IMPROVEMENTS IN DESICCATING THE LEAVES AND FLOWERS OF PLANTS AND OTHER VEGETABLE SUBSTANCES, AND IN THE APPARATUS TO BE EMPLOYED THEREIN
Year: 1865

page_text: LETTERS PATENT to Allan Lawrie M Gavin, of Bucklersbury, in the
City of London, for the Invention of "IMPROVEMENTS IN DESICCATING
THE LEAVES AND FLOWERS OF PLANTS AND OTHER VEGETABLE SUBSTANCES,
AND IN THE APPARATUS TO BE EMPLOYED THEREIN."-A communication from
abroad by Benjamin Dickinson, of the Firm of Ahmuty & Co., of
Calcutta.
PROVISIONAL SPECIFICATION
left by the said Allan Lawrie McGavin
at the Office of the Commissioners of Patents, with his Petition, on the
20th October 1865.
1, ALLAN LAWRIE MCGAVIN, of Bucklersbury, in the City of London, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN DESIC.
CATING THE LEAVES AND FLOWERS OF PLANTS AND OTHER VEGETABLE SUBSTANCES,
AND IN THE APPARATUS TO BE EMPLOYED THEREIN," a communication to me from
abroad by Benjanin Dickinson, of the Firm of Ahmuty and Co., of Calcutta,
to be as follows.
This Invention has for its .object the more uniform, perfect, and economical
drying, or desiccation of the leaves of the tea plant, and the leaves and
flowers of other plants requiring similar treatment, by the application of a
current of heated air admitted under regulation as to its temperature and
velocity in contact with the material or materials to be treated, which mate-
[Price 8d.]

page_text: rials for the purpose of being more effectively acted upon are placed within
a cylinder or drum, the periphery of which is composed of wire gauze or other
suitably perforated metallic covering, and is caused to revolve or rotate at a
suitable speed by means of a handle, drum, or wheel fixed upon a spindle or
axis. The drum is fitted with a door or moveable cover piece, by which the
materials to be treated are placed within the cylinder, and by means of which
the materials after they have been treated may be removed from the cylinder.
The cylinder or drum is mounted within a box or case, the bottom of which
is to be closed by a perforated plate, whilst the top is fitted with a moveable
cover that it may be left wholly or partially open whilst the desiccating
process is being carried on. To the bottom of the box or case is fitted a
funnel-shaped hopper, which acts as a distributing chainber for the hot air,
it being connected at its lower end to the hot-blast pipe in connection with
the furnace or heater, which may be of any suitable construction and placed
in any convenient position for the purpose of heating the air as it is driven
tbrough or drawn through by means of a fan blast. By means of throttle
valves the admission of air may be regulated to the fan or other contrivance
for forcing or drawing the air through the heater. Similar valves may be
applied to the blast pipe between the heater and desiccating apparatus. The
quantity of air to be heated and driven through the desiccating apparatus may
also be regulated by a change of speed of working, as also the number of
rotations of the cylinder or drum may be varied during the progress of the
desiccating operation, so as to bring them into correct relation with the tem-
perature as well as the quantity of air driven through and amongst the
materials under treatment.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Allan Lawrie McGavin in the Great Seal Patent Office on
the 19th April 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALLAN
LAWRIE MGAVIN, of Bucklersbury, in the City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of October, in the year of our Lord
One thousand eight hundred and sixty-five, in the 29th year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Allan Lawrie McGavin, Her special license that I, the said Allan
Lawrie M°Gavin, my executors, administrators, and assigns, or such others as I,

page_text: the said Allan Lawrie McGavin. my executors, administrators, or 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 "IMPROVE.
MENTS IN DESICCATING THE LEAVES AND FLOWERS OF PLANTS AND OTHER VEGETABLE
SUBSTANCES, AND IN THE APPARATUS TO BE EMPLOYED THEREIN," a communication
to me from abroad by Benjamin Dickinson, of the Firm of Achmuty & Co..
of Calcutta. upon the condition (amongst others) that I, the said Allan Lawric
McGavin, my executors or administrators, by an instrument in writing under
my hand and seal, or under the hand and seal of one of them, should par-
ticularly describe and ascertain the nature of the said Invention, 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 Allan Lawrie McGavin, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed. to be particularly described and ascertained in and by
the following statement and accompanying Drawings:-
This Invention has for its object the more uniform. perfect. and economical
drying or desiccation of the leaves of the tea plant. and the leaves and flowers
of other plants requiring similar treatment. by the application of a current of
heated air admitted under regulation as to its temperature and velocity in
contact with the material or materials to be treated, and which materials for
the purpose of being more effectively acted upon are placed within a cylinder
or drum, the periphery of which is composed of wire gauze or other suitably
perforated metallic covering. and which cylinder is caused to revolve or rotate
at a suitable speed by means of a handle, drum, or wheel fixed upon a spindle
or axis. The drum is fitted with a door or moveable cover piece, by which the
materials to be treated are placed within the cylinder, and by means of which
the materials after they have been treated may be removed from the cylinder.
The cylinder or drum is mounted within a box or case, the bottom of which is
to be closed by a perforated plate. whilst the top is fitted with a moveable
cover that it may be left wholly or partially open whilst the desiccating
process is being carried on. To the bottom of the box or case is fitted a
funnel-shaped hopper, which acts as a distributing chamber for the hot air, it
being connected at its lower end to the hot-blast pipe in connection with the
furnace or heater, which may be of any suitable construction and placed in
any convenient position for the purpose of heating the air as it is driven through

page_text: or drawn through by means of a fan blast or other suitable contrivance.
By means of throttle valves the admission of air may be regulated to the fan
or other contrivance for forcing or drawing the air through the heater, and
similar valves may be applied to the blast pipe between the heater and
desiccating apparatus for regulating the quantity as well as the temperature of
the air. The quantity of air to be heated and driven through the desiccating
apparatus may also be regulated by a change of the speed of working. The
number of rotations of the cylinder or drum may also be varied during the
progress of the desiccating operation, so as to bring them into correct relation
with the temperature as well as the quantity of air driven through and amongst
the materials under treatment.
In the accompanying Drawing I have shown two modifications of the said
Invention.
Figure 1 is a longitudinal elevation shewing the furnace and air heater in
section Figure 2 is a plan view of Figure 1: Figure 3 is a transverse
sectional view of the cylinder case and apparatus mounted upon wheels, by
which the machine is easily transportable from one place to another: Figure 4
is a vertical section of the furnace and air heater.
In these four views A is the frame or carriage of the machine: B the
wheels C. the axles; D, the framework for supporting the case and cylinder,
in which the process of drying or desiccation is performed; E, the cylinder;
F, the casing for containing the cylinder: G, a hopper beneath the case; H.
hot-air pipe connecting the hopper with the heater: I. the discharge pipe of
the heater: K. the flues for heating the air: L. the admission pipe: M, the
furnace of the heater: N. the chimney: 0. a throttle valve for regulating the
combustion of the fuel: P. a fan or blower: Q. a by-pass pipe for admitting
cold air to the discharge pipe H: R. the framings for supporting the fan and
the shaft S. by which motion may be communicated either by hand or steam
power.
In these Figures the machinery is shewn as being set in motion and operated
by means of bands passing around drums or riggers, the fan being set in
motion and the cylinder containing the leaves to be dried being also rotated
by means of a band or strap.
The air heating apparatus is shewn as being formed of a series of flat cells
or chambers connected the one with the other above the furnace or fire-place,
so that the heat and products of combustion are caused to act directly upon
their surfaces, and are intercepted on their way to the chimney, so that they
may not escape without having efficiently performed the duty required of them.
In Figures 5, 6, 7, and 8, the combination of a steam boiler and an air

page_text: heating apparatus is shewn, having a small steam engine mounted upon the
boiler for the purpose of working the fan blast and rotating the drying cylinder.
In this arrangement or modification of the apparatus according to my In-
vention the steam boiler is shewn as horizontal, having a central flue and
being fired from the side thereof. but a vertical boiler may be employed, and
the steam engine may be placed so as to work vertically. The fan or blower
is shewn as placed at the chimney end of the boiler, and is connected with a
passage or flue so formed as to pass from the one end of the boiler flue
externally along the boiler shell to the furnace end of the boiler fine, where the
air will receive its final heating to the requisite degree before passing through
the discharge pipe into the hopper, and from thence through the distributor
into contact with the contents of the drying cylinder.
By means of the shafts, pulleys, and bands, as shewn in the several Figures.
the necessary amount of air is driven through the heating flue or flues, and
the drying cylinder is caused to revolve at the requisite speed. Instead of
flat band pulleys and straps, cone pulleys for varying the speed may he
substituted. A by-pass pipe is also introduced between the blower and the
hot-air discharge pipe for the purpose of regulating the temperature with
greater accuracy.
In Figures 5, 6, and 8, T is the boiler: U. the furnace: V. the chimney
W, the air-heating flue: X. the cold air by-pass pipe; Y, the steam engine;
Z. the engine shaft. A fly wheel is shewn at one end of the crank shaft,
which is also to be employed for receiving the strap for driving the fan blast,
and at the other end a V-grooved pulley for driving the drying cylinder. The
other portions of these views are similar to those shewn in Figures 1 to 3
inclusive. Like letters of reference denote similar or corresponding parts to
those of Figures 1 to 3 inclusive.
Instead of the horizontal boiler and the horizontal engine mounted thereon.
and the fan blast or blower being placed at the end of the carriage, as shewn in
Figures 5, 6, &c., the engine may be placed on one side of the vertical boiler.
and the fan blast or blower may be bolted to the opposite side of the boiler.
Instead of the outer shell of the boiler being bare or exposed, I prefer, for the
purpose of heating the air. to place a casing around the boiler for the reception
of the air from the blower, so that it may be gradually heated before it is
discharged in contact with the drying cylinder and its contents.
By the
employment of a vertical boiler and the connection of the fan blast at the side
thereof, the carriage and the machine generally may be considerably reduced
in length.
Instead of forming the perforated or wire-covered cylinders as shewn in the

page_text: Drawings, they may be formed in sections, each piece being cast and connected
together around the axis or central shaft. The opening provided for the
admission and removal of the leaves or other contents to be operated upon or
treated may be hinged or otherwise mounted or connected to the cylinder.
The casing or box containing the drying cylinder may have a moveable cover
by which the escape of the air may be regulated.
For the purpose of turning over the leaves or contents of the drying
cylinder more thoroughly, where the nature of the leaf permits of its being
done, the following expedient is employed:-Within the drying cylinder an
open framework may be suspended for the purpose of regulating the motion
of the contents of the cylinder or stirring or agitating the contents, so as more
effectually to bring in contact with every part thereof the heated current of
air; this frame may he suspended from or be mounted upon a spindle, hollow
shaft, or tube made to pass through the axes or hollow trunions of the drying
cylinder.
The carriage (or wheel frame) upon which the machine is mounted is
shewn as being formed of angle and T-irons, although it may be constructed
in any other convenient manner, so as to support the furnace, air heater, and
other parts of the apparatus, and any convenient kind or description of fan or
blower may be substituted for that shewn in the several Figures.
I do not confine myself to the use of woven wire sheets, either employed in
panels or otherwise, as perforated metal plates and other substitutes of a
similar kind may be employed therefor.
The object sought to be effected by the use of this Invention is by means of
the hot-air blast to perform that portion of the tea manufacture known as the
parching and coloring" and "firing or panning processes, at present
performed by means of shallow iron pans placed over a fire.
"
"
The merits of the application of heated air in this operation will be apparent
when it is understood that the air can be applied at any temperature ex-
perience may prove best adapted to develop the virtue of the tea leaf, the
power of the blast, as well as its temperature, being under perfect control.
To the machine may be attached a pyrometer for ascertaining and denoting
the temperature, for regulating which contrivances are provided, as herein
described. The blast or the requisite current of air may be produced by any
of the well-known appliances, such as bellows, fan, or screw, or other well-
known means, placed either at the end of the pipe which supplies the cold air
to the heater, or intermediately between the heater and the cylinder, or in a
position which shall draw the heated air from beyond and through the cylinder.
In every case I prefer to make the drying cylinder uniform and without any

page_text: projecting rib, bar, or break in its inner surface; and the door or opening may
extend the entire length of the cylinder within the Blanches or ends thereof,
instead of as shewn in the Drawing.
The advantages to be derived from the use of the hot-air blast when applied
in the drying of leaves of the tea plant consist in, first, a greater regularity,
and uniformity in parching and coloring the tea leaf by a more equal
distribution of heat; second, that a finer flavor will be obtained owing to the
absence of burnt tea leaf, which occurs in a greater or less degree when
manufactured by the ordinary process; third, that the leaf being subjected to
scarcely any friction by the easy revolution of the internally smooth cylinder
in which it is "parched," will be turned out in a more entire state, and
consequently decrease the quantity of dust and fannings," and by the
rotary action of the cylinder the curling of the leaf is assisted; fourth, that a
considerable reduction in the cost of labour and fuel will be effected, it being
estimated that one of the hand machines constructed according to this Invention
will do the work of six pans, and the fuel and attendance necessary for the same.
What I claim is, first, the use or employment of a current of heated air
in combination with a perforated cylinder or vessel for the purpose of drying
or desiccating the leaves of plants, substantially as herein described.
"
Second, the use or employment of a rotary cylinder formed of wire gauze
or perforated plates in combination with a current of hot air in the manu-
facture for the market of tea from the leaves of the tea plant, as herein
described.
Third, the combination of a rotary cylinder, as herein described, with a fan
or blower and a heater or hot chamber, as herein described and as illustrated
in the accompanying Drawings, for the purpose of drying the leaves of plants
and for other similar purposes.
In witness whereof, I, the said Allan Laurie McGavin, have hereunto
set my hand and seal, this Sixteenth day of February, One thousand
eight hundred and sixty-six.
Witness,
JAMES STEVENSON,
19, Salisbury Street,
Strand.
A. L. M°GAVIN. (L.s.)