IMPROVEMENTS IN APPARATUS FOR CUTTING STONE
Year: 1877

page_text: LETTERS PATENT to John Dickinson Brunton, of Leighton Crescent, Kentish
Town, in the County of Middlesex, for the Invention of "IMPROVEMENTS IN
APPARATUS FOR CUTTING STONE."
Sealed the 14th May 1878, and dated the 4th December 1877.
PROVISIONAL SPECIFICATION left by the said John Dickinson Brunton at
the Office of the Commissioners of Patents on the 4th December 1877.
JOHN DICKINSON BRUNTON, of Leighton Crescent, Kentish Town, in the County
of Middlesex. IMPROVEMENTS IN APPARATUS FOR CUTTING STONE."
My Invention relates to apparatus which is especially adapted for use in the
excavation of tunnels by what is known as Brunton's tunnelling machine, but is
also applicable to the formation of rebates or internal angles in stone; and it con-
sists in the employment of rotating circular cutters of two descriptions mounted on
one and the same revolving chuck, one of which is an arroding cutter, having, say,
three V edges formed on its circumference for the purpose of arroding or crumbling
away one face of the rock or stone, so as to free the internal angle formed at the
point of intersection therewith of the other face for the more ready operation of the
second cutter, whilst the said second cutter is constructed with a chipping-off edge
adapted to operate in the angle of the two faces and the face secondly mentioned,
and with, say, two arroding V edges, so as to act upon the face first mentioned
between the channels or grooves made by the V edges of the first cutter. When
applied to tunnelling operations the first cutter acts upon the cylindrical internal
face of the tunnel, and the second cutter splits fragments or chips off the face of the
rock at the end of the tunnel, whilst the arroding edges on the second cutter
supplement the action of those on the first cutter.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Dickinson Brunton in the Great Seal Patent Office on the 31st
May 1878.
JOHN DICKINSON BRUNTON, of Leighton Crescent, Kentish Town, in the County
of Middlesex. "IMPROVEMENTS IN APPARATUS FOR CUTTING STONE."
My said Invention relates to apparatus which is especially adapted for use in the
excavation of tunnels by what is known as Brunton's tunnelling machine, but is
also applicable to the formation of rebates or internal angles in stone; and it
consists in the employment of rotating circular cutters of two descriptions mounted
on one and the same revolving chuck, one of which is an arroding cutter, having,
say, three V edges formed on its circumference, for the purpose of arroding or
crumbling away one face of the rock or other stone, so as to free the internal angle
formed at the point of intersection therewith of the other face for the more ready
operation of the second cutter, whilst the said second cutter is constructed with a
chipping-off edge, adapted to operate in the angle of the two faces and upon the
face secondly mentioned, and with, say, two arroding V edges, so arranged as to act
upon the face first mentioned between the channels or grooves made by the V edges
of the first cutter When applied to tunnelling operations the first cutter acts upon
the cylindrical internal face of the tunnel, and the second cutter splits fragments or
chips off the face of the rock at the end of the tunnel, whilst the arroding edges on
the second cutter supplement the action of those on the first cutter.
The accompanying Drawing illustrates a mode of carrying out my said
Invention.
Figures 1 and 2 of the Drawing are respectively a front and side elevation of a
chuck carrying the improved cutters; and Figures 3, 4, and 5 are sectional
diagrams illustrating the construction and operation of the cutters.
A is a revolving chuck, on which are mounted (so as to receive a positive
independent rotary motion on their own axes) three circular cutters B, C, C, one of
which, videlicet, that marked B, is of the form shewn in Figure 3, whilst the other
two (videlicet, C, C,) are of the form shewn in Figure 4.
The cutter B is a purely arroding cutter, having V edges a, b, c, formed in its
circumference, the action of which is to arrode or crumble away the face 1, 2, and
thus free the internal angle formed by the two faces 1, 2-2, 3, for the more easy
operation at that point of the splitting-off edge d of the cutters C, C.
The cutters C, C, are each formed with a chipping-off edge d, before referred to,
suited to chip off the face 2-3, and with arroding V edges e, f, so placed as to act
on the face 1, 2, between the channels or grooves previously made by the V edges
b, c, of the cutter B.
The diagrams, Figures 3 and 4, shew respectively the action of the cutter B, and
one of the cutters O separately; and the diagram Figure 5 indicates in black lines
the action of the cutter B at a given point, and in dotted lines the action of a
cutter C, when by the revolution of the chuck A it comes into the position which
the cutter B is assumed now to occupy. This combination is especially useful in
the excavation of tunnels by my patent tunnelling machine. The cutter B
acting on the cylindrical internal face of the tunnel, and the cutters C, C, splitting
fragments or chips off the face of the rock at the end of the tunnel, whilst the
arroding edges on the cutters C, C, supplement the action of those on the
cutter B.
The combination is also applicable to the formation of rebates or internal angles
in stone.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein-before in part

page_text: recited Letters Patent is, the employment in combination of cutters constructed
and arranged so as to operate substantially in the manner and for the purposes
herein-before described.
In witness whereof, I, the said John Dickinson Brunton, have to this my
Specification set my hand and seal, the Twenty-fifth day of May, One
thousand eight hundred and seventy-eight.
JOHN DICKINSON BRUNTON. (L.S.)