AN IMPROVED AIRTIGHT AGITABLE LAMP
Year: 1809

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
GRIFFITH, of Birmingham, in the County of Warwick, Optician, do send
greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Ninth day of November, in the fiftieth year of His reign, did
give and grant unto me, the said Edward Griffith, His especial licence that
I, the said Edward Griffith, my executors, administrators, and assigns, during
the term of years therein expressed, should and lawfully might make, use,
exercise, and vend, within England, Wales, and the Town of Berwick-upon-
Tweed, my Invention of "AN IMPROVED AIRTIGHT AGITABLE LAMP;" in which
Letters Patent there is contained a proviso obliging me, the said Edward
Griffith, by an instrument in writing under my hand and seal, to cause a
particular description of the nature of my said Invention, and in what manner
the same is to be performed, to be inrolled in His Majesty's High Court of
Chancery within two calendar months next and immediately after the date of
the said recited Letters Patent, as in and, by the same, relation being thereunto
had, may more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Edward Griffith, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, is described in the Drawings
in the margin of these Presents, and the following description thereof, that is
to say:-
The principle on which my Improved Airtight Agitable Lamp acts, is by means

page_text: of a spring or springs which I put into a tube or vessel, made of tin, brass,
copper, silver, or any other metal or mixed metals, or various other materials, and
of any size and shape I think proper, which I call the oil tube.
On the upper
end of the spring or springs I place a bucket or cup made of the same metal
or materials, and form of the oil tube or vessel, or of such materials and form
I think proper. When this bucket or cup is required to be filled with oil or
spirits, which is put into the tube, I press it down by means of a wire pin
through the air hole in the top of the tube. The bucket or cup being filled,
and the wire pin withdrawn, the spring raises the bucket or cup so filled to
the top of the lamp, which immerses the wick or wicks, and renders the light
clear and regular. The wire pin I make of steel wire, with a brass thumb
piece on the top, but it may be made of any other metals which will answer
the purpose.
Figure 1 is a section of the lamp with a cylindrical tube, with its spring
bucket, wire pin, small tube for holding the wire pin and top, and burner
or wick tube, drawn full size of one of the sized lamps I make; but be
it remembered, I make them of any length and diameter, or oval, square,
oblong square, or other shape I think proper. A, the oil tube or vessel, with
a bottom or foot fastened to it by solder, or in any other way I think proper; or
I make them without a bottom or foot, with a spigot end, to stick in a bracket
candlestick lanthorn, or for any other purpose they can be applied to; or I make
them with two tubes, to slide in the same manner as a telescope, to raise and
fall the light when required. B, the spring, which I make of steel or other
metal, or metalline or elastic substance, of diameter or other form and length
to suit the oil tube or vessel. I have adopted a spiral spring, but it may be
made in any other form that will answer the purpose to raise the oil when
required. C, a double cup or bucket, consisting of two tubes and a ring,
soldered or otherwise made fast in the larger, and a bottom in the smaller;
the larger is a little less than the oil tube, in order to let the oil or spirits
with which the tube or vessel is filled to pass between the bucket or cup,
and tube or vessel, when it is pressed down by the wire pin, to be filled, the
lesser tube about one quarter of an inch less than the greater, which receives
the burner or wick tube or tubes, and wick or wicks. It is perforated with
holes above the ring or bottom of the greater tube to let the oil, &c. out of
the interstice to the wick or wicks. The interstice is to receive the end of
the wire pin through the air hole in the top of the lamp, to prevent the
wick or wicks from being carried down with the bucket or cup; the wide part
of the bucket or cup rests upon the top of the spring, and the narrow part
goes within it. I also make the bucket or cup in various other forms, as I