IMPROVEMENTS IN THE MANUFACTURE OF PISTON PACKING FORMED OF CANVAS, CLOTH, OR OTHER TEXTILE MATERIAL IN COMBINATION WITH INDIA-RUBBER OR INDIA-RUBBER COMPOUNDS SUSCEPTIBLE OF VULCANIZATION." PROVISIONAL SPATION
Year: 1871

page_text: LETTERS PATENT to Isaac Blue Harris, of Castle Mills, Fountain-
bridge, Edinburgh, Rubber Works Superintendent, for the Inven-
tion of "IMPROVEMENTS IN THE MANUFACTURE OF PISTON PACKING FORMED
OF CANVAS, CLOTH, OR OTHER TEXTILE MATERIAL IN COMBINATION WITH
INDIA-RUBBER OR INDIA-RUBBER COMPOUNDS SUSCEPTIBLE OF VULCANIZATION."
PROVISIONAL SPECIFICATION left by the said Isaac Blue Harris
at the Office of the Commissioners of Patents, with bis Petition,
on the 24th October 1871.
I, ISAAO BLUE HARRIS, of Castle Mills, Fountain Bridge, Edinburgh,
5 Rubber Works Superintendent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF PISTON PACKING FORMED'
OF CANVAS, CLOTH, OR OTHER TEXTILE MATERIAL IN COMBINATION WITH INDIA-

page_text: RUBBER OR INDIA-RUBBER COMPOUNDS SUSCEPTIBLE OF VULCANIZATION," to be as
follows:-
Piston packing formed from canvas coated with india-rubber or india-
rubber compounds has hitherto been manufactured by rolling strips of
such coated canvas into straight flexible cords or ropes, either round or
square. Some of these cords or ropes have a central strand or core of
india-rubber or india-rubber compounds and have been called coro
packing; others again have no core and have been called rope or cord
packing. Both forms have been made as already stated into straight
flexible cords or ropes of varying lengths, and sometimes vulcanized in
that form. From these straight lengths pieces are cut off of varying
lengths as required, and bent round to form "open rings" to embrace the
piston rod or other piece intended to move steam, air, or fluid-tight
through them, as in common use in glands or stuffing boxes. This
mode of fitting in or applying the packing is very troublesome, and the
packing is often put in unequally tight and afterwards unequally
crushed, while the ends of the rings often fit badly, and no provision
whatever is made for equalizing the pressure on and lubrication of the

page_text: box presses this corc into a circular one, thus communicating tightness
round the rod and stuffing box, and with more regularity than herc-.
tofore.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Isaac Blue Harris in the Great Seal Patent Office
on the 20th April 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ISAAC
BLUE HARRIS, of Castle Mills, Fountain Bridge, Edinburgh, Rubber
Works Superintendent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of October, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Isaac Blue Harris, Her special
licence that I, the said Isaac Blue Harris, my executors, adminis-
trators, and assigns, or such others as I, the said Isaac Blue Harris,
my exccutors, 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 MANUFACTURE OF PISTON PACKING FORMED OP
CANVAS, CLOTH, OR OTHER TEXTILE MATERIAL IN COMBINATION WITH INDIA-
RUBBER OR INDIA-RUBBER COMPOUNDS SUSCEPTIBLE OF VULCANIZATION," upon the
condition (amongst others) that I, the said Isaac Blue Harris, 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 immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Isaac Blue Harris, do hereby
declare the nature of my said Invention, and in what, manner the

page_text: same is to be performed, to be particularly described and ascertained in
and by the following statement, reference being had to the Drawing
hereunto annexed (that is to say) :-
Piston packing formed from canvas coated with india-rubber or
india-rubber compounds has hitherto been manufactured by rolling
strips of such coated canvas into straight flexible cords or ropes, either
round or square. Some of these cords or ropes have a central strand or
core of india-rubber or india-rubber compounds, and have been called
core packing; others again have no core and have been called rope or
cord packing.
Both forms have been made as already stated into
straight flexible cords or ropes of varying lengths, and sometimes
vulcanized in that form. From these straight lengths pieces are cut off
of varying lengths as required, and bent round to form "open rings" to
embrace the piston rod or other piece intended to move steam, air, or
fluid tight through them, as in common use in glands or stuffing boxes.
This mode of fitting in or applying the packing is very troublesome, and
the packing is often put in unequally tight, and it is afterwards
unequally crushed, while the ends of the rings often fit badly, and no
provision whatever is made for equalizing the pressure on and lubrication
of the rod that works through the packing.
To avoid these inconveniences is the object of my present Invention,
which consists in coiling the lengths of piston packing (prepared as
heretofore, and while in a soft uncured or unvulcanized state) upon
mandrils, each into a spiral (like bell-pull springs) and submitting them
while retained in that form by bands or otherwise, to vulcanization.
The effect of this operation on the packing will be to give the lengths a
permanent spiral or helical "set.” The advantages of this form for a
piston packing are important, for a piece of several convolutions can be
cut off and expanded into fewer convolutions or into a single ring, or a
single convolution may be contracted into a greater number of convolu-
tions always retaining the circular form, and thus the packing will.
always be ready not only to be formed into rings to fit piston rods of
various sizes more perfectly but with more smoothness and regularity
than heretofore, while the time required for making a joint with my
improved packing is very much reduced. Further, in the case of core
packing, the core is rendered elliptical in cross section by the pressure
round the mandril in the act of coiling, and the longer axis of the ellipse
being thus formed parallel to the piston rod the binding ring employed

page_text: in forming a gland or stuffing box presses this core into a circular one,
thus ensuring tightness around the rod and stuffing box, and with more
regularity than heretofore.
In the accompanying Drawing I have shewn a coil of coro packing
made according to this Invention. The core it will be seen is elliptical
as explained, and the coil or "set" given to the flexible cord is perma-
nent, while at the same time it admits of an indefinite expansion to suit
various diameters of glands or stuffing boxes.
Having now set forth the nature of my Invention of improvements in
the manufacture of piston packing, and explained the manner of carrying.
the same into effect, I wish it to be understood that under the above in
part recited Letters Patent I claim, submitting cords or ropes of india-
rubber packing to vulcanization in a coiled state and thereby securing
for the packing a permanent spiral or helical "set" for the purpose
above explained.
In witness whereof, I, the said Isaac Blue Harris, have hereunto
set my hand and seal, the Thirteenth day of April, in the year of
our Lord One thousand eight hundred and seventy-two.