, the said planes being indicated by tho
fine lines 07, whilst the thick lines la, 2b, 3c, &c., represent tho
segments of cones, and these lines are thickened to represent the cross
section of the metal of which the concentric segments of cones which
constitute the "armillary" collector are constructed. These segments
are constructed of sheet metal and made specular, that is to say, polished
on their inner surfaces for the purpose of reflecting the light. This
combination of concentric segments constitutes what I term the anterior
part of the apparatus of the armillary collector, and each segment of a
cone will be an annulus. To complete the apparatus there must be
added what may be termed its complement. This is a luminous body if
light is to be collected, or a heated body if heat is to be concentrated.

page_text: This luminous or heated body is placed in the focus F in such manner
that the centre of its anterior surface shall correspond exactly to the
point 4' if it is desired that the pencil of rays shall be parallel. This
I term the radiating centre. By slightly advancing or withdrawing this
centre the rays may be made to converge or diverge, as may be desired.
The dimensions of the apparatus is determined by the area of the
radiating body, and should be such that the diameter at a, a, of the
central segment is equal to the diameter of the radiating body.
The conical segments or rings are connected or held together by radial
ribs or intermediate supports, as shown in face view, Figuro 3. Four
such ribs are disposed at equal distances around the periphery of the
innermost cone or ring, on which is fitted the polished surface of the
second ring. The latter is similarly provided with four ribs on its
periphery, on which the third ring is fitted, and so on, care being taken
that the front edges of the rings shall all be in the same plane, for which
purpose the ribs of each part are made to correspond in form to the
trapeziums 1a, 62, 2b, c3, &c. The number of the ribs should be increased
as the diameters of the cones become greater in order to afford sufficient
support to the cones or rings, which fit the one in the other, and the
whole in the outermost one, which is fixed in a solid rim, as shown in
section at A, A', Figure 1, which is itself inclosed by a copper or other
sheet metal cylinder or casing, shown at An, A', n². Any number of
these rings or cones may be combined in the above manner. The
apparatus is enclosed at front and back of the cylinder by glasses at A, A²,
n, n', so as to protect the same from extornal influences, and the cylinder
is supported by gudgeons R, R', hung in bearings in a forked stand, so
as to be capable of being inclined at any angle to the horizon. The
forked stand may be also made to swivel on a vertical axis in order to
admit of the apparatus being turned towards any point of the horizon.
The construction of the apparatus is shown in Figure 3. The metal of
which the rings are composed should be selected according to tho use to
which the collector is to be applied. The best kinds would be made of
copper,
with its concavo surface silvered and burnished; but they may
also be constructed of tin plate or German silver, each of which will
3 retain its polish when protected from air charged with moisture or
oxydizing vapors.
When any given number of degrees of light are to bo collected these

page_text: dingly. A line is drawn through the focus F perpendicular to the
axis O, B, and a circle C, C¹, C", is described from F as a centre with a
radius F, a. One half of the given number of degrees is then marked off
on either side of line O, B, i. e., from C' to C, and C to C". From the centre F
through the two points C and C" right lines are drawn to the plane A, A',
which thus determines the extent of this plane. It will thus be evident
that the anterior apparatus A, A³, collects 60° × 2 or 120 degrees of light,
and that apparatus may be constructed of very large diameter, which
will collect the greater portion of the rays from a luminous centre, on
which will collect a very large quantity of solar rays.
The other portion of the apparatus in rear of the radiating centre
consists simply of a concave spherical mirror, and may be made of the
same metal as the rings. It is however not required, except it be desired
to collect the backwardly projected rays, and this is in the majority of
cases unnecessary, as the anterior apparatus alone will generally be
sufficient. This posterior reflector serves to double the amount of
light, as will be seen by measurement on the same circle C, C². The
mirror may be arranged in two different ways, according to the effect
desired.
I may here mention that the effect produced by the anterior apparatus
alono is that a series of concentric zones of light corresponding in
number to the conical segments or rings, and alternating with as many
dark zones. This arrangement would be particularly useful in many
cases, such as in lighthouses for example, as it would enable mariners to
distinguish the light from any other. In order to retain this effect when
the posterior apparatus is added it is necessary that the mirror should be
so disposed that the focus F shall be coincident with its centre of
curvature, as is the case with mirror m, m², m", Figure 1. In this caso
the mirror will collect all the rays comprised in the arc a, a', and thus
the anterior portion of the apparatus, together with the mirror m, m², m", ɛ
will collect 240 degrees of light. When applied for other purposes it
may be requisite to have a uniform plane of light, in which case the
mirror would be placed at a distance of one half its radius from focus F.
M, M³, M", represents a mirror so arranged, which collects only one
half of the degrees of the arc a, a¹, viz., 45 degrees. In this case the 8
two apparatus combined will collect 165 degrees.
It has been calculated above that the plane arrangement will theoreti-
cally collect 180 degrees of light by supposing the plane of the rings to

page_text: be extended to infinity, but it is not possible to attain this result in
practice. This arrangement is of especial advantage when it is desired to
project to a distance a very considerable luminous surface, and a large
collector of two metres (about 6 ft. 6 inches) in diameter has been used
for this purpose. This arrangement is also to be preferred for collecting
the solar rays in the focus. A collector of two metres diameter would
condense the solar light 31-400 times, supposing the area of the foous
to be one square centimetre (155·086 of a square inch). It is however
sometimes of advantage to collect the whole 180 degrees of the anterior
hemisphere in as limited a space as possible, for which purpose I prefer
to uso the spherical arrangement illustrated in Figure 2. In con-
structing this arrangement I describe from a point O as a centre, and
with a radius 0, 0, determined beforehand, a circle O × B. The
diameter O, B, of this circle is the axis of the apparatus. The
radius O, O, is then divided into two equal parts at point F, which is
the focus, and the distance O, F, is then divided into as many equal
parts as desired. Let thero be for example five of these parts, as
indicated by the points 1, 2, 3, 4, 5'. Corresponding divisions aro
then laid off on the arc P, O, P³, on cither side of point O, as indicated
by the numbers 1, 2, 3, 4, 5, &c.; at point F is crected on either side of
the axis O, B, the perpendicular P, P', said perpendicular being the
chord of the arc P, O, P¹, which determines the sphericity of the collector,
which will contain as many rings as there are graduations, less one.
From point F are drawn right lines or radii to points 1, 2, 3, 4, &c., and
the lengths of these lines are then marked off from point F along line
O, B, at points I., II., III., &c., from which latter points are drawn
right lines 11., 2II., &c. to serve as the generating lines of the cones of
the parts 1a, 2b, &c., representing the segments of which the rings are
composed; for the rest the same method is adopted as in the plane
arrangement.
The area of the radiating centre, which is placed at point F, being
known, the posterior diameter a, a, of the central ring is determined
thereby. It will be seen that this arrangement, which measures nearly
one-fourth of the circle, will collect the whole or nearly the whole 180
degrees of light or heat, and it is only the area of the luminous source
which determines the effect obtained. The diameter of this area
determines more or less nearly the radius of the circle O × B, by which
all the rest is defined, as above mentioned.

page_text: A posterior mirror may also be combined with this spherical arrange-
ment, the optical centre of which mirror should coincide with point C,
which is the centre of the circle Ox B; but in the majority of cases
the anterior apparatus only is used, it being sufficiently powerful for
G
most purposes.
Having described the nature of the Invention, and the manner of
performing the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is, the
apparatus designated the armillary photo-thermo collector, consisting of
conical concentric rings a, b, c, d, &c., arranged and constructed upon ]
the principles herein described and illustrated in the Drawings, sub-
stantially as and for the purposes specified.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Eighth day of July, in
the year of our Lord One thousand eight hundred and seventy- 1
five.