CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF PLATE GLASS
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
CROSFIELD, of Warrington, in the County of Lancaster, Soap Manufacturer,
send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-fifth day of March, in the third year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said Joseph
Crosfield, Her especial licence, full power, sole privilege and authority, that I,
the said Joseph Crosfield, my executors, administrators, and assigns, should
agree with, and no other, from time to time and at all times during the term
of years therein expressed, should and lawfully might make, use, exercise, and
vend, within England and Wales and the Town of Berwick-upon-Tweed, my
Invention of "CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF PLATE GLASS;"
in which Letters Patent is contained a proviso that I, the said Joseph
Crosfield, shall cause a particular description of the nature of my said Inven-
tion, and in what manner the same is to be performed, to be inrolled in Her
Majesty's High Court of Chancery within six calendar months next and
immediately after the date of the said in part recited Letters Patent, as in and
by the same, reference being thereunto had, will more fully and at large
appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Joseph Crosfield, do hereby declare that the nature of my said Invention, and

page_text: the manner in which the same is to be performed, is particularly described
and ascertained, in and by the Drawings hereto annexed, and the following
explanation thereof (that is to say):-
My Improvements in the Manufacture of Plate Glass consist,―
Firstly, with reference to fluxing the raw materials or cullet, in a more
economical application of fuel, for the purpose of fluxing the raw materials or
cullet of which it is composed, and which is effected by performing such
operation in a reverbatory furnace, or in a furnace similar to those used for
smelting of copper or other metallic ores, or for re-melting cast iron. The
glass, as it is fluxed, is then made to flow into a clay pot, such as is commonly
used for fluxing glass in. This pot may be either covered or opened. By
this mode of fluxing the materials or cullet I effect a considerable saving both
in the quantity of fuel and the cost of pots. The reverbatory furnaces may be
used in connexion with the glass-house furnaces now ordinarily used, or, as is
hereafter more particularly described, may be constructed so as to have a
separate furnace for each pot. And this method of fluxing the materials may
be applied either to a fixed melting pot, and the glass, after being melted, be
laded out into a refining pot, or the pot may be a moveable one and the metal
be brought fine in it, without refining in a second pot or cistern.
Secondly, with reference to those machines which are commonly employed
for grinding plate glass, my improvements consist in placing four grinding
benches or stones at right angles from each other; the runners or upper frames
of which are all put into motion at the same time by one crank moving the
fly frame, instead of having two grinding benches or stones placed opposite to
each other, as has hitherto been the practice. By this improvement a great
saving of power is effected, and a considerable saving in the cost of the
machinery. I also make the bottom or bed stone move upon a railway, by
placing it upon wheels, by which means I can move it backwards and for-
wards, either by manual labor or by mechanical means, and thus avoid the
changing of the position of the top frame or runner when grinding glasses of
a large size.
Thirdly, with reference to those machines which are commonly employed for
polishing plate glass, my improvements consist in adding one, two, or more
additional polishing bars to the number hitherto used on each polishing bench
or frame, but I give the preference to four, rather than more or less, as
hereafter more particularly described. The advantages hereby gained are the
finishing a larger quantity of glass in the same time than can be done with
the same number of polishing benches, having only two polishing bars, thereby
saving both power and also bringing the glass to a better polish. The

page_text: runners e, e, e, e, being actuated by cranks and connecting links f, f, which will
also be well understood by persons conversant with such machinery.
Having now particularly described my improvements in the manufacture
of plate glass, and the manner in which the same are to be performed, I
desire it to be understood that I claim as my Invention,―
Firstly, the fluxing of the raw materials or cullet in a reverbatory furnace,
in the first instance, by the direct application of the heat upon them without
the intervention of a pot or vessel, in which the materials are fluxed without
being in any way confined in its application to the particular form of furnace
shewn in the Drawing.
Secondly, placing four grinding benches with their runners all put in motion
with their fly frame by one driving crank in the grinding machine.
Thirdly, having additional polishing bars (I prefer four in all) as above
described with reference to the polishing machine.
In witness whereof, I, the said Joseph Crosfield, have hereunto set my
hand and seal; this Twenty-third day of September, in the year of our
Lord One thousand eight hundred and forty.