IMPROVEMENTS IN THERMO-ELECTRIC APPARATUS."
Year: 1875

page_text: LETTERS PATENT to Charlton James Wollaston, of 8, Park Place,
Marylebone, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN THERMO-ELECTRIC APPARATUS."

page_text: I employ elements of conical or pyramidal form, and at the base of
the cone or pyramid is the heated junction, the conical or pyramidal
element being seated in a cast-iron or other metal cup, beneath which is
a gas burner. I either apply a separate gas burner to each heated
junction, or all the heated junctions may be inserted into one common 5
enclosed and heated chamber in which a high and uniform temperature
is maintained by gas or other fire. The elements may be set in a fire-
tile suitably perforated or indented with holes to receive them.
I sometimes build up the elements so that between a heated and a
cooled junction there are several intermediate junction surfaces.
10
In order to carry away heat from the cooled junctions I provide water
cups upon them, and I cause water to fall drop by drop into and from
the cup so that no electrical connection may be established by the water;
or to cool the junctions of the elements I so shape them that they may
dip into water; or I insert in the joint a strip of a metal which conducts 1
heat well, and cause it to dip into a cup of water. To insulate the
elements in the parts required I coat them with a vitreous glaze.
Sometimes I screw or rivet the elements together, or when the
elements consist of thin strips or bands in order to get a good electric
connection at the junctions I roll or fold the two straps or bands 20
together; I insert a rivet through the roll or fold so formed. In this
way I connect a large number of elements into a chain which I coil
round so as to enclose a heating space of approximately a conical form,
wide at the base and tapering to a narrow aperture for the escape of the
products of combustion at the top.
I sometimes arrange the elements in an arch over the heating portion
of the apparatus in order to permit a more ready radiation from the cool
ends.
2
In order to maintain a uniform current. I arrange electro-magnetic
apparatus in circuit, which closes and opens the aperture by which the 3
gas is supplied as the current increases or falls off. Or if solid fuel be

page_text: filed by the said Charlton James Wollaston in the Great Seal
Patent Office on the 6th July 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLTON
JAMES WOLLASTON, of 8, Park Place, Marylebone, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria by Her
Letters Patent, bearing date the Sixth 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 Charlton James Wollaston, Her
special licenso that I, the said Charlton James Wollaston, my execu-
tors, administrators, and assigns, or such others as I, the said Charlton
James Wollaston, my executors, administrators, and assigns, should at
3 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 Inven-
tion for "IMPROVEMENTS IN THERMO-ELECTRIC APPARATUS," upon the condition
(amongst others) that I, the said Charlton James Wollaston, my execu-
tors 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 Lotters Patent.
NOW KNOW YE, that I, the said Oharlton James Wollaston, 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 :—
This Invention has for its object improvements in thermo-electric
apparatus.
In order to obtain electricity by the expenditure of heat I as hereto-
fore couple thermo-electric elements and heat the junctions, whilst
other portions of the elements are cooled, or allowed to cool. The

page_text: half circle of elements may at its ends be coupled with binding screws
c, c, which allow of the method of coupling being easily varied as
circumstances may render desirable, or they may be permanently coupled
in one continuous series or in several series for intensity or for quantity.
'
In place of arranging the elements on a semicircular fire-tile, as
described, I employ a cylindrical tile, which then serves as a chimney
for the gas burner; it is similarly slotted to receive the thermo-electric
couples. Or in place of forming slots completely through the tile the
tile may be only indented so that the ends of the couples are protected
from the direct or intenser action of the flame. Or sometimes where the
elements employed will withstand the heat required for the process I
coat the junctions to which heat is to be applied with enamel by the
well-known process by which the saucepans and other iron articles are
commonly enamelled. I can then dispense with the fire-tile and allow
the coated ends of the couples to come into close contact the one with
the other; or the ends of the elements may bo- bedded in a fireproof and
non-conducting composition, such as fire-clay mixed with powdered talc.
The elements may conveniently form a continuous chain, coiled round
so as to enclose a conical space or chimney.
•
From a long series of experiments I have found the most advantageous
arrangement of thermo-electric couples to consist of strips of German
silver and tinned iron, cut in the form shown at Figure 3, about + an inch
at the broad end, inch at the narrow end, and 5 or 6 inches long.
They are folded together at the broad end so as to secure a large surface
in contact, and rivetted or screwed through and soldered with tin solder.
A diagram of the joint is shown at Figure 4. Any number of these
couples or elements may be joined up in series, the narrow end of the
positivo motal of one couple being soldered to the narrow end of the
negative metal of the next couple, and so on to any number.
:
The form of the strips I believe to be important as it allows of a ready
means of securing a large surface of the two metals being in contact at
the heated junction.
I have found that the narrow ends may be reduced to as small a size
as is consistent with strength with advantage to the electric effect.
Where tinned iron is employed as one of the elements the heat should
not be sufficiently high-to-melt-the-tin-although no intee will: moonlk.
:

page_text: to the apparatus from this temperature being occasionally exceeded.
Or, as already mentioned, I cool the outer junctions of the couples by
fixing small metal water cups at the junction, and I arrange for water
to drip into and from these cups. Where the couples are placed one
above the other the water can be made very conveniently to drop from {
eup to cup, the supply being sufficient to prevent the water becoming
materially heated before it reaches the lower cups. Or the joints may
dip into water cups; in this case the cups must be insulated.
When, as for electro plating, the approximate uniformity of the
quantity of the current is important I employ an automatic regulator, 1
which renders the supply of gas or of air, as the case may be, dependant
on the amount of the electric current. I cause the current to deflect a
galvanometer needle, and in connection with the needle I apply clock-
work apparatus, which at short intervals of time causes the needle to be
held stationary, and whilst it is so held the clockwork raises up to the
needle two levers, which cither come into contact with the needle or not,
according to the position in which the needle is standing. If the current
is at the strength at which it is desired to maintain it the two levers in
rising pass one on either side of the needle, but if otherwise one or other
lever comes against the needle and is so moved, and the motion is con-
municated to the gas or air valve, and at each action the valve is shifted
through a small space. One lever operates to close and the other to
open the valve.

page_text: Fifth. Automatically regulating the strength of the current, sub-
stantially as described.
In witness. whereof, I, the said Charlton James Wollaston, have
.hereunto set my hand and seal, this Sixth day of July, in the
year of our Lord One thousand eight hundred and seventy-five.
CHARLTON J. WOLLASTON. (L.S.)