A patent is granted by
a national government to protect an invention for a set number of years, usually
20. The first known UK patent was granted to John of Utynam in 1449. The patent
gave John the monopoly on a method of making stained glass which was not known
at that time. It was not until 1718, that a specification was required
before a patent could be granted.
During the Industrial Revolution the number of patent applications increased dramatically.
In 1852 the Patent Law Amendment Act created the Patent Office and
greatly simplified the process of applying for a patent. It also reduced the cost as now
only a single fee was payable, instead of the 7 previously
required.
In 1902 the Patent
Law was again changed, requiring that the Patent Officers verify that a patent
was new and unique by searching through the previous 50 years patents from the
date of application.
George Davidson &
Co only had 12 patents granted to them up until the second world war. The three
most famous are the patent for pearline (No 2641), the patent for the flower
block (No 7830) and the patent for Red Cloud Glass - Ora (No
329022).
All of the English
pressed glass manufacturers were granted patents for various manufacturing
processes. The number, however, was dwarfed by the UK patents granted to US
glass manufacturers, particularly between the two World Wars.
For more information
about patents, visit the Patent Office web site at
www.patent.gov.uk.
When a company or individual applied for a patent, they first
sent in an application which described their invention. The Patent Office issued
them with an application number, the first one each year was always No 1, and
recorded the title and date received in the weekly Patent Journal. The applicant
then had 10 months (7 months before 1918) to submit a complete specification. On
receiving the complete specification a new number was assigned which would
become the patent number if the patent was approved. If the application was not
approved by the Patent Office within 18 months (10 months before 1918), then the
application was lost. Applications for which no complete specification was
received or was not approved were marked as Abandoned by the Patent Office.
The Patent Office only keeps copies of complete specifications,
not of the original application. Thus if an application was abandoned, then only
the title of the application remains.
The table below lists
all of the patents applied for or granted to the Davidson Company. Details of
each patent can be found by clicking on the patent number. No available
specification exists for patents marked abandoned. The patent numbers are not
always sequential which can cause confusion when tracing patents!
Application Number |
Application
Date |
Patent
Number |
Date Approved |
Title |
Comment |
3424 |
25 Aug 1879 |
3424 |
7 Mar 1880 |
Improvements
in the mode of finishing glass tumblers and other like articles |
|
9400 |
25 June 1884 |
|
|
Improvements
in combined hand and steam steering gear |
|
13697 |
16 Oct 1884 |
|
|
Improvements
is steam steering gear and in combined hand and steam steering gear |
This
an the patent above were joint submissions with 'Robert Turnbull a
Mechanical Engineer from Chester-le-Street' |
14030 |
2nd Nov 1886 |
|
|
Improvements in the manufacture of glass
tablets, sheets, slabs and the like for notices and for advertising and
ornamental purposes |
Application
Abandoned |
2641 |
14
Feb 1889 |
2641 |
7 Dec 1889 |
Improvements in the
manufacture of articles of pressed glass |
|
8049 |
14
May 1889 |
8049 |
15
Mar 1890 |
Improvements in pressed
glass dishes and in their manufacture |
|
8531 |
22
May 1889 |
8531 |
29
Mar 1890 |
Improvements in the
manufacture of glass shades for gas burners and such like
|
|
20394 |
13 Dec 1890 |
|
|
Improvements in the manufacture of Pressed Glass Dishes
and the like |
Application
Abandoned |
11906 |
25 Jun 1892 |
|
|
Improvement in the manufacture of glass dishes
and baskets and similar articles of pressed glass. |
Application
Abandoned |
15216 |
7 July 1904 |
|
|
Improvements in the ornamentation of glass |
Application
Abandoned |
12678 |
19 Jun 1905 |
|
|
Improvements relating to the closing of jars
and the like |
Application
Abandoned |
|
19
May 1908 |
10862 |
4 Feb
1909 |
Improvements in the
manufacture of pressed glass
|
|
|
31
Mar 1910 |
7830 |
1 Dec 1910 |
Improvements in the
manufacture of glass flower blocks and the like
|
|
25480 |
15 Nov 1911 |
|
|
Method of stretching pressed glass and
apparatus thereof |
Application
Abandoned |
23460 |
14 Oct 1912 |
|
|
Apparatus for pressing glass |
Application
Abandoned |
12155 |
24 May 1913 |
|
|
Show signs and the like |
Application
Abandoned |
7432 |
23 May 1917 |
|
|
Manufacture
of glass Lens for electric torches etc |
Application
Abandoned |
29300 |
28 Nov 1923 |
|
|
Manufacture
of moulded or pressed glass |
Application
Abandoned |
4575 |
11
Feb 1929 |
329022 |
12 May 1930 |
Manufacture of
coloured glassware |
|
36531 |
28
Nov 1929 |
344032 |
2 March 1931 |
An Improved
flower holder
for use with vases and like receptacles
|
|
1890 |
20
Jan 1931 |
362737 |
10 Dec 1931 |
Improvements in
rose or flower bowls and similar receptacles
|
|
24358 |
29
Aug 1931 |
382699 |
3 Nov 1932 |
Improvements in or
relating to the manufacture of glass flower blocks and the
like
|
|
15013 |
29
Aug 1931 |
382902 |
3 Nov 1932 |
Improvements in or
relating to the manufacture of glass flower blocks and the
like
|
|
8617 |
19
Mar 1935 |
430315 |
17 June 1935 |
Improvements in or
relating to the manufacture of stamped glass
|
|
Patent Number 3424
This was the first Davidson patent and describes a method
of finishing tumblers. The patent explains the method as follows:
"Glass
tumblers and similar articles are inverted over the the shaping block
A, brought up into position by a hinged lever working through an
inverted L slot a in the table B1. A shaping ring C, Figure 5 and 6,
is then passed from the bottom to the top of the tumbler, the lever is
then lowered, and the tumbler is removed by the annular tray b. For
sugar basins and other articles with feet, the apparatus is the same,
with the addition of a vertical rod carrying a sliding horizontal rod
and disc which can be brought over the foot of the sugar basin so as
to keep it in position during the shaping; also the finished basin is
removed by pliers instead of the annular tray."
The patent was issued in the name of George Davidson's son -
John George Davidson. |
Patent Number
2641
This patent describes
the manufacture of 'pearline' glass. In the patent specification Thomas Davidson
says:
“According
to my invention I manufacture articles such as for example as ornamental
dishes, vases, jugs, tumblers, and the like of pressed glass in such a manner
that at the base they are composed of clear glass or glass of any transparent color whilst towards the top they gradually become milky and at their upper
edge opaque.”
Notice how he
spells color the American way! The patent goes onto explain how arsenic, lime
and limespar are added to the normal glass mix and moulded in the normal way.
The glass was allowed to cool for a short while, and then exposed on a
punty or rod to a strong heat. This reheating produced the milky edge to the
piece.
Thomas changed the relative amounts of the different
ingredients
between the provisional specification of February and the completed specification
of December 1889 as can be seen in the
table below ( I have converted from CWTs to pounds):
Ingredient |
February
Specification |
December
Specification |
|
|
|
Sand |
560 lbs |
560 lbs |
Alkali |
224 lbs |
210 lbs |
Nitrate of soda |
28 lbs |
84 lbs |
Phosphate of
lime |
35 lbs |
70 lbs |
Lime spar |
84 lbs |
84 lbs |
Arsenic |
35 lbs |
35
lbs |
Thomas used this specification
to produce Pearline glass in Primrose, Blue and Grey. The technique was
eventually used by other companies.
Patent Number
8049
This patent was
first applied for in May 1889, but it was not until February the following
year that the complete specification was received. The patent describes how to
make a glass dish (Fig 6 right) with a central raised division and with a
loop handle standing on top of the division. This dish is made from a
mould which consists of two or more parts. As Thomas describes the
process:
“According
to this invention I form in pressed glass a hollowed glass dish with a
raised division or partition passing centrally across its interior from
one side to the other and with a loop handle standing up from the top of
this division. This I effect by making the body of the mould by which
the inside of the dish and the handle are shaped in two or more sections
meeting together in a plane passing through the longitudinal central
line of the handle. Whilst a dish is being moulded the sections are held
together at the top by a ring embracing them and the plunger which
moulds the greater part of the underside of the dish descends through
the ring”
Prior to this invention,
the handles for a dish had to be applied manually, which made them more
expensive to make. The technique described in this patent means that the
dish can be made in a single action, thus reducing the
cost.
|
Patent Number
8531
This patent describes how
lighter and thinner glass gas burner shades can be made by first making a
cylinder with a dome end in pressed glass and then expanding out the domed
end and moulding it to the form required. Thomas describes the process as
follows:
“To
form a shade I first make in pressed glass a short cylinder with dome end and
with a hole of comparatively small diameter through the centre of the dome.
When taken from the mould the dome end whilst kept in a soft state by the
application of heat is rotated so as to cause it to open out and expand until
the hole in the centre of the dome is enlarged to a diameter greater than the
opposite end of the form - whilst the enlarged end is still soft it is placed
vertically on to a shape which supports it at various points around its
circumference and leaves it unsupported at others so allowing these parts to
droop inwards.”
The effect of
supporting the shade in this way is to form flutes around the edge of the shade.
The provisional specification was submitted in May 1889, and the complete
specification in February 1890.
Patent Number
10862
This patent describes a
method of producing thinner pressed glass with an improved surface. The
provisional specification was dated 19th May 1908 and the complete
specification was accepted on 4th February 1909.
In this patent
Thomas Davidson describes a mould with the top left open. Excess glass is
allowed to escape from the top where it can be easily trimmed off. With a
closed mould the excess glass has no where to go and so results in a
thicker moulding. In Thomas' design the plunger is shaped so that it thins
or indents the glass around the edge of the mould and thus makes it easier
to trim off. In the diagram on the left, the plunger is marked c. The top
of the plunger c' allows for the excess glass to escape and thin. In
pressing the glass Thomas suggests that the plunger be brought down
quickly (say 5 times) and withdrawn - the operation being more of a
stamping than of a slow pressing nature. By doing this the glass in the
mould is not cooled so quickly and the surface of the resulting piece is
improved.
|
Patent Number
7830
This is probably Thomas
Davidson's most famous patent after the pearline patent. It describes a
method for producing the flower block which is so familiar to all Davidson
collectors. Note, Thomas did not patent the idea of a flower block, but
patented a method of producing one. The provisional specification was
drawn up in March 1910 and the complete specification was submitted in
September 1910. The making of a flower block is a two stage
process:
“According
to this invention sufficient molten glass to form the article is placed
in the usual way in a mould of the shape of the bottom and sides of the
block and a plunger is inserted into the glass to form the holes. The
mould with the glass in it is then turned upside down onto another mould
of the shape required for the finished upper part of the article. The
glass which is to form the top of the article being still hot sags or
droops into this second mould whilst the glass of the bottom and sides
which has been in contact with the first mould having becomes cooler and
more rigid retains its shape”
The shapes of the two moulds can be seen in the diagram on
the right. This technique allows for the flower block to have
a more complicated and pleasing shape. It also allows for larger flower
blocks to be made. Davidson continued to make flower blocks
using this patent up until the 1960s. Two subsequent patents in 1931 improved
the manufacture of flower blocks, however the basic shape remained
unchanged. |
Patent Number
329,022
This is perhaps the most
unlikely patent that was ever accepted in the 20th century. Thomas has patented
the technique of painting glass! The patent was produced to protect Red Cloud
glass (known as Ora). In the patent Thomas says:
“A
variety of pleasing and unusual effects due to the diffusion of a dominating
coloured light through translucent glass with cloud or variegated effects can
readily be produced in accordance with the invention”
Thomas describes the technique as:
“According
to the invention, the glass is produced with mixed, cloud or streak effects by
an appropriate interfusion or mingling of two or more shades, and the article
into which the said glass is shaped is coated with a backing of coloured
paint or enamel For instance, a flower bowl is constructed of glass with cloud
effects produced, for example, by blending in streaks or patches a limited
proportion of purple or other dark coloured glass into a mass of light amber
glass, and the underside of the bowl is coated by painting or spraying with a
paint or enamel of any desired colour. The surface colouring may be effected
with a vitreous or enamel colouring which is burnt on by spraying or painting
with pigmented or dyed cellulose solutions or with ordinary oild and varnise
paints”
The only known use of this technique was Red Cloud, which was Purple
Cloud Glass painted on the underside or inside with a red paint. The lack of
durability of the paint meant that Red Cloud was not a financial
success.
The provisional specification was submitted on 11th February
1929 and the complete specification on 29th October 1929. The patent was not
accepted until May of 1930.
Patent Number 344032
The simple patent took over a year to be
granted. The provisional specification was submitted on the 27th November
1929 and the complete specification on the 11th August 1930. The patent
was finally granted in March 1931.
Thomas describes a simple holder for flowers in vases
and like articles. The holder, which could be of glass or any other
material, is wheel shaped and sits inside the top of the vase, being
supported by the walls of the vase.
|
Patent Number 362737
This patent was not taken
out by Thomas Davidson but by one 'Frederic Atkinson of 49 Queen Victoria
Street London EC 4, a British Subject'. However Davidson did produce a number of flower bowls
which used this design. Normally the flower block or frog rests in the base of
the flower bowl. In this design the flower block has three lugs on the outer
edge which mate with notches moulded into the base of the flower bowl. From
personal experience the problem with the design is that the frog sits too
tightly in the flower bowl and can be very difficult to remove!
The two images below show the patent in action. On the right is a
standard 4" frog with the three lugs visible. On the left you can see how the
frog sits recessed into the bottom of the flower bowl.

It is not known who Mr Atkinson was or what his relationship
was with Davidson.This design was first mentioned in the 1935 Pottery
Gazette.
Patent Number 382699
This
patent contains two improvements to the 1910 patent No 7830. The
provisional specification was submitted on 29th August 1931 and the
complete specification was submitted on 26th May 1932. This is quite a long and
complicated patent but essentially it describes a method which makes it easier
to pierce the holes in the base of the frog during manufacture.
In the original patent, the fingers which formed the holes in the flower
block did not extend to the base of the mould. This meant that there was quite a
thickness of glass which had to be manually pierced to complete the holes in the
flower block. This patent describes a mould which has a series of small
projections in the base of the mould which align with the fingers from the top
part of the mould. When the frog is made, the glass at the base of the holes
is thin and so is easier to pierce.
The patent also describes some other improvements to the mould. These
include a spigot-like portion which allows for excess glass to escape when the
plunger is lowered and mounting the fingers, which make the holes, separate from
the main plunger to avoid excess wear and to allow for movement at different
temperatures.
Frogs made after the introduction of this patent bear this patent number
and that of patent No 382902.
Patent Number 382902
This patent, which was divided out from No 382699 describes improvements
to the second part of the manufacture of the flower block. In patent 7830 it is
described how the top part of the flower block is made by inverting the part
formed flower block and allowing the molten glass to droop into a second mould
to form the top half of the block. This patent describes two methods whereby
compressed air is used to help shape the top part of the brick. The first method
has the second mould perforated to allow compressed air into the mould and help
form the top part of the holes. The second method does away with the second
mould altogether and uses compressed air to shape the top surface of the flower
brick.
Patent Number
430315
This was the final
patent which Thomas Davidson produced and was submitted in June 1935. The
patent describes an improvement to his 1908 patent (10862) for making
pressed glass with thinner sides. The plunger now has a sharp edge which
when the plunger is inserted into the open mould almost comes into contact
with a similar sharp edge of the mould. This has the effect of pinching
the excess glass and making it easier to cut when the piece is finished.
See diagram left.
|
|