IMPROVEMENTS IN WITHERING AND DESICCATING THE LEAVES AND FLOWERS OF PLANTS AND OTHER VEGETABLE SUBSTANCES, AND IN THE APPARATUS TO BE EMPLOYED THEREIN
Year: 1868

page_text: LETTERS PATENT to Benjamin Dickinson, of Hopetown, Darjeeling,
India, Tea Planter, for the Invention of "IMPROVEMENTS IN WITHERING
AND DESICCATING THE LEAVES AND FLOWERS OF PLANTS AND OTHER VEGETABLE
SUBSTANCES, AND IN THE APPARATUS TO BE EMPLOYED THEREIN."
Sealed the 9th March 1869, and dated the 19th September 1868.
PROVISIONAL SPECIFICATION left by the said Benjamin Dickinson,
at the Office of the Commissioners of Patents, with his Petition,
on the 19th September 1868.
I, BENJAMIN DICKINSON, of Hopetown, Darjeeling, India, Tea Planter,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
WITHERING AND DESICCATING THE LEAVES AND FLOWERS OF PLANTS AND OTHER
VEGETABLE SUBSTANCES, AND IN THE APPARATUS TO BE EMPLOYED THEREIN," to be
as follows:-
This Invention has for its object the more uniform, perfect, and
economical treatment of the leaves of the tea plant, and the leaves
and flowers of other plants requiring to be similarly prepared by
withering and desiccation. For these purposes I employ a current of
heated air admitted under regulation as to its temperature, volume, and
Price 8d.1

page_text: velocity, so as to come in contact with, pass through, amongst, and over
the materials to be treated or operated upon.
In applying my Invention for the purpose of withering and desic-
cating the leaves of the tea plant I prefer to construct and arrange the
apparatus in the following manner :-I construct a series of trays or
shallow boxes without covers, by preference in wood, and of the same size,
capable of fitting into and side by side the one with the other inter-
changeably, and each having a bottom of open canework, upon which
the green leaves to be treated are placed to a suitable depth or thickness
to allow of the air passing freely up through and amongst the leaves to
be operated upon. These trays or open top-boxes are placed upon a
frame of woodwork, or upon a long open-top trough with closed ends,
and, say, of such dimensions as would be capable of taking two of them
in width, and two or more in height, and several in the length of the
frame or trough, and so fitting the one set of trays against the other
and upon each other that the heated air driven into the trough can
only escape through the bottoms of the trays containing the leaves, and
so through the leaves, and in its passage withering and desiccating the
leaves requiring to be so treated.
Where I employ two or more trays in height one above the other I place
the green leaves in the upper trays of the horizontal series or row, and
when the leaves have become desiccated or freed from moisture I replace
the top series of trays, when there are three trays in height, with trays
containing the fresh plucked or damp leaves and withdraw the lowest
series, so that the third or uppermost becomes the second, and the
second the lowest; but I prefer generally only to employ two tiers of
trays in height, and whether there be two or more in width, and eight
or ten in the length of the frame, or fewer in number. Into the open-
top box or trough the heated air is admitted by an opening or pipe at
one end, and it thereupon ascends first through the cane bottom of aud
amongst the partially dried leaves in the lower series of trays, and then
through the next or upper trays and their contents, and passes freely off
from thence into the air.
I prefer for most purposes to divide the box or trough longitudinally
where there are two or more rows of trays in the width of the apparatus,
and also to introduce "baffle boards" or "bridge pieces," so as to
regulate the length and direction of the travel or movement of the
current of heated air, and so that the contents of the trays furthest

page_text: removed from the source of the hot air may be sufficiently operated
upon. The trays may, by having their sides suitably rebated or grooved
to fit one another, and a correspondingly grooving or rebating on the
upper edge of the longitudinal or side pieces, be so slid or moved from
one end of the trough or box to the other as to readily admit of the
interchange of their positions being effected by sliding, and without
lifting them each time.
For the purpose of heating the large volume of air required to perform
the operation of withering and desiccating the leaves of the tea plant
contained on the openwork bottom trays or boxes I have described,
I construct a tubular boiler-like vessel, or a case or vessel containing
either tubular or any other convenient form of flue or flues, through
which or amongst which the air to be heated is driven by means of a
fan blower, whilst the fire acts upon the other surface of the metal tubes
or flues.
A box or boiler containing flat sheet spaces or "gills" is a
convenient form of heater or heating chamber. The air to be heated is
driven into this chamber or vessel by means of a rotary fan or blower,
which may be turned by hand, or by animal, steam, or other power. After
the air has been heated to a sufficiently high temperature it is allowed
to enter the trough or box upon which the trays are mounted, and it
can then only escape through the trays and their contents, and by this
means the required effect is produced upon the material to be operated
upon. By means of throttle and shut-off valves introduced in the cold
air admission pipe and into the hot air discharge pipe, in conjunction with
the speeding of the fan blast and the firing up or heating of the furnace,
the more exact regulation can be obtained and the same results repeated,
the whole of the operations being thus under the most perfect control.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Benjamin Dickinson in the Great Seal Patent
Office on the 18th March 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENJAMIN
DICKINSON, of Hopetown, Darjeeling, India, Tea Planter, send greeting.
day of
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the
, in the
year of our Lord One thousand eight hundred and sixty-eight, in the

page_text: thirty-first year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Benjamin Dickinson, Her special
licence that I, the said Benjamin Dickinson, my executors, adminis-
trators, and assigns, or such others as I, the said Benjamin Dickinson,
my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN WITHERING AND DESICCATING THE LEAVES AND FLOWERS
OF PLANTS AND OTHER VEGETABLE SUBSTANCES, AND IN THE APPARATUS TO BE
EMPLOYED THEREIN," upon the condition (amongst others) that I, the
said Benjamin Dickinson, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Benjamin Dickinson, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in
and by the following statement in writing, reference being had to the
accompanying Sheets of Drawings, that is to say:-
This Invention has for its object the more uniform, perfect, and
economical treatment of the leaves of the tea plant, and of the leaves
similarly prepared by
and flowers of other plants requiring to be
withering and desiccation. For these purposes I employ a current of
heated air admitted under regulation as to its temperature, volume, and
velocity, so as to come in contact with, pass through, amongst, and over
the materials to be treated or operated upon.
In applying my Invention for the purpose of withering and desic-
cating the leaves of the tea plant I prefer to construct and arrange the
apparatus in the following manner :-I construct a series of trays or
shallow boxes without covers, by preference of wood, and of the same
size, capable of fitting into and side by side the one with the other
interchangeably, and each having a bottom of open canework, upon
which the green leaves or other materials to be treated are placed to a

page_text: suitable depth or thickness to allow of the air pressing freely up through
and amongst the leaves to be operated upon. These trays or open-top
boxes are placed in or upon a frame of woodwork or open-top trough, or
a frame of woodwork upon an open-top trough of brick or earth with
closed ends, and of such dimensions as would take one or two in width,
one, two, or more in height, and several in the length of the frame
or trough, and so fitting the one set of trays against the other and one
layer of trays upon another that the heated air passed into the trough
can only escape through the bottoms of the trays containing the leaves,
and so through the leaves, in its passage withering and desiccating the
leaves required to be so treated.
Where I employ two or more trays or layers of trays in height, the
one above the other, I generally prefer to place the green leaves in the
upper trays of the horizontal series or row, and when the leaves have
become partially desiccated or freed from moisture I replace the top
series of trays (when there are three trays in height) with trays con-
taining fresh plucked or damped leaves and withdraw the lowest series,
so that the third or uppermost becomes the second, and the second the
lowest; but I prefer generally only to employ two tiers of trays in height
whether there be two or more in width, and eight or ten in the length
of the frame, or fewer in number. Into the open-top box or trough the
heated air is admitted through a pipe or opening at one end, and there-
upon it ascends first through the cane bottom of and amongst the
partially dried leaves in the lower series of trays, and then through the
next or upper series of trays and their contents, and passes freely off
from thence into the atmosphere.
I prefer for most purposes to divide the box or trough longitudinally
where there are two or more rows of trays in the width of the apparatus,
and also to introduce "baffle boards" or bridge pieces, so as to regulate
the length and direction of the travel of the current of heated air, and
so that the contents of the trays furthest removed from the source of
heated air shall be properly operated upon. The trays may, by having
their sides suitably rebated or grooved to fit one another, and a corre-
sponding grooving or rebating on the upper edges of the longitudinal or
side pieces, be so slid or moved from one end of the trough or box to
the other as readily to admit of the interchange of their positions being
effected by sliding, and without lifting them each time.
For the purpose of heating the large volume of air required to perform

page_text: the operation of withering and desiccating the leaves of the tea plants
contained in the open-wcrked bottom trays or boxes I have described
above, I construct a tubular boiler-like vessel, or a case or vessel con-
taining either tubular or any other conveniently formed flue or flues,
through which or amongst which the air to be heated is driven by means
of a fan blower, whilst the fire acts upon the other or outer surfaces of
the metal tubes or flues. A boiler or box containing flat sheet spaces
or "gills" is a convenient form of heater or heating chamber. Other-
wise I also employ a series of pipes placed in a flue, the air to be heated
being forced through such pipes whilst the heated gases from a furnace
act on their exterior surfaces. The air to be heated may be driven into
the heating chambers or pipes by means of a rotary fan or any other
description of blower, which may be worked by hand, or by annual,
Steam, or other motive power. After the air has been heated to a
sufficiently high temperature it is caused to enter the box or trough
upon which the trays are mounted, and it can then only escape through
the bottom of the trays and through or amongst the contents thereof,
by which means the required effect is produced upon the materials to
be operated upon. By means of throttle and shut-off valves introduced
in the cold air admission pipes and into the hot air discharge pipe, in
conjunction with regulating the speed of the fan blower and the firing
up or heating of the furnace, the more exact regulation may be obtained
and the same results repeated, the whole of the operations being thus
under the most perfect control.
The Drawings hereunto annexed shew some of the manners or modes
in which I prefer to construct the apparatus in accordance with my
Invention, and how such mechanical apparatus is to be used or employed,
also how my said Invention is to be performed and carried into effect.
Figures 1, 2, and 3, Sheet 1, show one of the arrangements of
apparatus which I employ in carrying my Inventions into effect.
Figure 1 is a slide elevation, Figure 2 a transverse section on the line
A, A, and Figure 3 a horizontal section of the apparatus. Similar
letters in the different Figures refer to corresponding parts. In this view
the case a contains a steam turbine which is actuated by steam from
the boiler K which passes to the turbine through the steam pipe C, being
controlled by the stop-cock J, and the exhaust steam escapes through
the discharge pipe B. Upon the vertical axis upon which the turbine is
carried there is fixed a fan blower enclosed in a case D, so that the fan

page_text: blower is driven by the steam turbine or rotary engine, the whole
a frame or
arrangement of turbine and blower being mounted on
pedestal e. The rotation of the fan blower causes air to be driven
through the cold air supply pipe f into and through the heating
pipes g. 9, 9, (shewn by the dotted lines in the side elevation, Figure 1),
and thence into the hot air supply pipe h, h, whence it passes into the
open-top trough n, upon which are mounted the various rows and tiers
of cane bottomed trays o in which the leaves or other materials upon
which it is required to operate are placed, and which trays are supported
and kept in position by the framework p. The boiler is shewn as of
the ordinary Cornish form having one flue tube passing through it, in
which is placed the furnace closed by a furnace door m. The products
of combustion from the furnace in the flue tube of the boiler pass
thence into the chamber w and thence through one of the flues r and s,
as circumstances may require, into the up-take t, and thence into the
atmosphere through the chimney i; the direction taken by the heated
products of combustion after leaving the chamber w is determined by
means of the dampers u and v, which control the entrances respectively
to the flues and s. The heating pipes 9, 9, 9, pass through the flue s,
and are supported by cross pieces bedded in the masonry, within which
the flues are formed. x is a water tank to supply the boiler k, and it is
placed at a sufficient height to allow the head or pressure of water to
overcome the pressure of steam in the boiler k, so that the wat:" may
flow by its own gravitation into the boiler when required. The ta: k is
supported upon framing y, y. The feed water flows into the boiler
through the feed pipe z, its supply being regulated by the stop valve =¹,
which stop valve is controlled by the level of water in the boiler acting
upon a float attached to the wire, so that when the water level in the
boiler falls the stop valve is opened to admit the water and vice versa.
y is an ordinary safety valve.
Figure 4, Sheet 1, shows an end view of an open-top trough formed
in brickwork or masonry, and of the cane bottomed boxes or trays
mounted thereupon. When it is required to bring the apparatus or
mechanical appliance into operation I pursue the following course :-
The feed water tank x being sufficiently full of water the water level in
the boiler will adjust itself by means of the self-acting supply valve 2¹
actuated by the float; I then open the damper u keeping the damper v
closed, and light a fire in the furnace, whence the products of com-

page_text: bustion pass through the flue into the chimney i; this direction is
given to the heated gases at first because if they were allowed to
circulate around the heating pipes 9, 9, 9, when no cold air is being
driven through the said pipes they would be liable to being very rapidly
corroded or "burnt out." " As soon as a sufficient pressure of steam has
been raised in the boiler k to work the fan blower, the stop-cock j may
be opened as far as is necessary to impart the proper speed to the flan
blower, which will then commence to drive air into the pipes 9, 9, 9.
I now close the damper u and open the damer, thereby directing
the gaseous products of combustion upon the outer surfaces of the
pipes g. 9, 9, which absorb a portion of the heat and transmit it to
the air which is being driven through them by the fan blower. The
temperature attained by the air passing out of the pipe h, h, into the
trough n being tested and found proper for the preparation of the leaves,
the trays o, o, o, may be charged and the treatment of their contents
proceeded with. The volume of air passed through the heater may be
regulated by the speed of the fan blower which is controlled by the
stop cock on the steam pipe c, and the temperature of the hot air is
regulated by the heat of the furnace in the flue tube 7 of the boiler k.
Sheet 2 illustrates another form of apparatus which may also be
employed in putting my Invention into practice. Figure 1 is a longi-
tudinal section of the apparatus; Figure 2, a plan; Figure 3, a side
elevation of the fan and air heating apparatus; and Figure 4, a transverse
section of the furnace and heating chamber. A is a steam engine used
to propel the fan blower, which engine is supplied with steam from
the boiler B. From the driving wheel C of the engine A a strap or
band f, f, passes to a smaller pulley or rigger t fixed on the spindle
of the fan blower d; the blower when actuated by the engine draws
in cold air and propels it through the pipe or passage into the heating
tubes h, h, whence it passes through the hot air supply pipe m into the
open-top trough n, and thence, through the cane-bottomed trays o carried
on the farm p and their contents, into the atmosphere; g, shows the
fire-grate of the heating furnace from whence the flames and heated
gases pass around and amongst the heating tubes h, k, in the casing i,
and thence the products of combustion pass away by the chimney k.
The furnace g is set in masonry F, F, which also serves as a bed for the
fan blower and the heating chamber i with its contained heating
tubes h, h.

page_text: Figure 5, Sheet 2, is an end view of the open-top trough with the
trays o mounted on it. When it is desired to bring this apparatus into
operation steam is first raised in the boiler B until the pressure is
sufficient to drive the engine A, and so actuate the fan blower d; this
done, the fire may be lit ou the furnace grate g. The fan blower being
now set in motion air will be forced through the treating pipes h, h,
into the trough n, and thence through the trays o and their coutents.
Instead of employing a fixed Cornish boiler and a coil or series of
heating pipes set in brickwork. as shown, Figures 1, 2, and 3, Sheet 1,
I prefer for the temporary garden use, and where the reinoval of the
descicating apparatus from one garden to another is desired, to use or
employ a portable steam boiler or a boiler mounted upon a wheel
carriage having a coil of pipes fitted within a suitably enlarged smoke
box, and having upon the side of the boiler or in other convenient
position the steam motor or engine and a rotary fan blast conveniently
placed so as to be driven by the engine, or instead thereof to construct
the heating chamber within an iron casing which I mount upon wheels;
the furnace being contained within the casing, the firing or charging is
performed at one end, and the discharge of the heated air may be
effected at the opposite end; upon such a heating apparatus I place a
small steam generator or boiler, and use or employ a portion of the
heat generated within the furnace of the hot air heater, which is capable
of being shut off entirely or partially, so that the generation of the
steam is thoroughly under control. The form of the heating spaces of
the chamber or heater may be varied, and either be flat or circular pipes,
or sheet spaces, but in every case the products of combustion from the
furnace must not be permitted to mix with the air to be heated, nor in
any case must the metal surfaces of the tubes or other spaces through
which the air has to pass be allowed to become so highly heated as to
impart to the leaves to be desiccated a burnt or other injurious flavor.
I have shown in Sheet 1, Figures 1, 3, and 4, the desiccating throughs
and trays suitable for a permanent establishment, and although on the
plan Figure 3, as well as on the section Figure 4, only one series of three
sets of trays in length each composed of the three trays in depth are
there arranged in direct communications with the hot air discharge pipe.
I have herein-before mentioned that the number of sets of trays may
be increased, and I prefer that they should be set side by side and repeated
in width rather than extended in their length, and that a distribution

page_text: pipe at right angles to the hot air discharge pipe h may be introduced
at the head of the pits or troughs so as to command each set of trays and
their contents independently, and by means of shut-off valves regulate
the admission of the hot air when the trays are in use, or shut off and
exclude the hot air entirely when the trays are out of use. Across the
trough and at various parts of its length may be introduced moveable
bridges or baffle boards by which the forward motion of the air may be
checked or regulated.
Although I have shown the troughs for receiving the hot air from the
discharge pipes as of brick or other such material formed within an
excavation in the ground, the desiccating chamber may be constructed
of iron, wood, or any other suitable material, or a burnt clay vessel or
an earthenware plan, glazed or unglazed, and mounted or fitted within
a wooden box or case fitted with axles beneath it so that it may be
raised, and wheels fitted upon the axles for the purpose of facilitating
the removal of the desiccating apparatus from one garden to another,
so that when the apparatus has arrived at its destination the wheels
may be removed and the apparatus lowered on to the ground so as to
be at a convenient height therefrom to enable the operators to work
handily and have the trays under control, that their removal and inter-
charge may be effected with facility, as the process of desiccating or
drying the leaves of the tea plants can only be properly effected by very
careful and delicate management and constant watching the progress
of the treatment.
Having now herein described my Invention and several modes or
methods of putting the same into practice, and in the accompanying
two Sheets of Drawings illustrated some of the methods I prefer to
construct and arrange the various parts of the apparatus, I wish it
to be understood that I do not intend to claim the use or employment
of hot air impeller nor heating pipes employed for the purpose of
desiccating vegetable and other substances, but what I claim is,-
First. The improvements in withering and desiccating the leaves and
flowers of plants and other vegetable substances, as herein described.
Second. The improvements in withering and desiccating the leaves of
the tea plant, and the apparatus employed for such purpose, as herein
described and set forth.
Third. The apparatus here described, and as illustrated in Sheets 1

page_text: and 2 of the accompanying Drawings, for the purpose of withering and
desiccating the leaves of the tea plant, as herein set forth.
Fourth. The use or employment of trays having openwork bottoms of
cane or other suitable material in conjunction with the use or employ-
ment of hot air for the purpose of withering or desiccating or partially
desiccating the leaves of the tea plant, as herein described and illustrated
in the accompanying drawings.
Fifth. The combination of a hot air trough, pan, or vessel, whether
fixed or portable, as herein-before described, with interchangeable trays
having open bottoms of comework or other suitable material fitted
thereonto when used or employed for the purposes and in the manner
herein described.
In witness whereof, I, the said Benjamin Dickinson, have hereunto
set my hand and seal, this Twenty-second day of October, in the
year of our Lord One thousand eight hundred and sixty-nine
eight.
Witness,
M. FREDERIC ROGERS,
19, Salisbury St.
Strand.
BENJAMIN DICKINSON. (L.B.)