AN IMPROVEMENT IN HEATING OR COOLING AERIFORM AND LIQUID BODIES
Year: 1855

page_text: LETTERS PATENT to Theodore: Schwartz, of the City and State of New
York, in the United States of America, now of No. 67, Gracechurch
Street, in the City of London, for the Invention of "AN IMPROVEMENT IN
HEATING OR COOLING AERIFORM AND LIQUID BODIES."
Sealed the 4th March 1856, and dated the 6th September 1855.
PROVISIONAL SPECIFICATION left by the said Theodore Schwartz at the
Office of the Commissioners of Patents, with his Petition, on the 6th
September 1855.
I, THEODORE SCHWARTZ, of the City & State of New York, in the United
States of America, now of No.67, Gracechurch Street, in the City of London,
do hereby declare the nature of the said Invention for "AN IMPROVEMENT IN
HEATING OR COOLING AERIFORM AND LIQUID BODIES " to be as follows:-
It consists in enlarging, according to the nature of the case, either the
external (absorbing) surface or both surfaces (absorbing and discharging) of
the receptacles of heat or cold for operating upon liquid or ueriform bodies.
This enlargement is accomplished by producing raised or protruding surfaces
on the usual plain or smooth surfaces, in the form either of grooves, ribs,
tidges, projecting edges, blades, rings, flanges, points, or other protuberances '
or indentations, whereby the agent employed for heating or cooling will have
greater action & power to effect its object within a given time than when
acting as usual on the plain surfaces. The details of my Invention will be
fully described & illustrated by Drawings in my final Specification.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Theodore Schwartz in the Great Seal Patent Office on the
6th March 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THEODORE
SCHWARTZ, of the City and State of New York, in the United States of
America, now of 67, Gracechurch Street, in the City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of September, in the year of our Lord
One thousand eight hundred and fifty-five, in the
year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Theodore Schwartz, Her special licence that I, the said Theodore Schwartz,
my executors, administrators, and assigns, or such others as I, the said
Theodore Schwartz, or my executors, administrators, and assigns, should at 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 Invention for" AN IMPROVEMENT IN
HEATING OR COOLING AERIPORM AND LIQUID BODIES," upon the condition (amongst
others) that I, the said Theodore Schwartz, my executors 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 Inven-
tion, 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 Letters Patent.
NOW KNOW YE, that I, the said Theodore Schwartz, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement :-
The nature of my Invention consists in increasing the action and efficiency
of the agent by which heat or cold is produced in liquid or aeriform bodies, by
constructing a protruding or raised instead of a smooth surface, or, in other
words, by enlarging the external surface or both the external and internal
surfaces of the receptacle, by producing on the usual plain or smooth surface
raised or protruding surfaces in the form of grooves, ridges, ribs, projecting
edges, blades, rings, flanges, or other protuberances or indentations.
It will be necessary to enter into details respecting the principles upon
which the improvements are founded, as they are not generally understood, to
point out the prominent uses to which the improvements may be applicable,

page_text: and also to describe the modes of constructing the surfaces. For the sake of
clearness the description is divided into three parts:-
First, heating and cooling aeriform and liquid bodies is generally effected
through the mediation of a receptacle, such as a cooking vessel, boiler, &c., in
which case thegenerating or absorbing surface which receives, and the radiat-
ing surface which transmits and discharges, the heat or cold, or, in other words,
the outside and inside surfaces of the receptacle, have different and opposite
duties to perform; hence, the consideration arises as to what may be the
relative capacity and efficiency of each for the performance of its specific
object. The general practice in this respect is to make the two surfaces as
nearly alike as circumstances will permit. Many experiments and a careful
investigation of the subject, have convinced me that this practice is erroneous
when bodies of different: densities, or bodies of the same density acting at.
different velocities, or under other different circumstances, are in question. For
example, when the body to be heated is a liquid and the heating body is
aeriform, the liquid being of greater density receives the heat from the beated
surface more readily than it is imparted by the aeriform and less dense body;
and therefore to produce the greatest effect with the same current of heated
air, the surface with which it is in actual contact should be greater in propor-
tion than the surface which is in contact with the liquid body. Thus, also,
when the object is to cool an aeriform body by the application of a liquid, the
surface with which the liquid is in contact should be smaller in proportion
than the surface with which the aeriform body to be cooled is in contact, and
so also when the bodies are of the same density, and one is in motion and the
other comparatively quiescent, the latter requires a greater surface.
In reducing these principles to practice, it should not be supposed that the
increased surface will necessarily be attended with a corresponding increase of
effect, as each application presents counteracting and neutralizing causes,
which operate independently of the above considerations, and oppose limits in
the transmission of heat in no way affected by the form imparted to the surface
of the receptacle; for instance, the amount of the heat to be communicated
within a given time may be but equal or even inferior to what a plain surface
is capable of receiving, or it may exceed the utmost extent which the material
of the receptacle is capable of conducting, in either of which cases the auginen-
tation of surface would produce no increase of effect; or the nature of the
case may be such that the heating agent will present a cooled strata towards
the surface of the receptacle, and by which the heat of the main portion is held
off,.so as to be rendered ineffective; or the velocity of the heating current or
of the body to be heated may be incommensurate to the amount of heat to be

page_text: communicated or abstracted; finally, the doubling or trebling of the surface of
a receptacle by protuberances would not under any circumstances produce a
proportional augmentation in the heating, because the temperature abstracted
from the agentin its first action causes a progressive decrease in its subsequent
power.
The modification of the surface by protuberances as proposed not only
contemplates to increase the effect in respect to the heat imparted or ab-
stracted as compared with plain surfaces, but also to increase and concen-
trate the amount of surface within a given space, and as the ridges or ribs
have two available sides and afford great lateral strength, their introduction
ecouomises material.
Parallel projecting surfaces at right angles with a flat surface, made in the
manner herein indicated, and placed at a distance from one another (measuring
from centre to centre of their thickness) equal to their height, contribute a
surface equal to twice that from which they project, making the whole surface
thus obtained three times as great as the original flat surface.
In respect to the dimensions to be given to the protruding surfaces or ridges,
every purpose to which they are applicable is likely to present considerations
pertaining to the object to be attained or liabilities to be guarded against, each
constituting so many separate conditions to be realized by the form and size of
the surfaces adopted; moreover, the size will depend on the amount of action
that may be expected. On vessels used in the heating of fluids, and which are
exposed to a strong direct fire, the ridges may be made to project up to half an
inch, or or thereabout, at a minimum thickness, varying from one thirty-second
part of an inch at their outer edge to two or three times that much at their
inner edge, and where they are exposed to a less intense heat, as also when it is
expedient to bestow a greater thickness, they may be made larger. However,
numerous experiments have shewn me that comparatively minute dimensions
will be most advantageous, as otherwise the action of the outer portion is liable
to be weak and unprofitable. I think the ridges would be very effective made
from one to three-sixteenths of amiuch high, at two to five-sixteenths distance
apart (from centre to centre of their thickness), upon metal about one-sixteenth
thick. The distances between the projecting surfaces are by no means indif-
ferent to the result, as it should be observed that there is a point at which the
spaces contained between the ridges become insufficient to furnish the requisite
amount of heat without a greatly increased current; for example, ridges of
one-eighth of an inch in height, which are effective when a space of one-fourth
of an inch is left between them, are nearly useless if the space between them
is reduced to one-eighth of an inch.. The general direction of the protruding

page_text: surfaces should be parallel with that of the current applied to them, and,
whenever practicable, they should be slightly inclined against it in such a
way as to compel'anincreased contact with it by opposing its progress. These
conditions, however, are only of importance in proportion to the power of the
draught actuating the fire; for instance, projecting ridges applied transversely
to an intense current would in any case be found nearly useless, while with
an ordinary draught the direction of the ridges is comparatively unimportant.
In actual contact with so as to cover burning coals, a protruding surface, on
account of its more intense absorption of heat, is liable so to weaken the fire as
materially to impoverish the combustion, thereby counteracting the advantage
due to the increased surface. This liability, however, is remedied by slightly
elevating the surface just sufficient for the fire to burn freely under it, a con-
dition to be realized in all cases, particularly with smoky coals, the tar-like
gases of which, by becoming condensed on the surface of the receptacle, form
an isolating coat. We propose to use the protruding or raised surfaces at the
same time on opposite sides or surfaces of the vessel containing the body to be
heated or cooled, whenever the body to be heated or cooled, and the agent
employed to produce the result, are both liquid or both aeriform, neither being
in a quiescent state.
Figure 1 represents, in section, (and, for clearness, upon a scale four times
larger than the working size,) ridges, which experience has shewn to be
suitable and advantageous for steam boilers, heating and evaporating pans, and
cooling apparatus.
Second, the manufacture or constructing of the protruding or raised surfaces
may be effected in all kinds of material applicable for the purpose by casting,
moulding, drawing, pressing, stamping, raising, glass blowing, grooving, or
cutting the material of which they are composed, or by making the projections
of separate material,and then attaching them to the ordinary surface by solder-
ing, brazing, casting, dipping, coating, welding, shrinking, pressure-jointing,
rivetting, or by using any other of the known mechanical means of fastening
one body to another when both are to be exposed to heat.
Forming projecting surfaces on metal presents in certain cases particular
difficulty, in view of which the following practical devices are suggested,
to wit:-
Process to facilitate the Manufacture of Metallic Tubes with Transversal Ridges.
It is proposed to use plain tubes, and to execute the ridges separately in the
form of flat rings in the most convenient way; taking care that they fit exactly
on the outside of the tube to which they are to be attached, and their fastening'

page_text: is to be effected by slightly dilating or expanding the tube. To fix the rings
readilyat theirproperdistances apartwithoutconnectingthem, threediminutive
ears may be bent up from the inside periphery of each. It is presumed that
therings thus fastened will be not less efficacious than those soldered or brazed,
and will be cheaper than when cast or cut solid, even supposing they were cut.
continuous in the form of a screw thread. Figure 2 represents a piece of tube
(fullsize)applicable to steam boilers, with rings, according to the above process;
Figure 3 shews a similar piece, with the ridges formed like a screw thread ;
Figure 4 has longitudinal ridges inside, such as may be produced by the draw
plate; and Figure 5 shows the same kind of projections applied outside of the
The principle suggested for this purpose admits of two modes of application,
namely:-
First mode. The wire ridge (a) is formed in section, as represented in
Figure 6, of quadruple size, having a groove in the edge, by which it is to be
fastened, and is lodged in an exact fitting cavity of a depth just sufficient to
admit it flush with the grooved edge, the receiving cavity being hollowed out
in the face of a die, metal block, or other appropriate tool (b).. The wrought
metal (c), to which the wire is to be attached, being held against the wire, a
depression is effected on its opposite side by means of a delicate steel edge (d),
which forces (or raises) a corresponding small projection into the groove of the
wireedge, and thereby accomplishes the clenching of the metals, making the
wire perfectly fast to the wrought metal pressed against it. The steel edge
used, as just stated, to produce the clenching depression, should be somewhat
thinner than the groove of the wire, and it may be executed more advan-
tageously in the form of wire countersunk in an appropriate receiving surface
than by being chased up in solid metal.
Second mode. Instead of forcing the wrought metal into a groove in the
wire ridge to effect the jointure, the ridge may be locked ina groove formed in
the metal, which amounts to using the same means in reverse order. To form
the required groove in the metal (a), Figure 7; two tools are necessary;
one (6), having a slight projection of the size to produce the groove itself, and
the other (c), with a cavity somewhat wider than the said groove, and the
object of which is to prevent the wrought metal from spreading in pressing the
groove by confining it, the hollow tool being-placed on the opposite side for
that purpose. The wire ridge (a), Figure 8, to be fastened, is lodged in a
cavity, the same as in the previous case, but may be allowed to project very

page_text: slightly, and the edges (b) of the cavity itself are required to project beyond the
surface in which it is formed sufficiently to perform the clenching operation,
which is accomplished solely by their means, the groove of the metal (c) being
made to pinch the wire so as to become fastened to it by the application of the
requisite pressure.
The above two methods for fastening wire ridges are especially applicable
to ready-made culinary vessels of copper, brass, tin plate, or other malleable
metal, and in a variety of ways to many kinds of surfaces for similar uses.
Process for Raising by Pressure, Projecting Surfaces on Wrought Metal.
First process. This purposes to raise hollow projectious by stretching or
extending the metal, not by the mere bending, as in what is usually called
corrugating in this case the cohesion opposes itself to carrying the form
beyond certain limits, varying according to the manner of working; and in
order to accomplish the utmost that the metal may be made to bear, it is
proposed to operate as follows:-First, having raised projections in the usual
way, of a form (as represented of double size in a, Figure 9,) most readily
imparted, rest the metal (a) thus shaped, one side against the face (b) of an
appropriate bearing surface, the hollows on the opposite side being filled level
with some ductile material (c) like lead, and complete the forming of the
projections, by producing on said opposite side a displacement in the ductile
material by and through the pressure of a die or other suitable tool (e), applied
as represented in the Drawing. Figure 10 represents the ultimate form to
be approximated to by the projections formed under this process.
Second process.-This is applicable only to heavy metal, and consists in
forming what may be termed consolidated or cohesive corrugations (as in
Figure 11), by limiting the depth of the hollows (a, a, a,) to something less
than the thickness of the metal (b, b), avoiding to traverse the entire thickness,
in order to leave unbroken so much of the plain metal as may be required to
retain a certain amount of transverse strength. The object in thus forming
hollow projections is to combine with the lateral and transverse strength of
plain ridged metal (like Figure 1) the facility of making by corrugation.
This principle is applicable to plain surfaces and tubing, and, in fact, to metallic
plate of any form.
Metal formed with hollow projections, as in the foregoing two processes, or
generally presenting narrow cavities on one side, of the character of folds,
may be rendered smooth on that side, when desired, by soldering, welding,.
enamelling or other binding coating, or by filling the cavities with suitable
material.

page_text: This system of filling and closing hollow projections render them applicable
in cases when one side of metal is required to be smooth.
Third, the Invention is more or less applicable, and I contemplate its use
for the following purposes, namely, steam boilers, evaporators of all sizes,
from the vacuum apparatus, sugar pan, and salt boiler, down to the simple
evaporating dish; surfaces for drying and rarifying steam and gases, coolers,
condensers, and refrigerators, stills, heating pans and boilers for brewers, dyers,
hatters, and analagous uses, domestic cooking and buking vessels.
The Drawings hereto annexed are herein referred to, and made part of
the foregoing Specification.
Having thus described the nature of my Invention, and the manner of using
the same, I claim,
First, the processes herein described for making tubes with transverse ridges,
for attaching wire ridges or other protuberances to wrought metal, and for
projecting surfaces to wrought metal.
Second, I do not clain the use of the protruding or raised surfaces for the
purpose of discharging or radiating heat on the outside of stoves.and.hot air
furnaces, as that is not new, nor do I claim the use, of.or for. steam boilers, of
the article generally known under the name of corrugated iron, nor of any
.description of corrugated metal or other material which may have been used
for increasing heating surface. I also disclaim the use of boiler-plate iron
rolled with solid projecting ridges or ribs, and of metal of any kind applicable
in the heating of liquids having heat-conducting points, pins, rods, or canoidal
protuberances applied endways to or traversing its surface or surfaces. With
these exceptions, I do claim as my Invention the use and construction of
protruding or raised surfaces of the description herein above set forth, for the
purposes of absorbing and of conveying heat, in accordance with the principles
and for the objects herein above referred to, substantially as above described.
In witness whereof, I, the said Theodore Schwartz, have hereunto set
my hand and seal, this Sixth day of March, in the year of our Lord
One thousand eight hundred and fifty-six.
THEODORE SCHWARTZ. (L.S.)