IMPROVEMENTS IN PISTONS
Year: 1854

page_text: LETTERS PATENT to Jonathan Edge, of Bolton-le-Moors, in the County of
Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN PISTONS."
Sealed the 9th March 1855, and dated the 27th September 1854.
PROVISIONAL SPECIFICATION left by tho said Jonathan Edge at the
Office of the Commissioners of Patents, with his Petition, on the
27th September 1854.
I, JONATHAN EDGE, of Bolton-le-Moors, in the County of Lancaster,
Engineer, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN PISTONS" to be as follows:-
The nature of my Invention consists in an improved construction of metallic
pistons suitable for steam engines or for other purposes. My improved piston
consists of a block furnished with a lid, both of which are bevelled at their
inner edges. Between the bevelled edges of the block and lid is a ring of
copper or other suitable metal, which forms the packing. By screwing down
the lid the packing ring is expanded to fit the cylinder, and I use set screws
to prevent the pressure on the lid expanding the metallic packing ring.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Jonathan Edge in the Great Seal Patent Office on the
26th March 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JONATHAN
EDGE, of Bolton-le-Moors, in the County of Lancaster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of September, in the year of our
Lord One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Jonathan Edge, Her special license that I, the said Jonathan Edge, my
executors, administrators, and assigns, or such others as I, the said Jonathan
Edge, 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
yend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN PISTONS," upon
the condition (amongst others) that I, the said Jonathan Edge, by an instru-
ment in writing under my hand and seal, 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 Jonathan Edge, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, that is to say:-
The nature of my Invention consists in so constructing the metallic packing
of a piston, that the piston lid and block, or either of them, when tightened
together by tightening screws, cause the packing ring to expand, to fit the
cylinder in which the piston works, the said packing ring being a solid hoop of
metal that will yield to pressure, and is not cut, as is customary, in the metallic
packings hitherto employed.
And in order that my Invention may be fully understood and readily carried
into effect, 1 will proceed to describe the means pursued by me, reference being
had to the accompanying Sheet of Drawings, and to the letters and figures
marked thereon.
Fig. 1 is a transverse section through one of my improved pistons; Fig. 2,
a plan of the same. a is the piston block, which is bevilled at its circum-

page_text: ference to fit the packing ring b. The lid c, which fits on the boss of the
piston block in the ordinary manner, is also bevilled to fit the piston ring.
d, d, are four or other suitable number of screws, passing through the lid c and
screwed into the block a; and e, e, are four or other suitable number of set
screws, screwed into the lid c and abutting against the block a. The object of
these set screws is to prevent the pressure of the steam on the lid expanding
the packing ring. When the piston requires tightening, the set screws e are
unscrewed a little, and the screws d are tightened up proportionately; the
bevilled surfaces of the lid c and block a, acting on the ring b, are thus made
to expand the said ring, and consequently to form a steam or water tight joint
in the cylinder in which the piston works. I prefer to make the packing ring
c of a compound, formed of copper, tin, and zinc, in the proportion of sixteen
ounces of copper, one ounce of tin, and four ounces of zinc; but any other
metallic compound that is sufficiently yielding to expand without breaking
may be employed. Fig. 3 is a transverse section of a modification of my
In these views similar letters
improved piston; Fig. 4, a plan of the same.
of reference are put upon the parts corresponding to those in the above-
described piston. In this piston, the lid only is made with a bevilled surface,
The screws d,
and the packing ring 6 is flat where it bears on the block a.
instead of being tapped into the block a, are furnished with nuts d', and the
set screws e are screwed into the nuts e'. The mode of tightening up this
piston is similar to that above described in reference to Figures 1 and 2.
Having thus described the nature of my Invention, and the manner of per-
forming the same, I wish it to be understood that I do not limit myself to the
details herein set forth, as the same must be varied according to the size of
the piston to which my improvements are applied; but what I do claim is, so
constructing the packing ring of a piston without joint that the tightening up
of the lid shall expand the said ring.
In witness whereof, I, the said Jonathan Edge, have hereunto set my
hand and seal, this Twenty-third day of March, in the year of our
Lord One thousand eight hundred and fifty-five.
JONATHAN EDGE. (L.S.)
Witness to the signature of Jonathan Edge,
H. B. BARLOW,
Patent Agent, Manchester.