AN IMPROVED CONSTRUCTION KETTLE
Year: 1884

page_text: This Specification was, upon the 25th day of June 1886, amended under
Sections 18 to 21 of the Patents, Designs, and Trade Marks Act, 1883.
TA
L
I DAVID HARRY SHUTTLEWORTH BROWN of 5 Huggin Lane Queen Victoria
Street in the City of London, Engineer, do hereby declare the nature of my
invention for AN IMPROVED CONSTRUCTION KETTLE to be as follows:-
The object of this invention is to construct a kettle with a large and efficient
heating surface, coupled with a small radiating surface, with provision for protecting'
the hand from the danger of scalding from the escaping steam, for facilitating the
discharge of the water in respect of quantity and direction and providing a test for
indicating that the boiling point is reached.
The body of the kettle I form of a half sphere closed at bottom by a plate having
radial corrugations by preference angular in cross section and inclining towards the
centre of the plate. The opening in the kettle for admitting liquid thereto instead
of being in the centre as heretofore and below the handle is situated in rear of the
handle and a curved shield standing up from the top of the kettle bends rearwards
over the opening for the purpose of forming a support for the rear end of the
handle and shielding the hand of the user of the kettle from the steam escaping
from under the lid it serve also to retain the loose lid in place when the kettle is
tipped for pouring.
The forward end of the handle is secured to the spout of the kettle which is
raised somewhat higher than usual. The handle is bent down in front to reach the
support and it thus facilitates the discharge of the boiling liquid both as respects
the direction and quantity of the discharge. The lid fits loosely in place but so as
to prevent a free escape of steam. When a pressure of steam due to the liquid'
baving reached the boiling point acts upon the underside of the lid a tremulous'
motion of the lid will occur producing an audible indication that the boiling point
is reached.
The handle of this kettle may be made of wood or other non-conductor of heat,
the body of the kettle I prefer to make of white metal and the corrugated bottom
of sheet copper.

page_text: I, DAVID HARRY SHUTTLEWORTH-BROWN of Belle vue Villa, South Wimbledon
in the County of Surrey, England, Engineer, do hereby declare the nature of my
invention for AN "IMPROVED CONSTRUCTION OF KETTLE" and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
The Kettles, now generally in use have the smallest possible heating surface
combined with the largest practicable radiating surface, and the handles are so
constructed as to burn the hand that grasps them and are so placed that when the
water boils the steam issuing from the lid scalds the hand, which, being over the
centre of the kettle is so far from the orifice of the spout, that it has no control
over the liquid it would discharge, the quantity and direction of which, is subject
to the slightest oscillation, if the kettle is full, and is canted forward the water
escapes from under the lid and runs down the front of the kettle instead of being
poured out of the spout, if it is nearly empty the lid falls out, and may burn the
knuckles, break the china roll away and be lost and when found may be damaged―
if the kettle is not quite emptied and is taken to the tap, it is awkwardly arranged
for the admission of the tap, for which room has to be found under the hand, and
as cold water runs in, scalding vapour rushes out, and envelopes the hand, because
the lid, inlet orifice, or manhole, or rather hand hole is entirely under the hand-
and though it hardly ever happens that two persons meet who agree as to when a
kettle boils" the kettle itself is not provided with any indicator, and either the
lid is so light and loose that it rattles as the saturated air within it is being
expanded, and escaping while the water is only warm or elso it is so tightly
wedged into the hand-hole that this mere expansion of the air forces tepid water
out of the orifice of the spout which is so little above the level of the water in the
kettle that sometimes it runs out of the spout even when, it is not projected by the
tension or expressure of this air, in the kettle, but on account of the sheer expansion
of the water itself-and lastly the kettles now generally in use are not adapted
either to the height of the arm or to the muscles of the hand.
"
The object of this invention is to correct the defects, and to supply the deficiencies,
of the kettles now generally in use and to construct a kettle with the largest and
most efficient, heating surface practicable combined with the smallest radiating
surface possible and with provision for protecting the hand from burning through
the heat of the handle, or of the knob of the lid, as well as from the danger of
scalding by the escaping steam, for facilitating the discharge of the water and
controlling it in respect of quantity and direction,with provision for preventing
the lid, if unattached by a hinge, from falling off, and for the convenience of filling
the kettle by the. hand hole when it already contains some water in a state of
active vapourisation (without foregoing the easy means of inspection scale removal
and ropair) with provision also for indicating that the boiling point is reached and
for avoiding any harmful projection of water from the orifice of the spout whilst
the kettle is well adapted to the height of the arm and to the muscles of the band.

page_text: The Heating Surface is made as large as practicable by corrugating it, and is
most efficient when corrugated radially to a degree suited to the nature and³
intensity of the source of heat, and when made of a metal that is a good conductor
and has a low Specific Heat-As to conductivity the best known substances are
said to compare thus Copper 897, Iron 374, Porcelain 12, or thus-Silver 100,
Copper 73, Iron 11.9.
As to Specific Heat, referred to Water as 1.0, Copper 0324, Silver 0571,
Iron 114 or thus, Cold hammered Copper 0934, Wrought Iron '1112, Cast
Iron 2411.
22
7
The Heating Surface may be increased by half its area when the corrugations
are such that a + b = c, sco Diagram No A 1, in which a and b are sides of the
corrugations and c the distance between them and such a surface may be made by
hand thus, Suppose the Kettle requires to be 8" diam its circumference will
be 3 (8") or (8") or 4th of the diameter will bend of the circumference,
take now a circle, and divide its circumference into 22 parts of or 1" each
each part will represent two sides of a corrugation a + b. Cut out one quarter of
the circle and divide each of the 22 parts into two and bend the plate radially at
The divisions till the circle has become a corrugated half circle, treat another
circle in the same way-braze the two together—and a beating surface has been
formed of two circles i.e it has the area of a circle and a half, its circumference
is 27" it contains 33 corrugations, having 66 sides, which beginning at zero in the
centre become " wide at the periphery, with a circular distance of " between
them whatever the diameter of the circle, 4th as a divisor will give the same
angles to the corrugations,—the same result could be obtained by constructing a
hendecagon in tho usual way, and bisecting its chords to obtain the 22 parts of the
circumference the area can be made greater or less by making the handles of the
corrugations more or less acute, and by using more or less of the circles to make
the surface, the sides of the corrugations can also be made wider or narrower i.e.
deeper or shallower by dividing the circumference into a less or greater number of
parts.
The following formula will enable anyone to construct a heating surface of any
diameter, of any ratio to the area of a circle with the same diameter and with any
depth to the sides of the corrugations at the periphery and will determine the
number of sides of, and the distance between, the corrugations.
Let a =
diameter, b = ratio of heating surface to area of circle with diameter a,
and let c = depth of side of corrugation, at periphery.
Then
23 ab
7
•
= number of sides of,
and = distance between, the corrugations.
Thus steel dies for stamping the corrugations to any degree of acuteness the
metal will bear can be easily constructed, but the absorbing power varies with
the inclination of the incident ray, being greatest at the normal of incidence,
therefore the amount of radiant heat absorbed is not proportional to b,—the nature
and intensity of other kinds or sources of heat, likewise limits b and c, as will be
shewn When it is desirable to prolong the action of the source of heat, as by
retarding the escape of any given portion of the products of combustion, the radii
of the corrugations may be curved or waved heating surface mado upon the

page_text: If the kettle is to be heated on an iron kitchen range the centre of its heating
surface may be made level with the furrows of the corrugations of the periphery,
the radial lines of these furrows will thus be in contact with the hot plate of the
range along their whole length and be acted upon by conduction, there will be no
thorough draught and the sides of the corrugations will be acted upon by unimpeded
radiation, at a minimum mean distance.
If the kettle thus constructed is to be heated on a gas stove or Bunsen burner
the Aqueous Vapour, which is one of the products of combustion and condenses on
the bottom of a kettle, (until it has slowly acquired such a temperature as to
become capable of absorbing such an amount of heat that condensation is no longer
possible) will, in case the coldness of the water should create excessive con-
densation, run down to the bottom edges of the corrugations, and will not have to
be all boiled off the surface as is usual, but will be again vapourised as it hangs
down in drops from the angles of the corrugations, the sides of which it cannot
here continue to cool during its revapourisation, and where the heat it is subjected
to is proportionally more intense,--thus the heating surface would become dry at
an carlier period than if it were flut, and during this difference of time a honting
surface, the extent of which is represented by the ratio b is being acted upon by
the whole heat of the flame, instead of a surface represented by 1 or the ratio
by the small amount of heat which can be transmitted through the liquid film of
condensed vapour, and which, on account of revapourisation, must be something
less than 212° F.
1
It is said that if air has full access to fuel all the carbon will burn to carbonic
acid CO, and all the hydrogen to water H₂O as the oxygen of the air combines
with the carbon and free hydrogen of the fuel-and of Coal Gas, that nearly 50%
consists of hydrogen, and the rest is nearly all carbon combined in one way or
another with hydrogen-that during combustion those gases are intimately mixed
with the air in the Bunsen flame, therefore during this time their relative densities
(although they vary as 1 to 8 or even 14) can not affect their relative positions in
the flame. Now while the aqueous vapour, produced by combustion is being
condensed on the bottom of the kettle there is an active movement among the
molecules which constitute the different resultant gases that are being produced by
a process of selection, and of these, a part viz:-this aqueous vapour is being
reduced in volume by as much more (or less) than 1700 times, as the difference
between the temperature of the flame and that of the condensed water is more
(or less) than the difference between 0° and 100° C-this condensation involving
an immense and instantaneous change of volume tends to produce a vacuum into
which the resultant gases tend to effuse, now the force or rate of diffusion or
etlusion of different gases is said to be inversely as the squaro roots of their
densities, the density of CO, is said to be 15290, and that of aqueous vapour 6225,
(but that of the mixed gases which produce aqueous vapour is only 4147) that of
air, thus, I assume that the aqueous vapour has a greater tendency to rise into
contact with, or impinge against the cold surface of, the bottom of the kettle than
the CO, and that if the heating surface be thus constructed viz-with its centre
lower than the ridges of the corrugations, these latter having an upward tendency,
will favour the escape, of soine at loast, of the aqueous vapour disengaged during
combustion which would otherwise condense (and require to be revapourised) on
the bottom of the kettlo if it were domed, as it is now the practico to make what
is called a "Bachelor's Kettle" to prevent "popping."
The beating surface thus constructed divides tongues of flame by wedges of
water-there is perhaps no limit to the advantage of making the angles of the
wedges of water as acute as they can be mado but there is a limit which cannot
well be exceeded in the corresponding angles imparted to the tongues of flame-
the depth of the corrugations gradually increases from the centre towards the
periphery, and this finds a coincidence, in the heat of the Bunsen flame which
increases from the centre towards the periphery, and this coincidence enables these

page_text: angles to be more acute, than if it were otherwise, but they cannot be so acuto
that the flame would be subdivided by cold metal, to such an extent as to be
cooled till its combustion is impaired by the production of lower oxides, or
extinguished.
The advantage of a heating surface so constructed as to perinit of the early
formation and rapid rise of steam bubbles may be due to the specific heat of steam
being relatively lower than that of water (it is said to be as 4805 to 1) as well as
to the circulation or convection promoted by the rise of the steam when it is being
condensed by the water, if so, the value of the low specific heat of steam is of great
importance in the furrows of the corrugations, the water is presented in detail,
and as the point of a wedge to the action of the flame on both sides of it, the edges
of the furrows become superheated points or rather lines and their power of con-
duction is (not proportionally) but in a given proportion increased-the steam is
formed early here, and its low specific heat yields advantage, but the more
advantage the more rapidly it can rise, if steam is formed upon the sides of the
corrugations, it rises without impediment, if on the ridges, its rise is accelerated
by the conditions of its position-assuming that the specific heats given above
apply weight for weight, the advantages of early formation and rapid rise of steam
bubbles are obvious and important, the disadvantage arising from the lingering of
steam bubbles on the heating surface is due to the inferior power of an attenuated
vapour to absorb an amount of heat which might have been imparted by the plate
to the water, which has therefore not been transmitted, and to the diminution of
the power of the plate to receive or absorb heat as its temperature approached that
of the flame-Different explanations are given of the action of different materials
for heating surfaces, which it is said is not properly understood, smooth surfaces
are said to retard the formation and rise of steam bubbles relatively to rough ones,
and glass relatively to metal surfaces, it is also said that if a piece of metal bo
thrown into a glass vessel ebullition, which is retarded by the nature of the
material or surface of the vessel, will commence, also that if pieces of glass,
granulated zinc, or tacks be thrown into a vessel, ebullition will be accelerated, the
bubbles forming on, and rising from the angularities of the pieces-hence an
advantage in the corrugated heating surface the explanation of which appears to
be this..
A particle of water perhaps in contact with a point on, or above a pore in, the
plate of a flat bottomed kettle, is superheated, or it contains a trace, a molecule
of air in solution and so it is selected to be converted into steam-and as rapidly
as the superincumbent pressure will permit, it enlarges to 1600 or 1700 times its
own bulk it tends to enlarge in every direction, it cannot enlarge downwards, on
account of the resistance of the plate, but only upwards and laterally-therefore it
tends to form a hemisphere the base of which is lying on the plate, now if this
hemisphere, this bubble of steam, could be imagined to have a corrugated bottom as
this kettle has, it would probably rise immediately but it has not, and it has taken
this form on account of the equal resistance which it met (during its formation) in
the vertical and statical pressure of the superincumbent liquid,-at any point of time
while the bubble was expanding and before it had attained its maximum dimensions,
it was under pressure inversely proportional to its volume and its heat was pro-
portional to the pressure (the pressure measurable by the momentum imparted to
the particles of superincumbent water)-the particles of the water which resist the
pressure of the nascent bubble are affected by its heat first on that side on which
they receive it (now it is said that pure water in a state of ebullition is a
phenomenon which has yet to be witnessed) these particles may contain air in
solution which being suddenly expanded tends to rise and causes the particles to
revolve in a direction which for each particle is in a radial line from the centre of
the bubble-the source of heat-a film separated from the inass of quiescent liquid
by its particles having this motion imparted to them lies upon the inclined surface
of the hemisphere and its particles convey the impulse they have received, with
diminishing energy to the particles adjoining them in the mass of liquid and the

page_text: direction of their momentum prevents them from passing under the bottom of the
bubble or hemisphere, the centre of which is in an opposite direction to that of this
acquired momentum-the superincumbent liquid has by its statical pressure to
break through the film (the energy of which approached from without, would be
found to increase in intensity) before it can pass under the bubble, but if the
bottom of the vessel is as smooth as glass there are no breaks in its continuity the
lateral radial force of the expanding bubble has pushed all the liquid before it,
there is no liquid under the bubble, there is no inlet, the activated film of revolving
particles remains unbroken, the statical pressure of the liquid has been defeated
and the bubble adheres to the bottom-If this is accepted it is unnecessary to
explain how steam bubbles formed on the sides of the corrugations rise without
impediment, and how if formed on the ridges, their rise is accelerated by the
conditions of their position-if formed in the furrows ?-the top of the ridge is a
line which has a sensible width, the base of the furrow is a geometrical line.
The acquirement and retention by a particle of water of 5-36 times the amount
of heat which the body of the liquid, in which it exists, has acquired or can retain,
must be due to its being cut off by such a revolutionary motion as that ascribed to
the particles constituting the film encompassing the steam bubble, the gases of the
air which it holds in solution are differentially soluble at the temperature which it
has acquired, these gases may be intimately mixed, but ultimately their molecules
must be side by side and thus when one expands more than the other the particle
is thrown out of equilibrium and is caused to revolve by the energy which the
molecule of gas exerts in passing from the liquid or dissolved condition into the
gaseous, it revolves on the point, (not to say the molecular pole, or the geometrical
point, but) the microscopical point on the heating surface which imparted the heat
which disturbed its equilibrium, and continues to receive and absorb the heat of
which the particles that surround it can receive only some, as they too are caused
by it to revolve, but with rapidly diminishing force on account of the proximity of
those on opposite sides of the particle, which revolve in opposite directions to each
other and also of the friction produced by (and therefore tendency to reverse the
motion of particles on any, the same, side of it revolving each in the same
direction (the cause of diminution of revolving force transmitted by the particles of
the film above referred to) it is therefore, being thus surrounded, and, unaffected
by convection, entirely subject to the influence of its revolution on the point from
which it acquires its heat until it has acquired so much that (? burst by centrifugal
force) it is converted into steam-the influence of the nature or material of the
heating surface upon ebullition is here presumptively accounted for.
"
Now as to incrustation or the deposit of scale-it is said that "the tendency to
form scale is the greater, the slower the deposit is laid down-that a portion of
the earthy carbonates is deposited as soon as the water is warmed, another only
after considerable boiling, while some remains in solution even in boiling water
therefore the more effective the heating surface, ie, the quicker the water is boiled
the less the deposit and the greater the area of the deposit the thinner the scale-
the scale deposited on an inclined surface is not so hard as that on a flat surface.
The Radiating Surface is made in the form of half a sphere, which presents,
with other advantages the smallest possible radiating surface (the sphere among
geometrical figures being that which relatively to its contents has the least
possible superficies)-it should be made of a metal that has little power of conduction
if possible combined with little power of radiation.
To diminish radiation the surface is burnished, if it were coated for this purpose,
with a metal of greater density their coefficients of expansion should be as nearly
equal as possible. The heat which this form of radiating surface derives from the
bottom of the kettle or the source of heat can only on account of the shape be
applied to the water from above, in a direction downward, varying with the radius-
which soon becomes a direction in which the water is almost incapable of receiving
heat such heat must therefore be lost by radiation and absorbed by the mountings
of tlie kettle, hence the necessity of the radiating surface being made of a metal

page_text: it for the knob of the lid, and above, and in front of, it for the fingers of the hand
which grasps the handle (fixed and supported by it) from before and which it
protects.
PROVISION for facilitating the discharge of the water and controlling it in respect
of quantity and direction.
The handle of the kettle is fixed to the spout in such a manner that the hand
which grasps it may be brought near to the orifice of the spout from which the
water issues, an arrangement which gives it control of the quantity and direction of
the water it would cause the kettle to discharge, this control is made complete
by the definite angle with the base, at which the lip of the hand-hole cuts the body
of the spherical dome of the kettle in order to determine its level in regard to this
orifice of the spout (from which the water issues) when the kettle is canted.
-likewise the distance B B.
By this means the kettle is so constructed that when the orifice at the issue of
the spout is placed at a definite height above the water level in the kettle, for
reasons to be stated, the water never issues from the lid when the kettle is canted,
but always from the spout over which the hand has complete control.
C
PROVISION for preventing the lid if unattached by a hinge from falling off, should
the water be poured out of the Kettle when it is nearly or until it is quite
empty.
The hood, shield or baffle plate in front of the hand-hole, to the top of which the
handle is fixed in front, rises rearward in a curve and is so arranged that it presents
to the lid a concavity into which it can fall, being immediately arrested by its
knob should the lid tend or chance to fall off its seat or out of the hand-hole
when the kettle is canted forward.
.
PROVISION for of the greatest attainable convenience for filling the Kettle when it
already contains some water of such a temperature that it then assumes a state
of active vapourisation.
The hand-hole, the size of which is not diminished in order that this object may
be attained, is quite accessible to the tap, and a shield, to the top of which the
handle in front is attached, partly surrounds the hand-hole and is curved rearward
to a certain extent over it presenting to it a concave surface whiclr deflects the
scalding vapour which issues from it and protects the hand which is or may be
partly over it, but which is grasping the handle, conveniently snug, in front of the
shield.
The cold water enters the hot water already in tho kettle, and passing through
it, lies on the bottom of the kettle, momentarily displacing and lifting up the hot
water which then lies upon it, ready, momentarily, to vapourise at the surface ; as
the tension of the saturated vapour within the kettle, in the space above, is reduced,
being condensed, by contact with the cold air, carried in by the water, the air and
vapour now mixed within the kettle being hotter than the surrounding air, are
lighter than it and rise in consequence, they are also forced out by the cold water
which is taking possession of the space they filled.

page_text: PROVISION of easy means of inspection scale removal and repair, by a hand-hole so
arranged as to present other advantages.
The hand-hole is large enough. for the admission of light, a hand, or a brazier's
tools, and the edge within the kettle is not tapered inwards, as is usual, but is
recessed outwards, so that, it does not wedge the lid, and so that the hand hole can
be easily withdrawn-the body of the kettle being spherical, a segment of the sphere
proportional to the diameter of, and above the plane of the hand-hole is cut off-
the angle at which it is placed with regard to the base of the kettle has been
defined the effect of this angle is to bring the centre of the handhole behind the
apex of the hemisphere, so that it is not over the centre of the base, and the back
part of it is at a lower level than the front.
It sometimes happens that a kettle is filled too full and then the water becoming
warm, expands, and runs over out of the spout, when it is said to be boiling over
(and it may afterwards really be doing so) and if the air above it has been unable
to escape, it also expands and its expressure forces still more water out of the spout
than would merely run over. Now in this kettle such water would run out from
under the lid, but at the back, and if it were really in a condition to, be boiling
over, the water would merely trickle down the back of the kettle and damp the
fire instead of doing any injury that might arise from water, or boiling water
being forced out of the spout. Water expands in volume 4°. between the ordinary
temperature of the atmosphere and the boiling point.
PROVISION of a Test for indicating that the Boiling point is reached.
The Boiling point is so often defined as 212° F that a misconception of what the
boiling point really is, requires to be removed before it is possible to indicate that
it is reached, the definitions of it are a little various, and though it has been made
available as a fixed point it is as variable as the weather, and changes with the
Barometer to begin with, it does not refer to water, which can be made to boil at
almost any temperature at which it does not freeze, whilst according to the nature
of the vessel or rather substance which is in contact with it, it is said that it can
be heated without boiling to 175° C a temperature which in a Steam Boiler would
produce a pressure of about 130 lbs on the square inch-the Boiling point represents
the temperature of steam capable of exerting an expressure equal to the impressure
of the atmosphere. But the boiling point as referrod to water boiled in a common
kettle may be defined as a temperature which cannot be exceeded by any further
application of heat. Now this may vary, with Barometer, very considerably e.g at
Falmouth in December 1876 the Barometer was observed to be standing at
28-203 inches, and at Kew in the following month at 30-681 inches shewing a
range of 2.478 inches i.e over 60 mm of Mercury-and water boiled at Falmouth
on that day, at the same temperature as, on the day when the observation was
made at Kew, it would have boiled on a mountain about 2500 feet high. It boiled
at Kew at 2134° F and at Falmouth at 2084° F a difference of 41° F, now to have
made the water as hot at Falmouth as it was at Kew, no amount of firing up would
of course have been sufficient, the Definition of the Boiling point, as referred to
water boiled in a common kettle, decides this-as a common kettle would not do
it it would be necessary to devise a new kettle which, if it would do it, would
cause the definition to have to be modified by the addition of the words "without
pressure," the amount of pressure is represented by the range of the Barometer―
over 60 millimeters or nearly 2 inches of Mercury or 1lb, 21 oz, on the square
inch, and if the lid had been 3 inches diameter it would have required to weigh
9 lbs (nearly the weight of a gallon of water) to be able to keep in the steam
and in order that the water (which might not even bo boiling, as understood at
Kew, or rather under the misconception referred to) might not be violently projected
from the spout, it would be necessary that its orifice of issue should stand 33 inchos

page_text: higher than the level of the water in the kettle-such is an application of pressure
that would be necessary to make boiling water as hot on one day, as on another
day when the Barometer was higher.
Not more various is the boiling point of water than the indications which are
vulgarly relied upon as proving that the water boils.
Heat of every degree of intensity is applied to the bottom of a kettle, and the
hotter the water within the kettlo becomes, the more rapidly it is converted into
steam, the steam thus generated is expanded to about 1600 times the volume of
the water of which it is composed, it consequently rises to the surface of the water
with considerable velocity, a velocity proportional to the difference of the density
of the water and the steam, and the power of that difference to overcome the
inertia of the mass of liquid which overlies and resists the steam as it rises-and if
the water has acquired a temperature of say 200° F its power of condensing the
steam that is rising within it, back again to the condition and density of water is
limited to 12° the difference between its temperature and that of the steam-thus
if the depth of the water be shallow, as comparatively speaking, it usually is, in a
kettle, and if the intensity of the heat be great, as it may be in a Gas Stove, steam
may escape from the water, and issue from the kettle, simply because the water
had neither the time nor the power to convert it back again to water before it
escaped as the heat of the water approaches 208° or 209°, say, steam may be
observed to escape very freely, because now the condensating power of the water
is reduced to 3° or 4° say and the tension, the expressure, of the vapour is
approaching (becoming equal to) the impressure of the atmosphere, and this is
added to that of such of the air within the kettle, as has not escaped, it was itself
equal to the atmospheric pressure even before it became saturated, and it may not
have been escaping from the kettle, (while it was becoming saturated) hence, to see
the steam issuing from a kettle is not a reliable indication that it is boiling, far less
so when it is considered that steam is not visible but only vapour.
To be sure that steam is actually issuing from a kettle one must be conscious of
the escape of an invisible current at the point of issue which is resolved into a
cloud of visible vapour where cooled beyond-(a film enveloping a current of steam
may be condensed into vapour and become perceptible as it is produced and
thickens) and even then the water may not be boiling, because the steam which
was generated at the bottom of the kettle may have simply escaped from the water
before it reached the boiling point-the manner in which particles of water aro
subjected to other forces which have a superior influence upon them to that of
convection has been referred to as what takes place upon a heating surface—hence
the difficulty of knowing when a kettle boils.
This kettle is constructed to supply this much wanted indication that the boiling
point is reached, and this it doos by means of the lid, the manner of constructing
the seat of which (the hand-hole) has already been referred to-to indicate when
the water boils is a difficult problem surrounded by the most varying and delicate
considerations and it is quite hopeless to suppose that any instrument of the nature of
a simple domestic utensil will ever be produced that will indicate the exact moment
at which the water it containeds has reached the boiling point, but the indicator
provided by the lid of this kettle removes all doubt when the water is really
boiling a whistle must fail to do the same thing no matter with how much care it
may be constructed, such as that the orifice has such a diameter that the whistle is
inaudible unless the velocity of the steam passing through it is such as to indicate
that it has acquired a certain pressure, because a whistle is nothing if it is not
clean.
The lid sits loosely on its seat but so as to prevent a free escape of steam and is
so fitted in the hand-hole (which has been described) as to be free to trepidate
when a pressure of steam, due to the water's having reached the boiling point, acts
upon the underside of the lid, which is weighted so as to offer an appreciable
resistance to the expressure of the steam, then a tremulous motion of the lid will
occur producing an audible indication that the boiling point is reached-and the

page_text: water, owing to the relative height of the issue-orifice of the spout, which may be
determined, and is arranged in the manner, already referred to, may always boil
until the steam is relieved by the rise of the lid, without being projected from the
spout.
PROVISION for boiling a small quantity of water-for preventing steam bubbles
generated on the bottom of the kettle from rising in the spout, and for
indicating when the level of the water is dangerously low, if it is boiling away.
If there should be so small a quantity of water in the kettle that its level is
below the top of the adit of the spout, the lid will not indicate the boiling point, as
the vapour produced will be open to the atmosphere through the spout-again if
there should be an ordinary quantity of water in the kettle and the adit of the
spout filled with water, the hemespherical form of the kettle places the upper part
of this adit in a position to receive bubbles generated on the bottom, at the front
edge of the plate, likely to produce noisome effects, should they condense in the
spout (as well as defeating the previous supposition, the third purpose above
mentioned) these requirements are all provided for by a veil attached to the crown
of the adit of the spout having an inclination outwards, rather greater than that of
the curve of the radiating surface, at the same height above the base of the kettle,
now if this veil come down to such a level as that below which it may be
considered dangerous for the water in the kettle to be left to boil away, (care
being taken that the adit is left larger than the issue orifice of the spout) it will
serve to indicate when the water is dangerously low, by the freedom with which
the steam will be liberated through the spout.
DESCRIPTION OF DRAWINGS.
No 2 Is for the most part a side elevation, for the rest, a section, of the new
form of kettlo.
The zigzag line, from A to B represents the corrugations of the heating surface,
as they appear in the elevation, c, is the centre of this surface.
The arc A B centred at C represents the radiating surface in section.
The dotted lines borrowed from diagram N° 1 shew the determinate angle of the
lid, and its position, as regulated by a required head of water.
The arcs lettered h h and centred at C ropresent a section of the handle, and the
arrows indicate the direction of the cooling current of air which is free to pass
through the handle when it grows warm.
Of the three lines where the handle meets the spout, the curved line to the left,
represents a plate attaching the handle to the spout (this might obviously as well
be a thimble surrounding the spout), the straight line represents a boundary of the
sectional representation of the handle,-the dotted curved line is obviously that of
the spout itself.
The line V represents in section the veil projecting within the inlet of the spout.
The position of the knob, K, of the lid, as behind, and within the curves of the
shield, S, is indicated by the dotted part of the section of K.
N° 3. This figure represents the heating surface in plan-The dotted lines
represent a method of constructing a hendecagon, one side of which is achieved in
the line 3-33,-the arc which it subtends is divided by trial into three, then each
section of it represents the circular distance between the corrugations, when there
are 33, or, for any required number of corrugations, this distance may be
determined by calculation using a measure of the diameter and the ratio as
factors, in the manner set forth in the text.
The radii from 31 to 33 represent alternately ridges and furrows of straight-
corrugations, from 12 to 14 the same of curved corrugations.
N° 4. This figure represents a side elevation of the handle, giving an exaggerated
view of the form of its surface, fully and particularly described in the text.

page_text: N° 5. This figure represents an elevation of the knob and a section, or elevation,
of the lid, which the knob touches only at points-The arrows indicate the
direction of currents of cooling air entering the space under the flange, between
the points where the knob touches the surface of the lid, also passing in and out of
the knob, through spaces represented by the fluted lines.
The lines at A and B represent part of the dome in section, shewing the
recessed and receding seat of the lid, and that the lid is loose, not wedged into
.position.
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 same combined-with-a-spherical-radiating surface constructed substan-
tially as combination, substantially as described, of a corrugated heating surface
with a spherical radiating surface, for the purpose described.
+2. A Heating surface with radial corrugations, constructed substantially as
described.
3. Provision for protecting the hand from burning, through the heat of the
handle or the knob of the lid-constructed substantially as described.
4. Provision for protecting the hand from scalding by the escaping steam, con-
structed substantially as described.
5. Provision for facilitating the discharge of the water, and controlling it in
respect of quantity and direction, constructed substantially as described.
6. Provision for preventing the lid, if unattached by a hinge, from falling off,
constructed substantially as described.
7. Provision of the greatest attainable convenience for filling, constructed sub-
stantially as describod.
8. Provision of easy means of inspection, scale removal and repair, constructed
substantially as described.
9. Provision of a test for indicating that the boiling point is reached, constructed
substantially as described.
10. Provision for boiling a small quantity of water, for preventing steam bubbles
generated on the bottom of the kettle from rising in its the spout, and for indicating
when the level of the water is dangerously low, constructed substantially as
described.

page_text: I DAVID HARRY SHUTTLEWORTH BROWN of Huggin Lane Queen Victoria
Street in the City of London, Engineer, do hereby declare the nature of my
invention for AN IMPROVED CONSTRUCTION KETTLE to be as follows:-
The object of this invention is to construct a kettle with a large and efficient
heating surface, coupled with a small radiating surface, with provision for protecting
the hand froin the danger of scalding from the escaping steam, for facilitating the
discharge of the water in respect of quantity and direction and providing a test for
indicating that the boiling point is reached.
The body of the kettle 1 form of a half sphere closed at bottom by a plate having
radial corrugations by preference angular in cross section and inclining towards the
centre of the plate. The opening in the kettle for admitting liquid theroto instead
of being in the centre as heretofore and below the handle is situated in rear of the
handle and a curved shield standing up from the top of the kettle bends rearwards
over the opening for the purpose of forming a support for the rear end of the
handle and shielding the hand of the user of the kettle from the steam escaping
from under the lid it serve also to retain the loose lid in place when the kettle is
tipped for pouring.
The forward end of the handle is secured to the spout of the kettle which is
raised somewhat higher than usual. The handle is bent down in front to reach the
support and it thus facilitates the discharge of the boiling liquid both as respects
the direction and quantity of the discharge. The lid fits loosely in place but so ns
to prevent a free escape of steam. When a pressure of steam duo to the liquid
having reached the boiling point acts upon the underside of the lid a tremulous
motion of the lid will occur producing an audible indication that the boiling point
is reached.
The handle of this kettle may be made of wood or other non-conductor of heat,
the body of the kettle I prefer to make of white metal and the corrugated bottom
of sheet copper.
NEWTON & SON,
Agents for the Applicant.

page_text: I DAVID HARRY SHUTTLEWORTII-BROWN of Bello vue Villa, South Wimbledon
in the County of Surrey England, Engineer do hereby declare the nature of my
invention for AN IMPROVED CONSTRUCTION OF KETTLE" and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
The Kettles now generally in use have the smallest possible heating surface
combined with the largest practicable radiating surface, and the handles are so
constructed as to burn the hand that grasps them and are so placed that when the
water boils the steam issuing from the lid scalds the hand, which, being over the
centre of the kettle is so far from the orifice of the spout, that it has no control
over the liquid it would discharge, the quantity and direction of which, is subject
to the slightest oscillation, if the kettle is full, and is canted forward the water
escapes from under the lid and runs down the front of the kettle instead of being
poured out of the spout, if it is nearly empty the lid falls out, and may burn the
knuckles, break the china roll away and be lost and when found may be damaged―
if the kettle is not quite emptied and is taken to the tap, it is awkwardly arranged
for the admission of the tap, for which room has to be found under the hand, and
as cold water runs in, scalding vapour rushes out, and envelopes the hand, because
the lid, inlet orifice, or manhole, or rather hand hole is entirely under the hand-
and though it hardly ever happens that two persons meet who agree as to when a
kettle boils" the kettle itself is not provided, with any indicator, and either the
lid is so light and loose that it rattles as the saturated air within it is being
expanded, and escaping while the water is only warm or else it is so tightly
wedged into the hand-hole that this mere expansion of the air forces tepid water
out of the orifice of the spout which is so little above the level of the water in the
kettle that sometimes it runs out of the spout even when it is not projected by the
tension or expressure of this air in the kettle, but on account of the sheer expansion
of the water itself-and lastly the kettles now generally in use are not adapted
either to the height of the arm or to the muscles of the hand.
It
The object of this invention is to correct the defects and to supply the deficiencies
of the kettles now generally in use and to construct a kettle with the largest and
most efficient heating surface practicable combined with the smallest radiating
surface possible and with provision for protecting the hand from burning through
the heat of the handle, or of the knob of the lid as well as from the danger of
scalding by the escaping steam, for facilitating the discharge of the water and
controlling it in respect of quantity and direction, with provision for preventing
the lid, if unattached by a hinge from falling off, and for the convenience of filling
the kettle by the hand hole when it already contains some water in a state of
active vapourisation (without foregoing the easy means of inspection scale removal
and repair) with provision also for indicating that the boiling point is reached and
for avoiding any harmful projection of water from the orifice of the spout whilst
the kettle is well adapted to the height of the arm and to the muscles of the hand.

page_text: The Heating Surface is made as large as practicable by corrugating it, and is
most efficient when corrugated radially to a degree suited to the nature and
intensity of the source of heat, and when made of a metal that is a good conductor
and has a low specific Heat-As to conductivity the best known substances are
said to compare thus Copper 897, Iron 374, Porcelain 12, or thus-Silver 100,
Copper 73, Iron 11.9.
As to Specific Heat referred to Water as 1.0, Copper 0324, Silver 0571,
Iron 114 or thus, Cold hammered Copper 0934, Wrought Iron 1112, Cast
.
Irun 2411.
.
"
22
The Heating Surface may be increased by half its area when the corrugations
are such that a+b=c see Diagram No A1 in which a and bare sides of the
corrugations and c the distance between them and such a surface may be made by
hand thus, Suppose the Kettle requires to be 8" diam³ its circumference will
be 3 (8") or (8%) or th of the diameter will bend of the circumference,
take now a circle, and divide its circumference into 22 parts of 8" or 14" each—
each part will represent two sides of a corrugation a + b. Cut out one quarter of
the circle and divide each of the 22 parts into two and bend the plate radially at
the divisions till the circle has become a corrugated half circle, treat another
circlo in the same way-braze the two together and a heating surface has been
formed of two circles ie it has the area of a circle and a half, its circumference
is 27" it contains 33 corrugations, having 66 sides, which beginning at zero in the
centre become" wide at the periphery, with a circular distance of "between
them whatever the diameter of the circle, th as a divisor will give the same
angles to the corrugations, the same result could be obtained by.constructing a
hendecagon in the usual way, and bisecting its chords to obtain the 22 parts of tho
circumference-the area can be made greater or less by making the angles of the
corrugations more or less acute, and by using more or less of the circles to make
the surface, the sides of the corrugations can also be made wider or narrower i.e.
deeper or shallower by dividing the circumference into a less or greater number of
parts.
The following formule will enable any one to construct a heating surface of any
diameter, of any ratio to the area of a circle with the same diameter and with any
depth to the sides of the corrugations at the periphery and will determine the
number of sides of, and the distance between, the corrugations.
Let a = diameter, b = ratio of heating surface to area of circle with diameter a,
and let c = depth of side of corrugation, at periphery.
22 ab
Then
and
c
C
= number of sides of,
distance between the corrugations.

page_text: If the kettle is to be heated on an iron kitchen range the centre of its heating
surface may be made level with the furrows of the corrugations at the periphery,
the radial lines of these furrows will thus be in contact with the hot plate of the
range along their whole length and be acted upon by conduction there will be no
thorough draught and the sides of the corrugations will be acted upon by unimpeded
radiation, at a minimum mean distance.
If the kettle thus constructed is to be heated on a gas stove or Bunsen burner
the Aqueous Vapour which is one of the products of combustion and condenses on
the bottom of a kettle, (until it has slowly acquired such a temperature as to
become capable of absorbing such an amount of heat that condensation is no longer
possible) will, in case the coldness of the water should create excessive con-
densation, run down to the bottom edges of the corrugations, and will not have to
bo all boiled off the surface as is usual, but will be again vapourised as it hangs
down in drops from the angles of the corrugations, the sides of which it cannot
here continue to cool during its revapourisation and where the heat it is subjected
to is proportionally more intense, thus the heating surface would become dry at
an earlier period than if it were flat, and during this difference of time a heating
surface, the extent of which is represented by the ratio b is being acted upon by
the whole heat of the flame, instead of a surface represented by 1 or the ratio T
by the small amount of heat which can be transmitted through the liquid film of
condensed vapour and which, on account of revapourisation must be something
less than 212° F.
1
It is said that if air has full access to fuel all the carbon will burn to carbonic
acid CO, and all the hydrogen to water H₂O as tho oxygen of the air combines
with the carbon and free hydrogen of the fuel-and of Coal Gas, that nearly 50%
consists of hydrogen, and the rest is nearly all carbon combined in one way or
another with hydrogen-that during combustion these gases are intimately mixed
with the air in the Bunsen flame, therefore during this time their relative densities
(although they vary as 1 to 8 or even 14) can not affect their relative positions in
the flaine. Now while the aqueous vapour, produced by combustion is being
condensed on the bottom of the kettle there is an active movement among the
molecules which constitute the different resultant gases that are being produced by
a process of selection and of these, a part viz-this aqueous vapour is being
reduced in volume by as much more (or less) than 1700 times, as the difference
between the temperature of the flame and that of the condensed water is more
(or less) than the difference between 0° and 100° C-this condensation involving
an immense and instantaneous change of volume tends to produce a vacuum into
which the resultant gases tend to effuse, now the force or rate of diffusion or
effusion of different gases is said to be inversely as the square roots of their
densities, the density of CO, is said to be 1-5290, and that of aqueous vapour 6225,
(but that of the mixed gases which produce aqueous vapour is only 4147) that of
air, thus I assume that the aqueous vapour has a greater tendency to rise into
contact with or impinge against the cold surface of the bottom of the kettle than
the CO, and that if the heating surface be thus constructed viz-with its centre
lower than the ridges of the corrugations, these latter having an upward tendency,
will favour the escape, of some at least, of the aqueous vapour disengaged during
combustion which would otherwise condense (and require to be revapourised) on
the bottom of the kettle if it were domed, as it is now the practice to make what
is called a "Bachelors Kettle" to prevent "popping."
The heating surface thus constructed divides tongues of flame by wedges of
water there is perhaps no limit to the advantage of making the angles of the
wedges of water as acute as they can be made but there is a limit which cannot
well be exceeded in the corresponding angles imparted to the tongues of flame-
the depth of the corrugations gradually increases from the centre towards the
periphery, and this finds a coincidence, in the heat of the Bunsen flame which
increases from the centre towards the periphery, and this coincidence enables theso

page_text: angles to be more acute, than if it were otherwise, but they cannot be so acute
that the flame would be subdivided by cold metal to such an extent as to be
cooled till its combustion is impaired by the production of lower oxides, or
extinguished.
The advantage of a heating surface so constructed as to permit of the carly
formation and rapid rise of steam bubbles may be due to the specific heat of steam
being relatively lower than that of water (it is said to be as 4805 to 1) as well as
to the circulation or convection promoted by the rise of the steam when it is being
condensed by the water, if so the value of the low specific heat of steam is of great
importance in the furrows of the corrugations, the water is presented in detail,
and as the point of a wedge to the action of the flame on both sides of it, the edges
of the furrows become superheated points or rather lines and their power of con-
duction is (not proportionally) but in a given proportion increased the steam is
formed early here, and its low specific heat yields advantage, but the more
advantage the more rapidly it can rise, if steam is formed upon the sides of the
corrugations, it rises without impediment, if on the ridges, its rise is accelerated
by the conditions of its position-assuming that the specific heats given above
apply weight for weight, the advantages of early formation and rapid rise of steam
bubbles are obvious and important, the disadvantage arising from the lingering of
steam bubbles on the heating surface is due to the inferior power of an attenuated
vapour to absorb an amount of heat which might have been imparted by the plate
to the water, which has therefore not been transmitted, and to the diminution of
the power of the plate to receive or absorb heat as its temperature approached that
of the flame-Different explanations are given of the action of different materials
for heating surfaces, which it is said is not properly understood, smooth surfaces
are said to retard the formation and rise of steam bubbles relatively to rough ones,
and glass relatively to metal surfaces, it is also said that if a piece of inetal be
thrown into a glass vessel ebullition, which is retarded by the nature of the
material or surface of the vessel will commence, also that if pieces of glass,
granulated zinc, or tacks be thrown into a vessel, ebullition will be accelerated, the
bubbles forming on and rising from the angularities of the pieces-hence an
advantage in the corrugated heating surface the explanation of which appears to
be this.
A particle of water perhaps in contact with a point on, or above a pore in, the
plate of a flat bottoned kettle is superheated, or it contains a trace, a molecule
of air in solution and so it is selected to be converted into steam-and as rapidly
as the superincumbent pressure will permit it enlarges to 1600 or 1700 times its
own bulk-it tends to enlarge in every direction, it cannot enlarge downwards on
account of the resistance of the plate but only upwards and laterally-therefore it
tends to form a hemisphere the base of which is lying on the plate, now if this
hemisphere, this bubble of steam could be imagined to have a corrugated bottom as
this kettle has, it would probably rise iminediately but it has not, and it has taken
this form on account of the equal resistance which it met (during its formation) in
the vertical and statical pressure of the superincumbent liquid, at any point of time
while the bubble was expanding and before it had attained its maximum dimensions,
it was under pressure inversely proportional to its volume and its heat was pro-
portional to the pressure (the pressure measurable by the momentum imparted to
the particles of superincumbent water) the particles of the water which resist the
pressure of the nascent bubble are affected by its hent first on that side on which
they receive it (now it is said that pure water in a state of ebullition is a
phenomenon which has yet to be witnessed) these particles may contain air in
solution which being suddenly expanded tends to rise and causes the particles to
revolve in a direction which for each particle is in a radial line from the centre of
the bubble the source of heat-a film separated from the mass of quiescent liquid
by its particles having this motion imparted to them lies upon the inclined surface
of the hemisphere and its particles convey the impulse they have received, with
diminishing energy to the particles adjoining them in the mass of liquid and the

page_text: direction of their momentum prevents them from passing under the bottom of the
bubble or hemisphere, the centre of which is in an opposite direction to that of this
acquired momentum-the superincumbent liquid has by its statical pressure to
break through the film (the energy of which approached from without, would be
found to increase in intensity) before it can pass under- the bubble, but if the
bottom of the vessel is as smooth as glass there are no breaks in its continuity the
lateral radial force of the expanding bubble has pushed all the liquid before it,
there is no liquid under the bubble there is no inlet, the activated film of revolving
particles remains unbroken the statical pressure of the liquid has been defeated
and the bubble adheres to the bottom-If this is accepted it is unnecessary to
explain how steam bubbles formed on the sides of the corrugations rise without
impediment, and how if formed on the ridges, their rise is accelerated by the
conditions of their position-if formed in the furrows ?-the top of the ridge is a
line which has a sensible width, the base of the furrow is a geometrical line.
The acquirement and retention by a particle of water of 5-36 times the amount
of heat which the body of the liquid, in which it exists, has acquired or can retain,
must be due to its being cut off by such a revolutionary motion as that ascribed to
the particles constituting the film encompassing the steam bubble, the gases of the
air which it holds in solution are differentially soluble at the temperature which it
has acquired, these gases may be intimately mixed, but ultimately their nolecules
must bo side by side and thus when one expands more than the other the particlo
is thrown out of equilibrium and is caused to revolve by the energy which the
molecule of gas exerts in passing from the liquid or dissolved condition into the
gaseous, it revolves on the point, (not to say the molecular pole, or the geometrical
point, but) the microscopical point on the heating surface which imparted the heat
which disturbed its equilibrium and continues to receive and absorb the heat of
which the particles that surround it can receive only some, as they too are caused
by it to revolve, but with rapidly diminishing force on account of the proximity of
those on opposite sides of the particle which revolve in opposite directions to cach
other and also of the friction produced by (and therefore tendency to reverse the
motion of) particles on any, the same, side of it revolving each in the same
direction (the cause of diminution of revolving force transmitted by the particles of
the film above referred to) it is therefore, being thus surrounded, and, unaffected
by convection, entirely subject to the influence of its revolution on the point from
which it acquires its heat until it has acquired so much that (? burst by centrifugal
force) it is converted into steam-the influence of the nature or material of the
beating surface upon ebullition is here presumptively accounted for..
Now as to incrustation or the deposit of scale-it is said that "the tendency to
forin scale is the greater, the slower the deposit is laid down-that a portion of
the earthy carbonates is deposited as soon as the water is warmed, another only
after considerable boiling, while some remains in solution even in boiling water'
thereforo the more effective the heating surface, i.e, the quicker the water is boiled
the less the deposit and the greater the area of the deposit the thinner the scale-
the scale deposited on an inclined surface is not so hard as that on a flat surface.
The Radiating Surface is made in the form of half a sphere, which presents,
with other advantages the smallest possible radiating surface (the sphere among
geometrical figures being that which relatively to its contents has the least
possible superfices) it should be made of a metal that has little power of conduction
if possible combined with little power of radiation.
To diminish radiation the surface is burnished, if it were coated for this purpose,
with a metal of greater density their coefficients of expansion should be as nearly
equul as possible. The heat which this form of radiating surface derives from the
bottom of the kettle or the source of heat can only on account of the shape bo
applied to the water from above in a direction downward varying with the radius
which soon becomes a direction in which the water is almost incapable of receiving
heat such heat must therefore be lost by radiation and absorbed by the mountings
of-the kettle hence the necessity of the radiating surface being made of a metal

page_text: which is a bad conductor, this however is limited by the consideration that it is
said that if the distance from the source increases in arithmetical progression the
conducted heat decreases in geometrical progression-if this part of the kettle be
made of copper-advantage may be taken of the effect which it is said small
quantities of impurities in the metal have upon its conductivity-as the heat of
the water the conducting power of which is exerted by convection upwards is lost
to some determinable extent by conduction through the radiating surface.
An advantage (a counterpoise to this last named loss) arises out of this shape of
the body of the kettle from what is said of the effect of limiting or extending the
evaporating surface of water-Evaporation from the surface of a liquid deprives
the liquid of hent (produces cold) and evaporation is proportional to the surface
exposed and therefore the more limited the surface the greater the accretion of heat
in the liquid the shape of the kettle is such that the more liquid it contains the
more limited is the evaporating surface, this is thought also to raise the boiling
point which if it can be done by economising the heat is a decided advantage.
The relative radiating powers of the best known metals are said to be in the
following proportions to that of Lamp black as 100 viz polished iron 15 Tin Gold
Silver Copper 12 they are also said to be in the following proportions Silver 5.36
Copper foil 4.90 and Silver burnished 2.50.
PROVISION for protecting the hand from burning through the heat of the handle
or of the knob of the lid.
The handle is bent down in front of the kettle and its position is that of an arc,
in a verticle plane, concentric with the body of the kettle, the fore part of the
handle being attached to the spout and the hind part to a hood guard plate shield
or baffle plate which is rounded in front and partly surrounds the lid behind it and
rises in such a curve as allows room below and behind for the handle or knob of
the lid and room above and in front for the fingers between it and the handle of the
kettle.
The handle is made non-conducting substances which are non conductors not
being so permanent as the metals it is made of a metal which has small conductivity
(such as pure aluminium would have, when cast) it is a hollow tube the ends of
which are not closed so that the air may circulate through it in an upward current
from the front towards the back of the kettle-and to increase its radiating surface
it is acutely corrugated longitudinally and the ridges of the corrugations are cut
across (or embossed) or vice versa so as to leave only points to come into contact
with the skin of the hand the whole.having a dull or frosted finish.
The knob of the lid is hollow, and perforated or divided into sections which the
air can traverse, between the corrugations, which whether longitudinal or transverse
have the same surface as those of the handle,-between the bulbous part of the
knob, if it have a bulb, or the top of it and the lid the shank is sufficiently long to
admit the fingers between the bulb or top and a large flange which touches the lid
only at points (three are preferable) to protect the fingers or knuckles from the
heat of the lid.
PROVISION for protecting the hand from Scalding by the escaping Steam.
For reasons to be stated it may be taken for granted that water in an ordinary
kettle on an ordinarily fun in and

page_text: PROVISION of easy means of inspection scale removal and repair, by a hand-hole so
arranged as to present other advantages.
The hand-hole is large enough for the admission of light, a hand, or a brazier's
tools, and the edge within the kettle is not tapered inwards, as is usual, but is
recessed outwards, so that, it does not wedge the lid, and so that the hand-hole can
be easily withdrawn the body of the kettle being spherical, a segment of the sphero
proportional to the diameter of, and above the plane of the hand-hole is cut off-
the angle at which it is placed with regard to the base of the kettle has been
defined the effect of this angle is to bring the centre of the handbole behind the
apex of the hemisphere, so that it is not over the centre of the base and the back
part of it is at a lower level than the front.
It sometimes happens that a kettle is filled too full and then the water becoming
warm expands and runs over out of the spout, when it is said to be boiling over
(and it may afterwards really be doing so) and if the air, above it has been unable
to escape, it also expands and its expressure forces still more water out of the spout
than would merely run over. Now in this kettle such water would run out from
under the lid, but at the back, and if it were really in a condition to be boiling
over, the water would merely trickle down the back of the kettle and damp the
fire instead of doing any injury that might arise from water, or boiling water
being forced out of the spout. Water expands in volume 4% between the ordinary
temperature of the atmosphere and the boiling point.
PROVISION of a Test for indicating that the Boiling point is reached.
The Boiling point is so often defined as 212° F that a misconception of what the
boiling point really is, requires to be removed before it is possible to indicate that
it is reached, the definitions of it are a little various, and though it has been made.
available as a fixed point it is as variable as the weather and changes with the
Barometer to begin with, it does not refer to water, which can be made to boil at
almost any temperature at which it does not freeze, whilst according to the nature
of the vessel or rather substance which is in contact with it, it is said that it can
be heated without boiling to 175° C a temperature which in a Steam Boiler would
produce a pressure of about 130 lbs on the square inch-the Boiling point represents
the temperature of steam capable of exerting an expressure equal to the impressure
of the atmosphere. But the boiling point as referred to water boiled in a common
kettle may be defined as a temperature which cannot be exceeded by any further
application of heat. Now this may vary, with Barometer, very considerably e.g at
Falmouth in December 1876 the Barometer was observed to be standing at
28-203 inches, and at Kew in the following mouth at 30-681 inches shewing a
range of 2.478 inches i.e over 60 min of Mercury-and water boiled at Falmouth
on that day, at the same temperature as, on the day when the observation was
made at Kew, it would have boiled on a mountain about 2500 feet high. It boiled
at Kew at 213° F and at Falmouth at 2083° F a difference of 44° F, now to have
made the water as hot at Falmouth as it was at Kew, no amount of firing up would
of course have been sufficient,-the Definition of the Boiling point, as referred to
water boiled in a common kettle, decides this-as a common kettle would not do
it it would be necessary to devise a new kettle which, if it would do it, would
cause the definition to have to be modified by the addition of the words "without
pressure" the amount of pressure is represented by the range of the Barometer-
over 60 millimeters or nearly 24 inches of Mercury or 1 lb, 2 oz on the square
inch, and if the lid had been 3+ inches diameter it would have required to weigh
9 lbs (nearly the weight of a gallon of water) to be able to keep in the steam―
and in order that the water (which might not even be boiling, as understood at
Kew, or rather under the misconception referred to) might not be violently projected
from the spout it would be necessary that its orifice of issue should stand 33 inches

page_text: higher than the level of the water in the kettle-such is an application of pressure
that would be necessary to make boiling water as hot on one day, as on another
day when the Barometer was higher.
Not more various is the boiling point of water than the indications which are
vulgarly relied upon as proving that the water boils.
Heat of every degree of intensity is applied to the bottom of a kettle, and the
hotter the water within the kettle becomes, the more rapidly it is converted into
steam, the steam thus generated is expanded to about 1600 times the volume of
the water of which it is composed it consequently rises to tho surface of the water
with considerable velocity, a velocity proportional to the difference of the density
of the water and the steam, and the power of that difference to overcome the
inertia of the mass of liquid which overlies and resists the steam as it rises-and if
the water has acquired a temperature of say 200° F its power of condensing the
steam that is rising within it, back again to the condition and density of water is
limited to 12° the difference between its temperature and that of the steam-thus
if the depth of the water be shallow, as comparatively speaking, it usually is, in a
kettle, and if the intensity of the heat be great, as it may be in a Gas Stove, steam
may escape from the water, and issue from the kettle simply, because the water
had neither the time nor the power to convert it back again to water. before it
escaped as the heat of the water approaches 208° or 209°, say, steam may be
observed to escapo very freely, because now the condensating power of the water
is reduced to 3° or 4° say and the tension, the expressure, of the vapour is
approaching (becoming equal to) the impressure of the atmosphere, and this is
added to that of such of the air within the kettle, as has not escaped, it was itself
equal to the atmospheric pressure even before it became saturated, and it may not
have been escaping from the kettle, while it was becoming saturated hence to sce
the steam issuing from a kettle is not a reliable indication, that it is boiling, far less
so when it is considered that steam is not visible but only vapour.
To be sure that steam is actually issuing from a kettle one must be conscious of
the escape of an invisible current at the point of issue which is resolved into a
cloud of visiblo vapour where cooled beyond (a film enveloping a current of steam
may be condensed into vapour and become perceptible as it is produced and
thickens) and even then the water may not be boiling because the steam which
was generated at the bottom of the kettle may have simply escaped from the water
before it reached the boiling point-the manner in which particles of water are
subjected to other forces which have a superior influence upon them to that of
convection has been referred to as what takes place upon a heating surface hence
the difficulty of knowing when a kettle, boils.
This kettle is constructed to supply this much wanted indication that the boiling
point is reached and this it does by means of the lid the manner of constructing
the seat of which (the hand-hole) has already been referred to-to indicate when
the water boils is a difficult problem surrounded by the most varying and delicate
considerations and it is quite hopeless to suppose that any instrument of the nature of
a simple domestic utensil will ever be produced that will indicate the exact moment
at which the water it contained has reached the boiling point, but the indicator
provided by the lid of this kettle removes all doubt when the water is really
boiling a whistle must fail to do the same thing no matter with how much care it
may be constructed such as that the orifice has such a diameter that the whistle is
inaudible unless the velocity of the steam passing through it is such as to indicate
that it has acquired a certain pressure, because a whistle is nothing if it is not
clean.
The lid sits loosely on its seat but so as to prevent a free escape of steam and is
so fitted in the hand-holo (which has been described) as to be free to trepidato
when a pressure of steam due to the waters' having reached the boiling point acts
upon the underside of the lid which is weighted so as to offer an appreciable
reisistance to the expressure of the steam, then a tremulous motion of the lid will
occur producing an audible indication that the boiling point is reached and the

page_text: water owing to the relative height of the issue-orifice of the spout, which may be
determined, and is arranged in the manner, already referred to may always boil
until the steam is relieved by the rise of the lid without being projected from the
spout.
PROVISION for boiling a small quantity of water-for preventing steam bubbles
generated on the bottom of the kettle from rising in the spout, and for
indicating when the level of the water is dangerously low if it is boiling away.
If there should be so small a quantity of water in the kettle that its level is
below the top of the adit of the spout, the lid will not indicate the boiling point as
the vapour produced will be open to the atmosphere through the spout-again if
there should be an ordinary quantity of water in the kettle and the adit of the
spout filled with water the hemespherical form of the kettle places the upper part
of this adit in a position to receive bubbles generated on the bottom, at the front
edge of the plate, likely to produce noisome effects should they condense in the
spout (as well as defeating the previous supposition the third purpose above
mentioned) these requirements are all provided for by a veil attached to the crown
of the adit of the spout having an inclination outwards rather greater than that of
the curve of the radiating surface, at the same height above the base of the kettle,
now if this veil come down to such a level as that below which it may be
considered dangerous for the water in the kettle to be left to boil away, (care
being taken that the adit is left larger than the issue orifice of the spout)—it will
serve to indicate when the water is dangerously low by the freedom with which
the steam will be liberated through the spout.
DESCRIPTION OF DRAWINGS.
No 2 Is for the most part a side elevation, for the rest, a section, of the new
form of kettle.
The zigzag line, from A to B represents the corrugations of the heating surface,
as they appear in the elevation,-C, is the centre of this surface.
The arc A B centred at C represents the radiating surface in section.
The dotted lines borrowed from diagram No 1 shew the determinate angle of tho
lid, and its position, as regulated by a required head of water.
The arcs lettered h h and centred at C represent a section of the handle, and the
arrows indicate the direction of the cooling current of air which is free to pass
through the handle when it grows warm.
Of the three lines where the handle meets the spout, the curved line to the left,
represents a plate attaching the handle to the spout (this might obviously as well
be a thimble surrounding the spout), tho straight line represents a boundary of the
sectional representation of the handle,-the dotted curved line is obviously that of
the spout itself.
The line V represents in section the veil projecting within the inlet of the spout.
The position of the knob, K, of the lid, as behind, and within the curves of the
shield, S, is indicated by the dotted part of the section of K.
No 3. This figure represents the heating surface in plan-The dotted lines
represent a method of constructing a hendecagon, one side of which is achieved in
the line 3-33, the arc which it subtends is divided by trial into three, then each
section of it represents the circular distance between the corrugations, when there
are 33, or, for any required number of corrugations, this distance may be
determined by calculation using a measure of the diameter and the ratio
factors, in the manner set forth in the text.
as
The radii from 31 to 33 represent alternately ridges and furrows of straight
corrugations, from 12 to 14 the same of curved corrugations.
No 4. This figure represents a side elevation of the handle, giving an exaggerated
viow of the form of its surface, fully and particularly described in the text.

page_text: No 5. This figure represents an elevation of the knob and a section, or elevation,
of the lid, which the knob touches only at points-The arrows indicate the
direction of currents of cooling air entering the space under the flange, between
the points where the knob touches the surface of the lid, also passing in and out of
the knob, through spaces represented by the fluted lines.
The lines at A and B represent part of the dome in section, shewing the
recessed and receding seat of the lid, and that the lid is loose, not wedged into
position.
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
1 claim is
1. A Heating surface with radial corrugations constructed substantially as
described.
2. The same combined with a spherical radiating surface constructed substan-
tially as described.
3. Provision for protecting the hand from burning through the heat of the
handle or the knob of the lid-constructed substantially as described..
4. Provision for protecting the hand from scalding by the escaping steam con-
structed substantially as described.
5. Provision for facilitating the discharge of the water and controlling it in
respect of quantity and direction constructed substantially as described.
6. Provision for preventing the lid if unattached by a hinge from falling off,
constructed substantially as described.
7. Provision of the greatest attainable convenience for filling constructed sub-
stantially as described.
8. Provision of easy means of inspection, scale removal and repair constructed
substantially as described.
9. Provision of a test for indicating that the boiling point is reached constructed
substantially as described.
10. Provision for boiling a small quantity of water, for proventing steam bubbles
generated on the bottom of the kettle from rising in its spout and for indicating
when the level of the water is dangerously low, constructed substantially as
described.
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