IMPROVEMENTS IN CAST-IRON PIT TUBBING
Year: 1863

page_text: Sealed the 17th December 1864, and dated the 7th October 1863.
PROVISIONAL SPECIFICATION left by the said John Gibson at the
Office of the Commissioners of Patents, with his Petition, on the 7th
October 1863.
I, JOHN GIBSON, of Ryhope Colliery, Sunderland, Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN CAST-IRON PIT
TUBBING," to be as follows:-
My Invention has for its object the protection of the cast iron used in pit
tubbing from the rapid and destructive corrosion to which it is liable when
cast in the ordinary manner, and consists in the application of the process of
chilling" to this purpose.
Instead of casting the iron in sand as usual, it is cast in iron moulds com-
monly called "chills," the effect of which is to cool the surface of the casting
rapidly, and thereby cause the outer portion of the casting to become closer

page_text: in grain to the depth required, so as to render the metal Tore capable or
resisting corrosion.
Tubbing composed of cast iron thus manufactured when used in the shafts
of collieries and mines will be protected from the usual tendency to rapid
corrosion arising from the combined action of smoke and moisture.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Gibson in the Great Seal Patent Office on the 7th
April 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
GIBSON, of Ryhope Colliery, Sunderland, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of October, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-seventh year of.
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Gibson, Her special license that I, the said John
Gibson, my executors, administrators, and assigns, or such others as I, the
said John Gibson, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
ánd Ireland, the Channel Islands, and Isle of Man, an Invention for "Iμ-
PROVEMENTS IN CAST-IRON PIT TUBBING," upon the condition (amongst others)
that I, the said John Gibson, by an instrument in writing under my hand and
seal, 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 John Gibson, 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,
reference being bad to the Drawings hereunto annexed, and to the letters and
figures marked thereon (that is to say) :—
My, Invention of "Improvements in Cast-iron Pit Tubbing," has for its.

page_text: object the protection of the cast iron used in pit tubbing from the rapid and
destructive corrosion to which it is liable when cast in the ordinary manner,
and consists in the application of the process.of "chilling" to this purpose.
Instead of casting the iron in sand as usual, it is cast in iron moulds com-
monly called "chills," the effect of which is to cool the surface of the casting
rapidly, and thereby cause the outer portion of the casting to become closer
in grain to the depth required, so as to render the metal more capable of
resisting corrosion.
Tubbing composed of cast iron thus manufactured when used in the shafts
of collieries and mines will be protected from the usual tendency to rapid
corrosion arising from the combined action of smoke and moisture.
Having thus stated the nature of the said Invention, I would remark that
the process of "chilling" cast iron is well known in its application to the
casting of iron for various purposes wherein hardness of surface is required,
but my Invention in distinction from the ordinary mode of casting iron for pit
tubbing, consists in producing by means of the process of chilling, a cast iron
for the purpose, with a surface or outer portion rendered closer in grain, to
the depth inwards of three-eighths of an inch or thereabouts, such closely
grained surface being thus capable of resisting the ordinary tendency to cor-
rosion in pit tubbing. My Invention, however, is not confined to such
particular depth of chilled or condensed closely grained surface, the depth of
chill depending upon the thickness and strength of metal behind it.
The ordinary process of "chilling " being well known, it is not necessary to
describe it here further than to state that for this particular purpose of casting
iron for pit tubbing, I use a metal chill plate combined with an ordinary metal
box and sides for sand casting, the face alone of the tubbing receiving the
chill to the depth required, and the sides and back being cast in sand as usual.
In the accompanying Drawing Fig. 1 is a longitudinal section through the
boxes, and Fig. 2 is a plan or horizontal view shewing the top box removed.
A is the ordinary top box; B, the sides cramped to the metal chill plate C.
A segment of cast-iron pit tubbing is shewn at D. It will be seen that by
this arrangement the face of the segment D will be chilled to the required
depth according to the quality of the metal used, (as indicated by the black
line in Fig. 1,) the remainder of the casting being formed as usual.
Having thus described the nature of the said Invention, and in what manner
the same is to be performed, I hereby declare that I do not claim as of my
Invention the process of "chilling" cast iron except as applied to casting iron

page_text: for pit tubbing; but what I do claim as of my Invention, is the casting of iron
for pit tubbing by means of the process of "chilling," in order to prevent cor-
rosion, as herein-before described.
In witness whereof, I, the said John Gibson, have hereunto set my
hand and seal, the Fifth day of April, in the year of our Lord
One thousand eight hundred and sixty-four.
Witness,
WILLIAM Spence,
50, Chancery Lane,
Patent Agent.
JOHN GIBSON. (L.S.)