IMPROVEMENTS IN THE CONSTRUCTION OF SAWS
Year: 1873

page_text: LETTERS PATENT to Robert Fawcett Thompson, of Barnard Castle, in
the County of Durham, for the Invention of “IMPROVEMENTS IN
THE CONSTRUCTION OF SAWS."
Sealed the 5th June 1874, and dated the 9th December 1873.
PROVISIONAL SPECIFICATION left by the said Robert Fawcett
Thompson at the Office of the Commissioners of Patents, with his
Petition, on the 9th December 1873.
I, ROBERT FAWCETT THOMPSON, of Barnard Castle, in the County of
Durham, do hereby declare the nature of the said Invention for
“IMPROVEMENTS IN THE CONSTRUCTION OF Saws," to be as follows:-
This Invention relates to saws used for the purpose of cutting stone
or other hard substances, and has for its object improved methods of
constructing and arranging the cutting edges or teeth of such saws, by
which methods the teeth are more durable and cut with greater rapidity
than in saws as ordinarily constructed and used.
My Invention consists of novel methods of fixing and arranging
fragments of diamond or other sufficiently hard gems upon the cutting

page_text: edges of saws, and it is applicable both to circular saws mounted upon
suitable centres and caused to revolve with sufficient speed in the
method ordinarily used and practised, and to reciprocating saws having
a cutting edge, either straight or curved, and caused to reciprocate
backward and forward in contact with the stone or other hard substance
to be cut by hand, steam, or other convenient power.
.
In order to carry my Invention into operation (where a circular
revolving saw is to be used) I take a circular disc of any suitable material,
but preferably of steel, properly mounted upon a central axis fitted in
bearings so that it can be made to revolve as above described. I make
this disc of such thickness at its edge that one or more holes may be
drilled or cut in its periphery, into each of which holes I fit and fix a
fragment of diamond or other hard gem. Each such fragment is fixed
into the hole in which it is fitted either by cement or by carefully fitting,
hammering, or adjusting round it the edges of the hole, a sufficient portion
only of the diamond or gem being left projecting from the hole for the
purpose of cutting the stone or other hard substance. The back of each
hole (relative to the direction in which the saw is revolving) may
be made higher than its front so as to afford greater support to the
diamond or other gem.
Sometimes I arrange the holes in which the diamonds or gems are
fitted nearer to one or other side of the saw alternately (instead of in a
line round the centre of the edge), so as to facilitate the "clearance"
of the saw as it passes through the stone or other hard substance; and
sometimes for the same purpose I fit fragments of diamond or other gems
into holes formed in the periphery of the saw at the sides as well as its
edge; and in such case I prefer to arrange the several holes in which
the fragments are fitted alternately instead of opposite to or near to
each other. Sometimes I make the edge of the disc which forms the saw
of greater thickness than its central portion, so that more space is
available in which to form the holes for the fragments of diamond or
other gems.
Where reciprocating saws are used constructed according to my.
Invention, I adopt similar methods for the purpose of fixing and
arranging the fragments of diamond or other gems; but I arrange such
fragments at one edge only, or at such edge and its adjacent sides of
the plate which forms the saw.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Fawcett Thompson in the Great Seal
Patent Office on the 9th June 1874..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
FAWCETT THOMPSON, of Barnard Castle, in the County of Durham,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of December, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Robert Fawcett Thompson, Her
special licence that I, the said Robert Fawcett Thompson, executors,
administrators, and assigns, or such others as I, the said Robert
Fawcett Thompson, my executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF SAWS," upon the
condition (amongst others) that I, the said Robert Fawcett Thompson,
my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, 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 imme-
diately after the date of the said Letters Patent..
NOW KNOW YE, that I, the said Robert Fawcett Thompson, 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 (that is to say):-
My Invention relates to saws used for the purpose of cutting stone or
other hard substances, and has for its objects improved, methods of
constructing and arranging the cutting edges or teeth of such saws ;.
by which improved methods the teeth are more durable, do not require
sharpening, and 'cut with greater rapidity than in such saws as ordinarily
constructed and used.

page_text: In order to carry my Invention into operation I use novel methods of
fixing and arranging fragments of diamond or other sufficiently hard
gems or flinty stone upon the cutting edges of saws, which methods are
applicable both to circular saws mounted upon suitable centres and
made to revolve with sufficient speed by means of belts and pullies or
other gear, in the method ordinarily used and practised, and also to
reciprocating saws having a cutting edge, either straight or curved, and
caused to reciprocate backward and forward in contact with the stone or
other hard substance which is to be cut by means of hand, steam, or
other convenient power.
Where a circular revolving saw of the kind described, working vertically
or horizontally, is to be used, I take a circular disc of any sufficiently rigid
material, but preferably of steel, and I mount it in the usual way upon a
central axis fitted in bearings so that it can be made to revolve as above
described, and I make the disc of such thickness at its edge that one or
more holes may be drilled or cut in its periphery, into each of which holes
I fit and fix a fragmont of diamond or other hard gem or hard flint stone.
I fix each such fragment into the hole in which it is fitted by means of
cement, or by carefully fitting, hammering, or adjusting round it the
edges of the hole, a sufficient portion only of the fragment of diamond,
gem, or flint, being left projecting from the hole in order to cut the
stone or other hard substance during the revolution of the disc. The
back of each hole (relatively to the direction in which the disc revolves)
may be made higher than its front, so as to afford greater support to the
diamond or other gem or flint.
I arrange the fragments of diamond or other gem or flint so that their
cutting edges project beyond the edge and sides of the disc, in order
that there may be sufficient clearence for the latter to revolve without
touching the stone or other substance which is being cut; and some-
times I arrange the holes in which the fragments are fitted as described
nearer to one or other side of the disc alternately instead of in a line
round the centre of the periphery of the latter, so that a wider cut is
made in the stone or other substance and the "clearance" of the disc
is facilitated. And sometimes for the same purpose I fit and fix
similar fragments of diamond or other hard gem or flint into holes
formed in the sides of the disc at or near its periphery, as well as at its
edge, and in such case I prefer to arrange the holes into which the
several fragments are fitted in positions alternating with each other

page_text: instead of opposite or near each other; and sometimes I make the edge
of the disc of greater thickness than the remainder, so that more space
is available in which to form the holes to receive the fragments of
diamond or other gems..
Where reciprocating saws constructed and arranged according to my
Invention are to be used, working vertically or horizontally, I adopt
similar methods of arranging and fixing the fragments of diamond
or other gems or flints, but I arrange such fragments at one edge
only, or at such edge and its adjacent sides of the plate which forms
the saw.
Instead of fixing the fragments of diamond, gem, or flint to the edge
of the saws as described, I sometimes fix them in the method described
to separate blocks or pieces of metal, which are dovetailed into or other-
wise attached to the edge of the saw, so that they can be readily
removed or replaced as desired.
Having now described my Invention and the manner in which it is
to be performed, I claim, the methods of arranging and fixing fragments
of diamond or other gems or stones upon the edges of saws, substantially
as and for the purpose described.
In witness whereof, I, the said Robert Fawcett Thompson, have
hereunto set my hand and seal, this Eighth day of June, in
the year of our Lord One thousand eight hundred and seventy-
four.
ROBERT FAWCETT THOMPSON. (L.S.)