An Improved Differential Temperature Air Motor, adapted for Soientific Applications, for Philosophical Toys, and for Advertising and other Purposes.
Year: 1896

page_text: Date of Application, 25th Apr., 1898
Complete Specification Left, 25th Jan., 1897-Accepted, 24th Apr., 1897
PROVISIONAL SPECIFICATION.
An Improved Differential Temperature Air Motor, adapted for
Soientific Applications, for Philosophical Toys, and for
Advertising and other Purposes.
ALFRED ROSLING BENNETT 22, St. Alban's Road, Harlesden, London, N.W.,
in the County of Middlesex, Engineer, do hereby declare the nature of this invention
to be as follows:-
This invention is founded on the fact that some substances are more dia-
thermanoue, or permeable to heat, for rays which proceed from a highly heated
source, such as the sun or an incandescent body, than for rays emanating from
bodies at a comparatively low temperature, such as warmed metal or wood.
An ordinary cucumber frame or a glass-covered conservatory or greenhouse may
be adduced as an illustration of the phenomenon upon which my invention depends.
In the case of such a structure the sun's rays penetrate freely through the glass
without appreciably heating it and raise the temperature of the interior and of the
contained objects to many degrees above that of the outside air. The contents of
the glass-covered structure do not fall to the temperature of the outside air for a
considerable time after sunset because they cannot radiate their heat freely back
through the glass but have to lose it slowly by conduction through the framework
and by connection, air currents being formed within which gradually convey the
heat of the contained objects to the glass by which it is absorbed and radiated to
the cooler outside air. Bodies, together with the air contained, in such a structure
are consequently quickly heated by exposure to a source of high temperature
while they can cool but slowly, and upon this fact one part of my invention
depends.
A second part of my invention rests upon the power of such a glass-covered
framework to lose or radiate heat in the absence of the sun or other exterior
source of high temperature. If an object under a glass shade which is not exposed
to an exterior source of heat be continuously supplied with heat by conduction, for
instance through a metal bar, or by heated air or water conveyed to it by piping,
the air within the shade will be heated by contact with the object, air currents will
be set up and maintained so long as the supply of heat lasts, and a continuous.
transfor of heat by connection from the object to the glass and thence to the outer
air will occur.
The second part of my invention therefore deponds upon creating and main-
taining independently of sunshino or daylight a difference of temperature
between a motor within a shade or box and the exterior of the said shade or
box which should wholly or in part be made of a substance which radiates beat
freely.
Effect to the first part of my invention may be given by placing under an
ordinary glass clock shade a delicately-poised radiometer vane enclosed in a
mica screen having a longitudinal opening in one of its sides as described in my
British Specification No. 10,769 of 1890, or any other suitable motor capable of
being actuated by minute currents of air. On such an arrangement being exposed
to sunshine or to direct daylight, either by placing it in the open air or near a
window, the motor will become heated by direct radiation through the glass shade
from the outside and acquire a different temperature from that of the exterior

page_text: surface of the glass shade itself. Warmed air will ascend through the interior of
the motor screen, emerge from its top, become cooled by contact with the glass
shade, descend and be drawn again into the bottom or side inlet of the notor
A continuous circulation of air through the motor will consequently take
place which will set in motion the vane or other moving part.
After sunset or the withdrawal of the exterior sourco of heat the motor will
continue to work until its surfaces and the air within the shade have acquired the
temperature of the exterior of the glass shade or so nearly so that the remaining
differences in temperature are insufficient to maintain in circulation an air current
of the requisite strength to work the motor.
By placing the interior of the glass shade and of the motor screen by means
of suitable openings, channels or pipes in communication with the interior of a
cucumber frame or greenhouse so that the heated air of the frame will ascend into
the interior of the motor and be replaced by the air which has been cooled by
contact with the glass shade, the mechanism will be operated a long time after the
external source of heat bas been withdrawn as it will be necessary for the whole of
the air in the frame as well as that in the shado to become cooled before the motion
will cease. Instead of using a cucumber frame or greenhouse for a reserve store
of heat the glass shade and its contained motor may be made to communicate with
a wooden or metal vessel, preferably air-tight, in such a way that the motor can
draw air only from the said vessel while the cooled air after contact with the glass
shade has no exit except by descending into the vessel. In this case, while the
external source of heat endures the whole of the air in the shade and in the closed
vessel is passed again and again through the motor and is heated there to a degree
above that of the temperature of the external air. Even after being cooled by
contact with the glass it will be warmor than the exterior of the glass shade so
that the closed vessel will gradually be filled with air warner than the outside
atmosphere. After the external source of heat has been withdrawn the air will
continue to circulate through and work the motor until the whole has been reduced
to the temperature of the exterior of the glass shade or nearly so. The closed
vessel should preferably be covered with non-conducting compound or embedded in
dry straw or other bad conductor of heat, so that its internal heat may not be lost
by radiation.
After motion has ceased in apparatus such as is hereinhefore described.it may
be renewed by placing damp cloths or ice on the glass shade or by allowing water
to flow over it.
The glass shade may be fitted air-tight to its stand but the motor will never-
theless operate if it is made open at the top and provided with openings at the base,
but with such a mode of construction the amount of reserve heat that can be
stored is reduced while the motor is apt to be disturbed by outside currents
of air.
lustead of causing the same air to circulate again and again through the motor,
the motor may be arranged to draw air from the outside and the glass shade to
exhaust the air after cooling into the external atmosphere.
The apparatus hereinbefore described will not operate in the interior of a room
if withdrawn from the sunshine or other source of 'bigh temperature since in that
case both the motor and its shade acquire the temperature of surrounding objects
and there being no difference of temperature between the motor and its shado there
can be no motion.
According to the secoud part of my invention, while the apparatus auch has been
bereinbefore described is retained, artificial heat is supplied to the motor either for
the purpose of causing it to work in a closed room or to reinforce or supplement
the sunshine or daylight heat or to continue its operation during the night. This
may be accomplished in several ways. An incandescent electric lamp or other
electric heating apparatus may be fixed so as to heat the air in the motor, cause it
to ascend, become cooled by contact with the glass shade and finally to descend and
re-enter the motor or be exhausted to the external atmosphere. Or the base of the

page_text: motor may be fixed to one end of a metal bar or rod the other end of which is heated
by a fire or otherwise, at a distance from the apparatus. If a metal rod, preferably
of copper, be sunk in the earth to a depth at which the temperature is permanently
above that of the atmosphere and precautions are taken to prevent loss by radiation
when passing through the cooler parts nearer the surface a constant supply of heat
will be afforded which will be constantly radiated by the glass shade and the motor
will never stop. Or an air chamber or coiled pipe buried in the earth at such a
depth of constant temperature may communicate with the motor and with the shade
by means of pipes suitably protected from radiation so that a continual stream of
warmed air will ascend to the motor and of cooled air descend from the shade.
Such an arrangement would be particularly applicable when a body of water is
available since water cools much more gradually than does the surface of the earth
so that the temperature of the bottom water in deep ponds and reservoirs is at night
usually above that of the air near the ground. By means of a sunken air chamber
or coiled pipe and suitable connecting pipes a motor could be supplied with air at a
temperature above that of the exterior surface of its shade and kept in motion all
night, the heat derived from the water being radiated by the shade. Waste heat
from furnaces, boilers, vats, ovens, chimneys and other sources could similarly be
conveyed by air or water pipes, or by conduction through metal, to the motor. The
energy of the resulting motion may be increased by improving the radiating power
of the shade by causing cold water to flow over it, by packing it in ice, by wrapping
it in wet cloths, or by placing upon its outer surface porous material kept
constantly wetted with water, sulphuric ether or other liquid capable of causing
rapid evaporation.
The uses of such an apparatus as is herein before described are manifold. When
the motor consists of a vane rotating within a mica screen as described in the
beforementioned Specification No. 10769 of 1890, its sensitiveness to small
differences of temperature is exceedingly great, while the speed of rotation is
constant for any given temperatures of motor and shade. For instance, if the
shade be packed in ice while the motor by means of hot air or steam is kept at the
temperature of boiling water the number of revolutions per minute, which may be
registered ou dial connected with the spindle, of the motor or by causing the
spindle to make and break electrical contacts, will always be the same for the same
instrument. The apparatus may therefore be used in thermometry and calorimetry
and for scientific experiments and investigations. By connecting the interior of the
motor to a cuiled pipe or other similar device the other end of which is in con-
munication with the space just inside the shade the motor may be started by
holding the coiled pipe in the hand or by immersing it in warm liquid, air or gas.
The heat set free by the mixture of chemicals, as sulphuric acid and water, may be
thus used to operate the motor. By causing the coiled pipe to form part of an
electrical conductor or by placing it so that it may receive heat from a neighbour-
ing electrical conductor the instrument may be adapted to act as a meter of
electricity.
The apparatus by means of electrical contacts may be used to give notice at a
distance of an increase or a variation in temperature. It may likewise be utilised
as a sunshine recorder, as an instructive philosophical toy, and by painting words
or designs on the vanes of the motor or on objects driven by the motor, as au
advertising device.
When the motor is provided with a large fan, spindle and pulley, and supplied
with artificial heat, particularly when the shade is simultaneously cooled by water,
evaporation, ice or otherwise, the motor is capable of developing useful power an'l
may be applied generally to the purposes of small motors. The spindles of several
or many instruments may be coupled by chains and spockets, cords and pullies or
by friction rollers so as to collectively furnish a considerable power.
Dated shi Twanto fourth day of April 1806

page_text: An Improved Differential Temperature Air Motor, adapted for
Soientific Applications, for Philosophical Toys, and for
Advertising and other Purposes.
I, ALFRED ROSLING BENNETT, of 44 Manor Park Road, Harlesden, late of
22 St. Alban's Road, Harlesden, in the County of Middlesex, England, Electrical
Engineer, do hereby declare the nature of this inveution and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention relates to motors that have for their source of power the radiant
heat of the sun or of an artificial source of heat, the action being if desired
supplemented by heat conveyed to the motive fluid by conduction. In some
instances the action of the motor is assisted by heat automatically stored in suitable
reservoirs.
The said motor comprises essentially a tube or chimney, a fan or vane arranged
to turn oD a pivot in said chimney, and a glass or other shade enclosing the
chimney.
The construction and mode of operation of the said motor or self-acting heat
engine will be described with reference to the accompanying drawings, in which
Figure is a vertical contral section of a simple form of the motor, and
I
Figure 2 is a sectional plan thereof.
Figure 3 is a vertical section of a similar motor in combination with a liquid
cell for storing heat.
Figure 4 is a sectional elevation of a modified form of the motor with the
addition of an air reservoir for, storing heat.
Figures 5, 6 and 7 are horizontal sections on the lines,,, y, and z 3
respectively of Figure 4, and
Figure 8 is a vertical section of a modification of the motor shown in
Figure 4.
Figures 9 to 13 are vertical ceutral sections ou a smaller scale of various
modifications of the motor.
Figure 14 is a similar section, and
Figure 15 is a plan illustrating a method of using the device for calorimetry and
similar purposes, aud
Figure 16 is a vertical central section of a further modified form of the
device.
Like letters denote corresponding parts in the several figures.
A, Figures 1 and 2 is the tube or chimney open at top and bottom. The lower
part of the said tube is preferably made of transparent material, mica or glass
for example in order that the fau hereinafter described may be seen; the upper
part of the tube is preferably made of metal. It is supported on a staud B
furnished with legs B¹ and having a central aperture through which the air can
gain access to the tube or chimney as indicated by the arrows. Within the
chimney and supported on a thin metal bridge C is mounted a finely pointed steel
needle which carries by means of an agate cup an accurately-balanced fan E of
aluminium or other suitable material. The blades of the fan are inclined at
any desired augle to the plane of the arms. F is a bent metallic arm attached
to the chimney and adapted to prevent the fan from falling off its pivot during
transport. The whole is enclosed by a shade or cover G preferably of glass or
mica or other good absorber and radiator of heat, which shade rests upon a table
or support.

page_text: On placing such an apparatus in the open air or in a room near a window, which
should preferably be open, the direct rays of the sun if it is shining, or otherwise
the diffused radiant heat of daylight, will pass through the shade and warm the
fan, its supports, and the walls of the chimney, whereupon the air in contact with
these surfaces will become warmed and rarefied and will ascend and issue from the
top of the chimney as indicated by the arrows.
On making contact with tho shade or cover G the excess of heat in the air will
to a large extent be absorbed by the shade and be radiated by the lattor outwardly.
The air within the shade being thus cooled descends to the bottom of the shade
whence it is drawn into the chimney and again heated by contact with the
chimney and with the fan, and the cycle of operations is repeated. The circulation
of air thus set up is continuous by night as well as by day so long as the
temperature of the inotor surfaces, that is to say, the temperature of the tube and
fan slightly exceeds that of the skiu of the shade. The current of air operates to
turn the fun which can be seen revolving through the glass shade.
The fan when well made and well balanced will usually rotato all day in the
open air whatever the weather conditions may be and all night also if the sky be
clear, the barometrical pressure high, and the weather fine and calm. The
direction of rotation may in certain weather conditions become reversed. Other
arrangements of fans or vanes may be devised without departing from the spirit of
my invention which comprises a fan mounted in a tube or chimney in combination
with a shade or cover used as a radiator but is not confined to any particular
construction of the fan.
The above described motor will not usally continue in action during the night
if the sky is cloudy, the barometrical pressure low, or the weather inclement.
To promote an all-night action in such weather I modify the apparatus by adding
a reservoir in which heat may be automatically stored during daylight and given
out during the night. Of such storage arrangements' I have illustrated two by way
of example.
The first is shown in Figure 3 wherein the chimney above described with its fan
is mounted on the upper end of an annular vessel which is arranged with its axis
vertical and which is nearly filled with water or other liquid. The outer wall of
the said vessel should be covered with felt h or other bad conductor of heat. H' is
a conical nozzle around the upper end of the cavity of the vessel and extending
into the lower end of the chimney and so formed as to leave an annular air-
space J between it and the inner side of the chimney. During daylight, air is
drawn into the motor at two places indicated by the arrows, namely from the
bottom through the internal cavity of the annular vessel and through the air-
space J. The liquid stores up lieat gradually during daylight and when the
outside temperature has fallen it gives out the heat slowly to the air within the
cavity of the vessel thus warming the air and causing it to ascend through
the nozzle H' into the chimney and thereby to impart rotation to the fan. Enough
heat is usually stored in the liquid to keep the motor working all night whatever
the weather conditions may be. The air space J is provided in order that when
daylight returns and the motor begins to work by direct radiant heat instead of by
stored heat air may be drawn into the chimney more directly than through the
long inner tube of the vessel.
The annular vessel may be arranged to contain small fragments of material or
powder, in lieu of liquid.
Another and more efficient method of storing heat for use at night is that showa
in Figures 4 to 7 in which K is an air-tight chamber having double walls, the
space between the walls being packed with dry saw-dust or other bad conductor
of heat.
In some instances the outer wall may be dispensed with provided the vessel be
covered thickly and efficiently with asbestos cloth or other bad conductor of heat.
The motor is fitted on the top of this chamber. Projecting into the lower part of
the chimney of the motor is a nozzle II' which forms the termination of a tube H

page_text: extending from a box L. The said box is closed at the bottom and is furnished
with branching tubes L' communicating with the interior of the chamber K. The
said tubes project through and are supported by a funnel M which is secured at
its upper end to the rim around the mouth of the chamber. The lower end of the
funnel terminates in an open pipe M' that extends nearly to the bottom of the
chamber K. An annular opening is provided as before between the nozzle H
and the chimney of the motor. If the funnel M be made of metal it should
preferably be covered with felt or asbestos cloth, and the tubes L', the box L. and
the tube H should be similarly protected. If the walls of the chamber K be
made of metal, non-conducting material should be interposed between them and
also between the said walls and the supports of the motor, as it is desirable to keep
the storage portions of the apparatus thermally insulated from the other parts to
prevent loss of heat by couduction. Vessels containing liquid as indicated at N, N
or bricks or tilos may be used for increasing the heat storage capacity.
The action is as follows. During daylight the surfaces of the fan and of the
chimney become heated by radiant hent, and the air in contact with them is
rarefied and caused to ascend and to issue from the upper end of the chimney
whereupon it parts with some of its heat to the shade or cover and descends by
the walls of the shade and passes down the pipe M' to nearly the bottom of the
reservoir. Thence it ascends to take the place of other air drawn into the chimney
and passes through the tubes L', the box L, the tube H and the nozzle H' and is
ultimately drawn into the chimney again. By contact with the shade the air
becomes cooled below the temperature which it possessed when in the chimney but
some of its excess heat is retained and carried downward into the chamber K and
is there imparted to the walle of the said chamber to the non-conductor behind
the walls and to the vessels of liquid or other heat reservoirs N if any in the
chamber, the temperature of which parts is caused to approximate to that of the
outside in the daytime. Since the reservoir is sheathed in non-conducting
material, the stored heat cannot be readily lost by radiation and it is therefore
retained until, on the approach of night, the outside temperaturo falls below that
of the reservoir and the fan and chimney cease to receive enough heat from outside
to maintain the motion. Then the stored heat is given out by the reservoir and
the comparatively warm air rises through the nozzle H¹ and passes through the
motor and chimney, giving motion to the fan, and ultimately yielding its heat to
the glass and falling back cooled into the reservoir, where it receives fresh heat
from the walls, vessels of liquid or other heat reservoirs and once more rises. By
this method it is found that enough heat can be stored to maintain the circulation
until the return of daylight when the fan and chimney resume their functions as
heating surlaces and heat is once more stored in the reservoir. An alternative
channel J for the entrance of air surrounds the nozzle H'. Were there no such
opening, the heating surface represented by the motor and its chimney would have
to keep in motion an inert column of air equal in length to that of the pipe M
and its sensitiveness would be much reduced; with the said opening a portion of
the air during daylight is drawn direct from the shade. It is nevertheless found
that sufficient air for heat storing purposes makes the circuit of the reservoir. The
course of the air circulation is denoted by the arrows. In this modification the
chimney is shown split up into several smaller tubes to increase the heating
surface.
In the foregoing instrument the rotation of the fan is always in the same
direction. In the modification shown in Figure 8 the fan rotates in one direction
during the day and in the reverse direction during the night. In this instance
the motor is fixed directly on the pipe M' without any alternative air openings.
During daylight the fan and chimney, acting as heating surfaces, keep the air in
motion as indicated by the arrows and cause heat to be stored in the reservoir.
At the approach of night the heating surfaces cease to act and the fan stops for a
time, but owing to the fact that more heat has been stored in the walls of the

page_text: chamber K than in the pipo M', warmed air begins to rise from the chamber into
the shade in the reverse direction to that indicated by the arrows. Such air
becomes cooled in the sbada and by reason of more warm air rising from the
chamber K the cooled air is forced into the chimney whence it descends through
the pipe M and rotates the fan in its passage. On daylight appearing the heating
surfaces again act, the motion is once inore in the direction of the arrows and heat
is stored in the chamber K.
The apparatus herein before described will not operato in the interior of a roon.
when withdrawn from the sunshine or daylight or other high temperature source
of radiant heat since in such circumstances buth the motor and the shade soon.
acquire the temperature of the surrounding objects and owing to the absence of a.
difference of temperature between the two there will no motion of the vane.
Although the apparatus is intended to work with air at ordinary atmospherio
pressure it will still operate but less perfectly if the enclosed air be rarefied, or if
it be compressed.
Several motors may be placed under one shade and be simultaneously driven by
radiant heat from the outside.
The next part of my invention refers to the artificial communication of heat to
the motor shown in Figuro 1 for the purpose of causing the motor to work in n
closed room or for re-inforcing its action out of doors.
Figures 9 and 10 show how heat may be communicated to the fluid within tho
shade by means of an electric glow lamp. In Figure 9 the fan or vane E revolves
on the point of a needle fixed to the apex of a glow lamp Q within the chimney A.
In Figure 10 the vane E is pivoted as described in reference to Figure 1 and the
lamp Q is suspended within the chimney A from a thiu wire or bridge Q' so that
the air can pass it on all sidos.
Figure 1 shows a construction in which the heat is conducted to the interior of
the shade by means of a metal bar which is heated at its remote extremity. R is a
short vertical tube passing through the base of the apparatus and projecting
slightly into the lower end of the chimney A. The said tube is covered with
non-conducting material. The vane E is supported as usual on a thin metal
bridge. The conducting bar not shown in the figure is coated with non-conducting
material except at its two extremities. One of these is introduced into the tube R.
and the other is heated by a lamp flame or in any other suitable way. Instead
of a short tube R I sometimes employ a piece of solid copper or other good.
conductor of heat surrounded by non-conducting material. In this case the
conducting bar is brought into intimate contact by screwing or otherwise with the
lower end of the said solid conductor.
Figure 12 illustrates a method of communicating heat to the motor by means
of liquids or guses. S is a chamber carefully covered with non-conducting
material except at the top which is left open or which is closed with a thin metal
plate. Two metal pipes S', S united at their upper extremities are arranged
within the said chamber. The said pipes are connected to two tubes S, Sof
non-conducting material or two tubes suitably covered with such material which
tubes are continued as far as the source of heat where they are connected to a
metal chamber or coiled pipe S through which the contained liquid or gas receives
heat from a suitable source. Instead of being placed in a special chamber S the
pipes S', S may be fixed within the chimney A which in that case should be
covered with non-conducting material.
Figure 13 illustrates a form of instrument which may be worked by the heat of
the band or by heat developed by electricity. T is a coiled metal tube com-
municating at its upper end with the base of the chimney A and at its lower end
with two pipes T T which open into the base of the shade G at points external
to the chimney. The fan or vane E is carried as above described on a needle
supported by a thin metal bridge. On grasping the pipe T with the band air will
asceud through it and through the chimney A and descend by the sides of the

page_text: On the other hand
by grasping the pipes T T with both hands air will be caused to ascend in the
said pipes and descend by the chimney A and pipe T thus causing the vane to
revolve in the opposite direction. By making the pipe T of an imperfect conductor
of electricity, insulating it electrically at top and bottom from the rest of the
instrument and including it in the circuit of a conductor carrying a strong current,
the said pipe will be warmed by the current and the vane will be caused to rotate.
Instead of making the pipe T actually a part of an electrical conductor it may be
surrounded by a coil of wire or be embedded in insulating enamel which receives
hest from an electrical conductor also embedded therein. By making the
pipes T T of, or coating them with, non-conductors of heat while the pipe T is
naked the vane may be worked by dipping the pipes in warm water, chemical
solutions or other source of heat.
shade and the pipes T T and will cause the vane E to rotate.
In the forms of instrument shown in Figures 9 to 13 the speed of rotation will
vary with the difference of temperature existing between the vano aud the glass
shade or cover and with the pressure to which the enclosed air is subjected and the
speed may be increased either by raising the surface temperature of the vane, or
When the surface
reducing that of the shade, or by increasing the pressure.
temperature of the vane is kept at a constant level above that of the shade the
speed will be constaut also provided the barometrical pressure be constant. If
there be no difference of temperature between the shade and the vane no rotation
will occur, and there will also be no rotation if the temperature of the shade
exceeds that of the vane because there is no outlet for heat radiated inwards
unless ice or a freezing mixture be suspended in the chimney A or the chimney be
packed in ice, or other means be taken to absorb heat internally. When this is
done the rotation will be in the reverse direction to that which occurs when the
internal temperature exceeds the external temporature.
In adapting the instrument for use in calorimetry the glass shade may be main-
tained at a constant temperature by carefully packing the same in ice but this
method is inconvenient as the ice packing which requires to be very perfect renders
a view of the fan or vane difficult to obtain. A method which may be more
conveniently adopted is shown in Figures 14 and 15 where the glass shade or
gas-jar G is furnished with a long neck and a mouth provided with a tightly fitting
stopper G and is made watertight in a water tauk U which has at least two of
its sides of glass.
U is a water-tight vessel upon which the tank U stands the two vessels
communicating by means of a pipe U'in which is a tap for closing the communication
when desired. U is a mid-feather which causes the water coming from the tank U
to pass under the top plate of the vessel U' and then down and under the mid-
fenther before reaching the waste outlet U. U is a tube, passing through the
vessel U and communicating with the interior of the shade G, and serving for the
introduction of gases or conducting wires into the shade G or for keeping the air
or gas in the said shade at atmospheric or any desired pressure. V is a tank
kept well supplied with pounded ice and having a coustant stream of water
flowing through it. The water escapes by the outlet V₁ and enters the
vessel U as indicated. The tauk is preferably divided into two compartments
by a central partition V having one or more holes in its lower part so
that the water entering the tank from the supply pipe V must sink through
one body of ice and rise through the other before it escapes. Should the
supply vary in temperature from time to time the ice filter will rectify inequalities
and ensure a feed at constant temperature into the tank U. If, as is sometimes
the case, the temperature of the water coming from the supply mains of a town remains
constant for several hours at a time the ice tank V may be dispensed with, the water
being then fed directly into the tank U. Before the tank U is mounted upon the
vessel U the motor above described but having its chimney A thickly covered with
non-conducting material is placed on the vessel U¹ so as to be covered by the

page_text: shade G. The joint between the vessels U and U is mado air-tight by india
rubber packing or by any other suitable means. Two sensitive thermometers not
shown in the figure are placed one with its bulb in the running water in the tank U
and the other with its bulb inside the chimney A. With this apparatus various
experiments may be performed and measurements made. To preparo the
calorimeter for use, the water is turned on and when the tank U and vessel U
have become full the ontlet U is opened and a copious stream of water is allowed
to run through the apparatus without intermission and regulated so that the tank U
remains full. Soon after turning on the water the fan or vane E will begin to
rotate and will continue in motion until the temperature of the whole of the
apparatus covered by the shade G. which temperature was initially that of
the room, has been reduced to about three tenths of a degree Fahrenheit above
that of the water running through the tank U. The fan or vane will then stop
but the mercury of the inner thermometer will continue to fall until it marks only
one or two tenths of a degree Fabrenheit above the temperature of the water. If
now a leaden box W heated to any desired degree above the temperature of the
circulating water he suspended within the chimney A by means of a silk thread
from the stopper G the rotation of the vane will re-commence aud will continuo
until the temperature of the apparatus including that of the leaden box has been
again reduced to about three-tenths of a degree Fahrenheit above that of the
circulating water. The lenden box being hung in the chimney cannot part with its
hent except by radiation to the motor surfaces and these owing to the outer ensing
of non-conducting material cannot radiate the heat they thus receive outwards, to
that practically all the heat stored in the leaden box is utilised in expauding the
air within the chimney A and so causing a convection current to circulate upwards
through the motor and downwards by the glass walls of the shade G, by means of
which the heat stored in the box W is ultimately all conveyed to the circulating
water and carried off. The total convective energy of the heat stored in the box W
is ascertained by counting the rotations of the vanc E from the moment of sus
pending the leaden box in the chimney until rotation ceases. If now the leaden
box be removed and after the inner thermometer indicates that the inside tempera-
ture is again at the point above that of the circulating water at which it stood
when its leaden bux was introduced a copper box of exactly the same shape and
size as the leaden box and made up to the same weight by being constructed of
stouter metal or by having pieces of copper attached to its inside (no solder being
used) be beated to exactly the same degree as was the leaden box and suspended
in the same manner within the chimney A it will be found that the convective
nction as ascertained by counting the rotations of the vane is very much increased.
An aluminium box similarly prepared will drive the vane longer still, and it will bo
found that iron, zine, tin and the other metals will each yield a specific number of
revolutions. On comparing the number of revolutions ascertained in this manner
for each metal tested it will be found that the numbers are in direct proportion to
the specific heats of the metals. Other substances than metals may be tested but
it is desirable that uniformity be observed in shape and size of the pieces used in
order that the resistance offered to air currents by the obstacle in the chimney may
be the same for each substance. If the metals to be compared are arranged in
bare, ruds or wires they may be hung in the chimney, and cooled down with the
rest of the apparatus and then heated by passing currents of electricity through
them from outside conductors. The danger of losing heat during the transfer of
the substance from the heater to the calorimeter may be thus avoided. Liquids
and substances which cannot be shaped into boxes or bars may be suspended in a
containing vessel the value of which whon empty as measured in rotations has been
carefully ascertained. The deduction of these rotations from the total result
obtained from a box and its contents will give the heat value of the contained
substance. This method is not, however, so nccurate as that previously described.
The specific heat of liquids and gases may be experimented on by forcing them at
B

page_text: a known temperature and in known quantity through a tube coiled in the chimney A
the temperature of the tube and of the rest of the apparatus having been previously
reduced to that of the running water or nearly so.
Instead of suspending the substances in containing vessels or tubos in the
chimney they may be tested by being placed in a thermally-insulated chamber at
the base of the motor such as that shown at S in Figure 12. In this case the said
chamber together with the rest of the apparatus must be previously cooled to the
temperature of the running water.
The form of instrument shown in Figure 13 may also be used for specific heat
measurements, the tube T being the receptacle for the substance to be treated.
This tube which may be varied in shape and size is previously cooled down to the
temperature of the running water.
The calorimeter shown in Figures 14 and 15 may be used to measure the com-
parative heat-retaining power of textile fabrics or non-conducting compositions.
If the chimney A bo.of copper or other good conductor and if its non-conducting
covering be removed, some of the hent from the box W after being radiated to
the inner surfaces of the chimney A will pass by conduction to the outer surfaces
and there set up exterior convection currents which will have no effect on the
vane E except of disposing of some of the heat which if retained in the chimney
would have made itself apparont in revolutions. If the rotations produced by a
certain amount of heat placed in a naked chimney be counted and the experiment
then repeated with the chimney clothed in ashestos cloth it will be found that the
number of rotations produced by the same amount of heat has been considerably
increased owing to the asbestos cloth confining the heat to the chimney and com-
pelling it to escape almost wholly from the inside surfaces and so become expended
in creating convection currents, which rotate the vane. If woollen cloth be used
an intermediate result will be obtained by reason of the interception of heat being
less perfect, while other materials, as linen, silk, cotton, fur, boiler composition, and
the like when applied to the chimney in equal thicknesses will yield different
rotation values in proportion to their capabilities for preventing the escape
of heat.
The heat conductivity of threads and thin wires may also be compared by
suspending the source of heat successively by threads and wires of the same gauge
and length but of different materials from the stopper G' which stopper in this case
is preferably made of metal and is in contact with the running water. Very little
heat will escape over a silk thread but a good deal over a metal wire, the varying
results becoming apparent in the different number of revolutions resulting from the
same amount.of.introduced heat, the period of rotation being greater the better the
heat insulating power of the thread. In these tests the chimney A should be
carefully covered with non-conducting material.
Interesting convection experiments may be made by filling the shade G,
Figures 14 and 15 successively with different gases and vapours each of which, so
far as my investigations have yet extended, is found to possess a specific rotation
value for the same amount of introduced heat.
The apparatus shown in Figure 11 may be employed for testing or demonstrating
the heat conductivity of different rods or tubes by introducing one end into
the short tube R while the other is heated in any suitable way, the effects
on the vano being noted. For this purpose the instrument should be surrounded
by running water as indicated in Figures 14 and 15. Similarly, the arrangements
shown in Figure 12 may be employed for comparing the heat conductivity of
liquids or gases contained in tubes. By arranging the tubes horizontally, vertically
upwards or vertically downwards the comparative conductivity of a liquid, gas or
vapour horizontally, and upwards or downwards may be demoustrated.
The arrangement shown in Figure 10, when used with running water as described
in connection with Figure 14, may be used to compare electric glow lamps and as
an electricity meter. Lamps of the same candle power should yield the same
number of rotations per minute when working at normal current and under the

page_text: same barometrical pressure, aud the speed of rotation will vary with the current
passing through the lamp filament or through a high resistance cuil placed in the
chinney A. A known current of electricity passing for a known time through
such a lamp or coil of wire and then discontinued will cause a definite number of
rotations. It is therefore easy to calibrate an instrument so that the current
passing may be known by the number of revolutions per minute made by the
vane.
The instrument shown in Figure 13 may likewise be used as an electricity
meter when surrounded by a stream of running water of known and invariable
temperature.
So far un device for automatically registering the ratations of the vane has been
described. When the motor is made of large size, with a fun pivoted both at top
and bottom, the spindlo may be arranged to actuate a delicate in chanical counter
or to alternately open and close a pair of light electrical contacts by means of
which a record of the revolutions may be preserved. When the vane is pivoted
on one neelle point the plan shown in Figure 16 may be adopted. A magnetised
needle Y is fixed to the vane E and a narrow rectangular coil of fine wire is
arranged vertically to enclose the vane while not sensibly diminishing the air-way
of the chimney A. The connecting wires load from the coil Y to the place where
it is desired that the rotations shall be made visible. At that place a sensitive
dead-beat reflecting galvanometer of the Thomson or D'Arsonval type is connecte:
to prolongations of the connecting wires. The inagnetized needle Y rotating
with the vane within the coil will induce alternating currents in the coil which will
become visible in the receiving galvanometer as dellections alternately to the right
and left. Instead of a reflecting galvanometer a Thomson's syphon recorder may be
used and a continuous record of the rotations obtained. In this way an instrument
may be constructed to serve as a sunshine recorder. But the adoption of any
recording device reduces the sensitiveness of the vane and none such should be
employed when it is required to work with small differences of temperature.
The various instruments hereinbefore described whether driven by natural radiant
heat or artificially communicated heat may be used for advertising purposes by
painting letters, words or devices on the vanes, stands or shales or by employing
the rotation of the vane to alternately disclose and obscure letters, words or devices.
Or two or more vanes and chimneys may be placed under one shade or two or more
vanes may be placed one above the other in the same chimuey each lettered with a
word forming part of a sentence.
By painting the vanes with, or forming them to resemble, animals, national flags,
coaches, railway trains, or the like, the instrument in several of its forms may be
used as an instructive philosophical toy.
Combined with electric glow or other lamps the instrument may be made into
attractive forms of table and suspended lamps.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A motor comprising a fan or vaue mounted to rotato within a chimney
enclosed within a glass or similar shade, substantially as described and for the
purposes specified.
2. In such a motor the devices for storing heat substantially as, and for tho
purposes, described.
3. The device for conveying heat to the motive fluid within the shade,
substantially as described with reference to one or other of Figures 9 to 13
of the accompanying drawings.
4. The method of mensuring the specific beat of substances, and the conductivity
for heat of fabrics threads and wires, in the above described apparatus, substantially
as set forth.
6. The apparatus constructed substantially as described with reference to one

page_text: or other of the forms illustrated in the accompanying drawings, for the purposes
specified.
Dated this 25th day of January 1897.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.