Improvements in the Transformation of Heat into Electricity and in Apparatus for that Purpose.
Year: 1886

page_text: Date of Application, 21st May, 1886.
Complete Left, 19th Feb., 1887.
Complete Accepted, 22nd Mar., 1887.
Improvements in the Transformation of Heat into Electricity and in
Apparatus for that Purpose.
I, CHARLES CLAMOND, of No. 23 Boulevard de Strasbourg, Paris in the Republic
of France, Engineer do hereby declare the nature of this invention to be as follows:-
This invention relates to the transformation into electricity of a portion of the heat
evolved from any source, and more particularly from the combustion of fuel in a fire
place. Although the apparatus to which this invention relates may be considered as
relating to thermo-electricity, yet it is based upon new laws and facts discovered by me,
and which I will first explain in order that the fundamental principles of my invention
may be readily understood.
Assuming a series of bodies endowed with energetic thermo-electrical powers to be
placed in a row, every alternate body of the row being positive, such as is an alloy of
antimony and zinc, while the other bodies are negative, such as galena or sulphide of
lead, and assuming that between each positive and negative body is placed a block
of metal having sufficient conducting powers of heat and electricity, such as copper,
silver nickel, iron &c., which blocks I term "inter-contacts," and assuming further
that while one set of alternate blocks is heated, the other set is cooled, the development
of the electro motive forces will be subject to the following law which I have discovered:
they are namely, a function of the difference of temperature between the two series of
inter contacts, and are independent of the temperature of the thermo electric bodies or
of any parts of these.
The following may serve as an example of the experiments from which I have
deduced this law.
Two parallel bars, one consisting of an alloy of antimony and zinc, and the other of
galena have at one end each an inter-contact which are separated from each other by a
non-conductor, while at the other end they have a single intercontact cominon to both.
On heating the last named intercontact and cooling those first named and connecting
these by wires to a galvanometer, the ordinary current of a thermo-electric couple will
be observed to flow from the antimony-zinc bar through the one intercontact and wire
connection to the other intercontact and galena bar and thence through the intercontact
at the other end back to the antimony zinc bar.
If now the heated intercontact be placed against the cooled ends of the bars, and the

page_text: cooled intercontacts against the heated ends, the same electromotive force and the same
current will be obtained as before but circulating in the contrary direction, yet always
going from the hot intercontact to the cold intercontact in the antimony zine bar, and
from the cold intercontact to the hot inter contact in the galena bar. If again the
whole or parts of the bars be heated to any desired degree, and these be touched at any
point by the intercontacts the same result will always be obtained, which proves that
the difference of temperature between the intercontacts alone determines the electro-
motive force and the direction of current produced.
I have determined the theory of these phenomena, which consists in that the seat of
the transformation of the heat into electricity does not lie in the mass of the thermo-
electric bodies, nor even in the material element constituting the surfaces of the
contacts, but in the very small spaces actually existing between them at their points of
contact, and which therefore constitute the theoretical intercontacts, so that the
transformation takes place and the current is produced simultaneously and instantane-
ously, before even the thermic circulation has had time to establish itself between the
contacts and intercontacts and the thermo-electric bodies.
It is to be understood that it is advantageous that the metal of the intercontacts
should be a good conductor of heat, so that it may readily convey the caloric to the
theoretical intercontact.
This law has for its first practical result, to dispense with the necessity of maintain-
ing the two ends of a thermo-electric body at different temperatures, as has been done.
up to the present time, and consequently to allow of the substitution for the long bars,
simple thin plates, which are lighter, less expensive, and much less resisting to the
passage of electric currents, it being sufficient to maintain the intercontacts at different
temperatures at the same time, as the said plates do not require to participate in the
temperatures of the intercontacts, they are not subject to the deterioration that results
when they are exposed to high temperatures. This discovery of the seat of the
transformation of heat into electricity also permits of the determination of the
conditions of maximum of useful effect of this transformation, which are as follows:
Taking two series of homogenous actively thermo-electric bodies, the maximum yield
of transformation of heat into electricity will be the better attained, if the relative
resistances to heat of the elements of the complete circuit, are so arranged that a
greater portion of the decrease of thermic potential (fall of temperature) is effected
between the surfaces of contact of the intercontacts and those of the active bodies.
In other words, if the resistances of the thermic circuit are for the the useful
resistance and for the connections or passive resistances, the useful effect will
The following is the principle of the construction which I am thus led to adopt:
Assuming that a flat plate of thermo electric material of considerable area as
compared with its thickness has its surfaces divided into a number of small squares,
and that against each such square a pointed metallic conductor be made to bear, there
being a pair opposite each other on each side of the plate, and assuming that the
conductors on the one side be heated while those on the other side are cooled, then the
two portions of the thermic resistance at the points of contact will be very considerable
as compared with the thermic resistance offered by the active body thus a small
quantity of heat will pass at each pair of conductors, making collectively a large
quantity, and this transmitted heat will be utilised to the greatest advantage.
Practically, the points of the conductors, which should not be too fine, should pass
to a certain extent into the active body, the important point being that the section of
contact of the conductor with the plate be restricted as much as possible.
The points of the conductors may be made with circular or longitudinal grooves for
increasing the surface of contact. The acuteness of the points of the conductors is
favorable for the electric circulation, as it tends to diminish the electrical resistance on

page_text: he passing of the current from the contact rod to the generally less perfect conducting
material of the thermo-electric substance, through the infinitesimal arc that separates
them. The contacts may however be spherical, plane cylindrical &c., so long as they
are of restricted extent.
Thus in constructing a thermo-electric element according to this method, various
arrangements may be adopted, in all of which however the inter-contact bodies, are
formed with a number of pointed projections that are in contact with the positive and
negative thermo electric bodies, the heated inter-contacts being in contact with one
side, and the cooled ones with the other side of the said bodies.
For preventing transmission of heat by radiation, which would represent a loss, the
spaces between the inter contacts and bodies are filled in with a bad conductor of heat.
For preventing as much as possible the fracture of the thermo-electric plates owing to
unequal expansion and contraction, it is preferred to make grooves in them between
the contiguous points of the inter contacts. With this arrangement any fracture will
take place at the grooved part, and will consequently not affect the action of the
apparatus.
In place of using continuous plates for the thermoelectric bodies, these may consist
of a series of cubes or cylinders each of which has a pair of inter-contacts.
The inter contact rods which are generally made of copper or other metal may be
coated with a double layer of electroplating the first coating which is of nickel,
protects the rods against the corrosive action of the active bodies, and the second
coating which is of silver, improves the contacts and prevents oxidation at elevated
temperatures.
Instead of pointed rods toothed plates may be used for the inter contacts.
Compound elements may be formed by combining together a number of the thermo-
electric bodies in two groups, one consisting of positive and the other of negative
bodies, the plates or bodies of each group being connected together by inter contact
rods, the inter contacts at the one end of the two groups being formed into one.
With such an arrangement the advantage is gained of having a greatly increased
resistance to the passage of heat, without a corresponding increase of resistance to the
electric current, the former increasing about as the square of the number of plates
while the latter only increases directly as the number.
This arrangement also permits of the use, in forming the element, of several different
active bodies having thermoelectric action of the same sign, those plates which are
most heated being formed of substances of higher melting point than the others.
Thus for the former may be used an alloy of antimony and zine, while for the latter
may be used an alloy of antimony and cadmium, which is more energetic but also more
easily fusible. Although in forming these elements I prefer to use energetic bodies,
such as the alloy antimony and zinc (about 2 of antimony to 1 of zinc) for the
positive element, and galena for the negative one, yet bodies may also be employed
that are less far removed from one another in the thermoelectric scale, and even simple
metals may be used.
In this case the forms of the bodies may be somewhat modified to facilitate
manufacture, and also on account of their greater conductivity. Thus square or other
shaped plates may be fixed together by rods of copper or other good conductin
metal.
When the one element of the battery is composed of an energetic body and th
other element of a less energetic body, the latter may be constructed as last describe
while the former is constructed as previously described.
The thermoelectric bodies may also assume the shape of cylinders, while the inter-
contacts are made of rectangular blocks in contact with the cylindrical surfaces of
the former.
Instead of employing galena by itself as the negative thermoelectric body, a
compound may be used consisting of about 100 parts galena, 10 to 15 parts sulphide
of copper, and 6 to 10 parts metallic antimony. The addition of sulphide of copper
increases the fusibility and homogenity of the galena, and increases its thermoelectric
powers, while the antimony increases its conductibility without weakening to any

page_text: material extent its electromotive force. For forming the contacts I utilise the property
of antimony of uniting with galena without having chemical action therewith at a high
temperature, by interposing a layer or coating of antimony between the inter-contacts
and the thermoelectric body. For facility of manufacture of the elements, I arrange
the inter contacts with their points projecting into moulds having the form of the
thermoelectric bodies, and I then run the fused material for forming these into the
moulds, which may either be removed after solidification of the bodies, or they may
remain, forming part of the element.
A complete thermoelectric apparatus constructed and operating as above described
may consist, by way of example, of a series of couples of the above described elements
arranged in a circle or otherwise round a source of heat, such as a gas jet, the inter
contacts on the inner ends of the, elements being formed of tubular structures having
narrow longitudinal slots presented towards the flame, so that the hot gases can enter
them within these are other tubes closed at their upper ends and having openings on
the side diametrically opposite the said slots, so that, the hot gases, after passing
round in the outer tube, enter the inner tubes, which are connected at bottom to an
annular hollow base communicating with a chimney, and which is enclosed by a jacket,
through which the air supply to the burner passes so as to become heated.
The spaces between the elements are filled with a bad conductor of heat and
electricity such as spun glass, abestos &c.
The apparatus may be provided with a regulator of any known construction acting
by expansion on heating, which is connected to the cock on the gas pipe, so as to close
this more or less when the heat exceeds a certain degree.
In some cases the inner tubes of the inner inter contacts may be dispensed with and
outer tubes be provided with small tubular nozzles projecting inwards, in place of
slots, while the gases escape through a small opening at the bottom of the tubular
inter-contact.
ABEL & IMRAY,
28, Southampton Buildings, London, W.C., 30
Agents for the Applicant.

page_text: I, CHARLES CLAMOND, of No. 23 Boulevard de Strasbourg, Paris in the Republic
of France, 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 :-
This invention relates to the transformation into electricity of a portion of the heat
evolved from any source, and more particularly from the combustion of fuel in a fire
place.
Although the apparatus to which this invention relates may be considered as relating
to thermo electricity, yet it is based upon new laws and facts discovered by me, and
which I will first explain in order that the fundamental principles of my invention
may be readily understood.
Assuming a series of bodies A G, Fig. 1 of the accompanying drawings, endowed
with energetic thermo-electrical powers, to he placed in a row, every alternate body A
of the row being positive, such as is an alloy of antimony and zinc, while the other
bodies G are negative, such as galena or sulphide of lead, and assuming that between
each positive and negative body is placed a block of metal CC, F F, having sufficient
conducting powers of heat and electricity, such as copper, silver, nickel, iron &c.,
which blocks I term "inter contacts;" and assuming further that while one set of
alternate blocks CC is heated, the other set F F is cooled, the development of the
electromotive forces will be subject to the following law which I have discovered; they
are namely a function of the difference of temperature between the two series of inter
contacts, and are independent of the temperature of the thermo electric bodies or of
any parts of these.
The following may serve as an example of the experiments from which I have
deduced this law.
Two parallel bars, one consisting of an alloy of antimony and zine A Z Fig. 2 and
the other of galena G A have at one end N each an inter contact F which are
separated from each other by a non conductor I, while at the other end M they have
a single inter contact. C common to both. On heating the last named inter contact C
and cooling those first named F, and connecting these by wires to a galvanometer y
the ordinary current of a thermo electric couple will be observed to flow from the
antimony zinc bar A Z through the one inter contact F and wire connection to the
other inter contact F and galena bar GA and thence through the inter contact C of
the other end back to the antimony zine bar.
If now, as in Fig. 3, the heated inter contact C be placed against the cooled ends N
of the bars, and the cooled intercontacts F against the heated ends M the same electro
motive force and the same current will be obtained as before, but circulating in the

page_text: contrary direction from the cold to the hot in A Z, and from the hot to the cold in
GA, yet always going from the hot inter contact to the cold intercontact in the
antimony zine bar A Z, and from the cold intercontact to the hot intercontact in the
galena bar GA. If again the whole or parts of the bars be heated to any desired
degree, and these be touched at any point by the intercontacts C and F, the same
result will always be obtained, which proves that the difference of temperature
between the intercontacts C and F alone determines the electromotive force and the
direction of current produced.
I have determined the theory of these phenomena, which consists in that the seat of
the transformation of the heat into electricity does not lie in the mass of the thermo
electric bodies, nor even in the material element constituting the surfaces of the
contacts, but in the very small spaces actually existing between them at their points of
contact, and which therefore constitute the theoretical inter contacts, so that the
transformation takes place and the current is produced simultaneously and instan-
taneously, before even the thermic circulation has had time to establish itself between
the contacts and intercontacts and the thermo-electric bodies.
It is to be understood that it is advantageous that the metal of the intercontacts
should be a good conductor of heat, so that it may readily convey the caloric to the
theoretical intercontact.
This law has for its first practical result, to dispense with the necessity of maintain-
ing the two ends of a thermo-electric body at different temperatures, as has been done
up to the present time, and consequently to allow of the substitution for the long bars,
simple thin plates, which are lighter, less expensive and much less resisting to the
passage of electric currents, it being sufficient to maintain the inter contacts at
different temperatures. At the same time as the said plates do not require to
participate in the temperatures of the intercontacts, they are not subject to the
deterioration that results when they are exposed to high temperatures. This discovery of
the seat of the transformation of heat into electricity also permits of the deter-
mination of the conditions of maximum of useful effect of this transformation, which
are as follow:
Taking two series of homogeneous actively thermo-electric bodies, the maximum
yield of transformation of heat into electricity will be the better attained, if the
relative resistances to heat of the elements of the complete circuit, are so arranged
that a greater portion of the decrease of thermic potential (fall of temperature) is
effected between the surfaces of contact of the intercontacts and those of the active
bodies.
In other words, if the resistances of the thermic circuit are for the useful
resistance and for the connections or passive resistances, the useful effect will
increase in proportion to
1 + 2
1
or 1 +
The following is the principle of the construction which I am thus led to adopt:
Assuming that a flat plate of thermo electric material A. B Fig. 4 of considerable
area as compared with its thickness, has its surfaces divided into a number of small
squares m, and that against the centre of each such square a pointed metallic
conductor CF be made to bear, there being a pair opposite each other on each side of
the plate as shewn, and assuming thht the conductors on the one side be heated while
those on the other side are cooled, then the two portions of the thermic resistance at
the points of contact will be very considerable as compared with the opposite thermic
resistance offered by the active body; thus only a small quantity of heat will pass at
each pair of conductors, but making by the collective action of a large number of such
pairs a large quantity, and this transmitted heat will be utilised to the greatest
advantage

page_text: to a certain extent into the active body, the important point being that the section of
contact of the conductor with the plate be restricted as much as possible.
Fig. 4 bis shews the arrangement employed for this purpose of the conductors, the
points being made to approach within a short distance of each other in the plate.
The points of the conductors may be made with circular or longitudinal grooves as at
for increasing the surface of contact. The acuteness of the points of the conductors
is favorable for the electric circulation, as it tends to diminish the electrical resistance
on the passing of the current from the contact rod to the generally less perfect
conducting material of the thermo electric substance, through the infinitesimal are that
separates them. The contacts may, however, be spherical, plane, cylindrical &c., so
long as they are of restricted extent.
Thus in constructing a thermo electric element according to this method, various
arrangements may be adopted, in all of which, however, the intercontact bodies are
formed with a number of pointed projections that are in contact with the positive and
negative thermo electric bodies, the heated intercontacts being in contact with one
side, and the cooled ones with the other side of the said bodies.
Figs. 5 and 6 shew a complete thermo-electric element constructed according to the
above described principles. The two arrangements only differ in the relative positions
occupied by the several parts. In both cases A. and G are the thermo electric plates,
the one being positive and the other negative, C and F are metal plates or blades to
which are soldered stems (, the ends of which enter into the plates A and G. The
plates C and F together with the stems constitute the intercontacts, the plate C
receiving heat from any suitable source, while I' is cold, the difference between their
temperatures determining the electro-motive force of the couple.
As it is essential that the heat should pass entirely through the stems t¹, and heat
transmitted by radiation from C to A and G and from the plates A and G to F being
lost for the transformation, the spaces between these parts round the stems are filled
with a bad conductor of heat, such as asbestos paper, glass powder &c., which prevent
such transmission by radiation.
For preventing as much as possible the fracture of the thermo-electric plates A. and G
owing to unequal expansion and contraction, it is preferred to make grooves rrin
them between the contiguous points of the intercontacts, thus dividing the plates into
squares as shewn at Fig. 6. With this arrangement any fracture will take place at
the grooved part, and will consequently not affect the action of the apparatus.
In place of using continuous plates for the thermo-electric bodies, these may consist
of a series of cubes or cylinders each of which has a pair of inter contacts; or when
only a weak current is required a single such cube or cylinder may be employed.
The intercontact rods tt, which are generally made of copper or other metal, may
be coated with a double layer of electro plating; the first coating, which is of nickel,
protects the rods against the corrosive action of the active bodies, and the second
coating which is of silver, improves the contacts and prevents oxidation at elevated
temperatures.
Instead of pointed rods may be used toothed plates for the inter-contacts, as at
Fig. 7, the teeth taking the place of the points of the rods. Or in place of serrations,
the blades may have a continuous sharp contact edge.
Compound elements may be formed for increasing the effect produced by the simple
elements above described, by combining together a number of the thermo electric
bodies A A A³.....GG G³, Fig. 8 in two groups, one consisting of positive and
the other of negative bodies, the plates or bodies of each group being connected
together by inter-contact rods, the inter contacts C at the one end of the two
groups being formed into one. With such an arrangement the advantage is gained of
having a greatly increased resistance to the passage of heat, without a corresponding
increase of resistance to the electric current, the former increasing about as the
square of the number of plates A² A².. G G2, while the latter only increases directly
as the number. Thus if y is the quantity of heat that, in a unit of time and for a
given difference of temperature between G and F. passes through the simple element

page_text: Fig. 6, when the circuit thereof is open and no current is produced, the quantity of
heat, which, under the same conditions, will pass through the multiple element of a
number of plates, will be The electrical constants of the simple element being
E and R, those of the multiple element will be about E and n R. Now the
maximum quantities of heat that each of these couples can give off in an external
conducting circuit being given by the formulae simple element
JE
:
JE²
4R multiple
element 4nR (J being the coefficient of Joule) the total quantities of heat consumed
by the couples will be: For the simple elementy +
JE2
4 R
for the multiple element
+
JE²
4nR
; the ratios between the quantities of heat taken up and consumed will
be For the simple element: 7' =
7° n
JE²
JE²
4Rq + JE² for the multiple element
= 4Rq + JE²; it will be seen therefore that the useful effect increases with n,
22
that is to say, with the number of plates of the multiple element, and that it tends
towards unity when the number of plates is indefinitely increased. This arrangement
also permits of the use, in forming the element, of several different active bodies
having thermo-electric action of the same sign, those plates which are most heated
being formed of substances of higher melting point that the others. Thus in the
arrangement at Fig. 8 for the plate A¹ may be used an alloy of antimony and zinc,
while for the plates A² and A³ may be used an alloy of 806 parts by weight of
antimony and 606 parts by weight of cadmium, which is more energetic but also more
casily fusible.
Although in forming these elements I prefer to use energetic bodies, such as the
alloy antimony and zinc (about of antimony to 1 of zinc) for the positive
element, and galena or sulphide of lead for the negative one, yet bodies may also be
employed that are less far removed from one another on the thermo-electric scale, and
even simple metals such as antimony, iron, nickel &c. may be used. In this case the
forms of the bodies may be somewhat modified to facilitate manufacture, and also on
account of their greater conductivity.
Thus square or other shaped plates may be fixed together by rods of copper or other
good conducting metal as shewn at Fig. 9, which shews a couple of nickel and
antimony. The pieces a¹ a² a³ of nickel and the plates 1 12 of antimony being
consequently connected together by means of rods t t of copper; the heat passes from
C to passing successively from one plate to the next in following the same laws
above set forth, whereby the useful effect is increased.
When the one element of the battery is composed of an energetic body, such
as antimony and zinc alloy, and the other element of a less energetic body, such as
nickel, the latter may be constructed as at fig. 9, while the former is constructed as at
Fig. 8. Fig. 10 shews this arrangement.
"
The thermo-electric bodies may also assume the shape of cylinders as shewn at
Fig. 10 bis, a¹ a² being of nickel, antimony &c and 2 of copper or other
good conducting metal, generally of a smaller diameter. The separate parts are secured
together by soldering at the points of contact.
Instead of employing galena by itself as the negative thermo-electric body, a com-
pound may be used consisting of about 100 parts galena, sulphide of copper 10 to 15
parts, and metallic antimony 6 to 10 parts melted together. The addition of sulphide
of copper increases the fusibility and homogeneity of the galena, and also increases
its thermo-electric powers, while the antimony increases its conductability without
weakening to any material extent its electro motive force. This compound

page_text: at
12
may also be obtained by calcining the mixture at the temperature
which the antimony fuses, whereby, on cooling, the whole becomes a solid
mass, which may have the forms shewn at Figs. 5, 6 and 8. For forming the
contacts I utilise the property of antimony of uniting with galena without having
chemical action therewith at a high temperature, by interposing a layer or coating
Fig. 12 of antimony between the inter-contacts and the thermo-electric body united
either by fusion or by electro deposit. For facility of manufacture of the elements, I
arrange the inter-contacts with their points projecting into moulds D1 D2 D3 Fig. 11
having the form of the thermo-electric bodies, and I then run the fused material for
forming these into the moulds, which may either be removed after solidification of the
bodies if made of separable parts of metal &c., or they may remain forming part
of the element being in that case formed of materials that are bad conductors
of electricity and heat.
The grouping together of a certain number of the elements above described
and shewn in Figs. 5, 6, 8, 9, 10 constitute an apparatus for transforming heat into
electricity. The source of heat may be of any suitable kind, and the forms and
dimensions of the elements may be greatly varied, according to the circumstances
under which they are employed and the results to be obtained."
I will describe, by way of example, the construction of an apparatus operating by
means of the heat developed by the combustion of gas, petroleum &c., such as is shewn
in sectional elevation and sectional plan at Figs. 13 and 14.
This apparatus consists of a number of superposed rings of couples such as herein-
before described. In place of being in rings they might be arranged rectilineally or
otherwise. The couples here shewn are of the same type as those described with
reference to Fig. 10, that is to say multiple elements formed of plates A' A2 A3 of an
alloy of antimony and zinc and of composite plates L formed of nickel. The elements
of one and the same ring are shewn coupled together in tension; but this coupling
may be effected otherwise, for instance, in vertical rows. Each two consecutive rings
are separated by a disc of insulating material d such as a sheet of asbestos. All the
lateral spaces between two contiguous couples, as also the spaces between the
plates A A² are filled with substances R R that are bad conductors both of heat and
of electricity, such as glass powder, asbestos paper and other insulating powders, in
order that the heat may only be conveyed by the conduction of the couples as described.
This quantity of heat is so small, owing to the arrangements adopted, that the outer
surface of the inter-contact plate F suffices to diffuse it in the surrounding atmosphere.
The apparatus is heated by means of any suitable burner, the couples being so arranged
as to take up heat from the combustion gases.
At Fig. 13 is shown an ordinary bunsen burner. The Hot intercontacts of the
elements CC are cach composed of a metallic blade to the metal of which are
soldered the rods tt and the composite nickel plate Land of which the two ends are
bent round as shown in plan, Fig. 14, in order to surround a vertical tube T which is
thus made to traverse all the intercontacts of one vertical row of couples. These
tubes T are closed at top and open at bottom where they communicate with the
annular chamber M which, in its turn, communicates with the chimney flue N
for the escape of the combustion gases. These gases enter in the direction of
the arrows into the internal space of each inter-contact C to which they impart their
heat and afterwards they pass by a hole p into the tubes T which convey them into the
chamber M. In passing through this chamber the remaining heat of the gases
partially utilised by causing the entering air passing in through openings S of the
casing B to pass over the outer surface of the said chamber M and thus take up heat
therefrom on its way to the burner. In each of the chambers formed by each inter-
contact C the tubes T are provided with an opening p which has the effect of restricting
the flow of the gas and causing them to be uniformly distributed throughout the
couples. The space between the curved ends of the inter contacts C is made very
narrow in order to offer the requisite resistance to the flow of the gas, which
resistance increases with the temperature of the intercontact. By this means the less
is
B

page_text: heated intercontacts receive the greater amount of heat and thus a very uniform
distribution of the caloric over the several elements is automatically effected.
The apparatus may be provided with a small safety apparatus such as is
shewn at r, Fig. 14, which, when the temperature of the plate C exceeds a
certain degree, closes the orifice p and thus prevents the entrance of the liot gases to
the burner. This small apparatus may consist of a plate constructed of two or more
metals having different degrees of expansion, which plate, when heated, is
consequently bent in one direction in the well known manner and is thus made to
close the opening p at a certain degree of heat.
The part of the inter contact C which collects the heat may be variously formed,
but its essential feature is to present, firstly, an orifice which serves to restrict the flow
of the combustion gases and, secondly, a narrow passage through which the gases
flow and of which the resistance to the flow increases with the temperature. Fig. 15
shews another form of this arrangement. The tubes T are dispensed with and the
bent plates C, forming cylinders themselves, constitute the passages for the escape of
thic gases.
A tube of small diameter m, through which the combustion gases enter,
serves to fulfil both the above named conditions.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is
1. The construction of apparatus for transforming heat into electricity wherein
metal pieces serving both to conduct heat and electricity and herein termed
inter-contacts, are interposed between thermo electric elements, the alternate
intercontacts being maintained at different temperatures, whereby electro-motive
force is generated independently of the temperatures of the different parts of the
thermo electric bodies, substantially as herein described.
2. Apparatus for transforming heat into electricity wherein the transmission of heat
is controlled solely by the thermic resistance of the surfaces of thermo electric bodies
and of conducting bodies in contact, whereby active bodies of small thickness and
limited mass are capable of being employed, as the thermic resistance of these bodies
themselves is not required to effect the control of the transmission of heat, substantially
as herein described.
3. The herein described arrangements of apparatus wherein the most favorable
conditions for the transmission of heat into electricity are obtained by restricting the
contact between the ends of intercontact rods and the thermo-electric bodies, such
contact being distributed over a number of different points on the opposite surfaces of
the said bodies.
4. In the arrangement of thermo electric apparatus referred to in the preceding
claim, the grooving of the surfaces of the thermo electric bodies between the points of
contact with the intercontacts so that on fracture occurring this will not affect the
action of the contacts, substantially as herein described.
5. The construction of multiple thermo electric elements, consisting of two or more
blocks or plates of the same thermo electric substance, or of different substances
having the same electric action, connected together by metallic rods or pieces,
substantially as herein described, whereby the useful effect of the clement is increased.
6. The herein described manufacture of negative elements of sulphide of lead, in
combination with metallic antimony for forming the contacts.
7. The construction of thermo electric apparatus herein described, so arranged as to
take up heat from the combustion gases of a fire place and to transmit the same
uniformly to the several elements composing the apparatus.
Dated this 19th day of February 1887.
ABEL & IMRAY,
Agents for the Applicant.