IMPROVEMENTS IN HEATING
Year: 1851

page_text: LEDRU'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HECTOR
LEDRU, of 28, Faubourg Poissonnière, at Paris, in the Republic of France,
Civil Engineer, send greeting.
full
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-fourth day of
Marchi (One thousand eight hundred and fifty-one), in the fourteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Hector Ledru, my exors, adiñiors, and assigns, Her especial license,
power, sole privilege and authority, that I, the said Hector Ledru, my
exors, adiñiors, and assigns, or such others as I, the said Hector Ledru, my
exors, adññiors, or assigns, should at any time agree with, and no others, from time
to time and at all times during the term of years therein expressed, should and
lawfully might make, use, exercise, and vend, within England, Wales, and the
Town of Berwick upon Tweed, my Invention of "IMPROVEMENTS IN HEATING;"
in which said Letters Patent is contained a proviso that I, the said Hector
Ledru, should cause a particular description of the nature of my said Invention,
and in what manner the same is to be performed, by an instrument in writing
under my hand and seal, to be inrolled in Her said Majesty's High Court of

page_text: Chancery within six calendar months next and immediately after the date of.
the said in part recited Letters Patent, as in and by the same, reference being
thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Hector Ledru, do hereby declare that the nature of the said Invention, and in
what manner the same is to be performed, are fully described and ascertained
in and by the present Specification, reference being had to the Drawing here-
unto annexed, and to the figures herein contained, in which the same letters
of reference indicate in the three first figures parts which are similar, that is
to say:-
My Invention consists in certain new combinations of apparatus for heating,
by which a circulation of air is obtained to and fro' against the fire chamber or
furnace and the conduct pipes of the flame and smoke, but in an inverse
direction, by which means all the caloric of the combustible is utilized. Expe-
rience has demonstrated to me that it was a necessary condition for a good
heating apparatus that cold air should be made to enter and rub against the
lower extremities of the pipes through which the smoke escapes. It is at that
point that the air begins to be heated (by its friction against the pipes, to the
temperature of the burnt air lost in the chimney, from which it completely
exhausts the caloric. The air then continues its course, always in an ascending
direction, along the pipes, and always in a contrary direction to the current of
the flame and smoke, and finally arrives against the upper chamber or recess,
when the air completes its heating by rubbing against that recess; which is the
hotest part of the apparatus, and thus becomes saturated with the whole of the
caloric disengaged from the combustible. The air so heated is conducted, by
means of pipes adjusted to the upper part of the apparatus, to the places which
are to be heated.
Figure 1 is a vertical elevation passing through the center of the apparatus.
Figure 2 is a horizontal section through the line A of Figure 1.
Figure 3 is
a horizontal section drawn through the line B of Figure 1, and Figure 3 is a
front elevation of the apparatus.
In Figures 1, 2, 3, and 4, A represents the place where the fire is made; it
is of cast iron. B is a discharge pipe for the smoke and heated gases. C, cast
iron or sheet iron top recess, within which the smoke and heated gases expand.
D, D, D, iron pipes communicating from the top recess c to the lower recess E.
The smoke circulates from top to bottom within the pipes D, D, D, and from
the recess E it escapes into the atmosphere through the smoke pipe F. The
number of the pipes D, D, D, is unlimited, and is proportioned to the diameter

page_text: of the apparatus. G is an 'internal iron cylinder or casing surrounding the
part A, and serving to neutralize the effect of the radiation of the fire on the
pipes D, D, D; the cylinder G. besides produces a current at the central part,
and causes the equililibrating of the temperature of the whole of the air which
escapes by the opening H. I, masonry envelope surrounding the apparatus;
it is constructed with bricks, and its separation from the apparatus transmitting
the heat is not any impediment to the expansion of the several metallic parts.
Some suitable holes are made at the lower part of the masonry work for the
introduction of the air to be heated. When the atmospheric air is introduced
through an under-ground channel, having its ingress under the recess E, the
above described holes are suppressed. The recesses C and E are provided
with stoppers, which can be removed when the cleansing is to take place.
The air required for the combustion is taken from the basis of the ash-pit,
and a slide or register regulates the necessary quantity. The door of the
furnace is provided with a hole to facilitate the combustion of the unlighted
gases. The arrows set in red ink represent in Figure 1 the course of the
smoke and heated gases. The arrows set in black ink in the said Figure 1
represent the circulation of the air to be heated, which is discharged through
the opening H at a mean temperature of seventy degrees centigrade; that
temperature may be varied according to the effects to be produced. One of
the essential parts of this new apparatus consists in conducting the products of
combustion under the cinder pan so as to permit an equal quantity of burnt air
to be carried off by the vertical pipes D, D, D. This result is obtained by
the pipe F, through which the burnt air proceeds into the chimney. This pipe
takes up the air from the very centre of the lower recess E; to insure unformity
of egress for the burnt air through the pipe F, which could not be obtained if the
pipe took up the air from one side of the said recess B, as in that case the pipe
D, D, D, nearest to the mouth of the. pipe F, would permit. the egress of a
larger quantity of burnt air than the most remote pipes from the said centre E;
in that case the result would be that the surfaces presented by the pipes D, D, D,
would not produce all the necessary calorific effect; that is, they would heat a
smaller quantity of air.
An important feature of my Invention consists in having a small grooved
opening, the size of which may be regulated at discretion; it is made in the
door of the furnace, for introducing fresh air into the current of flame and
smoke which have escaped combustion; by that means much caloric is saved
which otherwise would be lost in gas and smoke. The internal cylinder or
casing G stands about eight or ten inches above the lower recess E, in. order

page_text: to permit a part of the cold air to enter the bottom of the apparatus in the
direction shewn by the black arrows, and rub against the furnace, in order to
cool it and prevent its becoming red hot; the air thus heated escapes at the
top of the apparatus through the opening II, which conducts it, by means of
pipes, into the places to be heated. The apparatus being elongated to the
upper recess c enables coke to be burned, which is introduced through an
opening in the top of the apparatus, a little below the recess C. All the pipes
D, D, D, may be suppressed, but in that case an opening is made above the
recess C, through which the smoke proceeds direct into the chimney.
It will be easy to perceive that this new combination of apparatus, the
essential part of which consists in obtaining a very large surface and a good
circulation, in order to heat a considerable quantity of air, effects the saving of
all the caloric of the combustible, and produces all possible effect from the
caloric. The apparatus is so combined as to permit frce dilatation of all its
parts, by which I protect the iron parts composing it from breaking, and.
insure a long duration to the apparatus without necessitating repairs.
Another important improvement relating to the mode of cleaning the heating
apparatus is represented by Figure 5. It consists of a tube R, through the
interior of which a cord S is passed; to the extremity of the latter a ball V, or
mud brush, is suspended, having a diameter of a dimension similar to that of
the interior of the pipes D, D, D, Figures 1, 2, and 3, which is to be cleaned.
If a brush be employed it should be loaded with lead or other heavy metal, to
precipitate its descent into the pipes D, D, D. The sweeping tube is provided
with a small socket, into which a candle or torch is fixed for the purpose of
giving light whilst cleaning. The cleaning tube is introduced through the
opening into the upper recess C, and the ball is made to slide down alternately
each of the pipes D, D. D, by means of the weight U and cord V, as far as the
lower recess E; the passage of the said ball into the pipes D, D, D, detaches
the soot clogged to the internal sides of the pipes, and it falls into the lower
part of the said recess E, to be withdrawn through the opening T.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I wish it to be under.tod that I do not
confine myself to the precise details of the apparatus or of the modus operandi
herein laid down, provided the general features be preserved; nor do I lay
claim to the several parts of the apparatus taken separately; but what I do
claim as my Invention intended to be protected by the sail Letters Patent is,
firstly, the combination of mechanical apparatus for causing air to travel against
the furnace and conduct pipes of flame and sınoke, for obtaining and applying

page_text: all the useful effect of the caloric, as herein-before described in reference to
Figures 1, 2, 3, 4. Secondly, the apparatus for detaching the soot collected in
the flues of the furnace, as herein-before describe in reference to Figure 5.
In witness whereof, I, the said Hector Ledru, have hereunto set my hand
and seal, this Eighteenth day of September, in the year of our Lord
One thousand eight hundred and fifty-one.

page_text: AND BE IT REMEMBERED, that on the oath of William Armand Gilbee,
the Specification aforesaid was eurolled word for word as above written. And
also the Specification aforesaid was stamped according to the tenor of the
Statute made for that purpose.
Enrolled the Twenty-fourth day of September, in the year of our Lord One
thousand eight hundred and fifty-one.