IMPROVE- MENTS IN THE MANUFACTURE OF TUBULAR FLUES OF LOCOMOTIVE AND OTHER STEAM BOILERS
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
Porrs, of Birmingham, Brass Tube Maker, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of
Great Britain and Ireland, bearing date at Westminster, the Tenth day of
April, One thousand eight hundred and forty-eight, in the eleventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Thomas Potts, my exors, admiors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Thomas Potts,
my exors, admors, and assigns, or such others as I, the said Thomas Potts,
my exors, admors, or assigns, should at any time agree with, and no others,
from time to time and at all times during the term of years therein expressed,
should and lawfully might make, use, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, my Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF TUBULAR FLUES OF LOCOMOTIVE AND OTHER STEAM
BOILERS;" in which said Letters Patent is contained a proviso that I, the
said Thomas Potts, should cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, by an
instrument in writing under my hand and seal, to be inrolled in Her Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the
same, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Potts, do hereby declare that the nature of my said Invention, and

page_text: the manner in which the same is to be performed, are fully described and ascer-
tained in and by the following statement thereof (that is to say):-
In the use of tubular flues of locomotive and other steam boilers, when
made of copper or of brass, I have observed that the brazed or soldered joints
have not been so prejudicially acted on by the friction consequent on the sharp
grit from the fire being carried through by the draft; and I have discovered
that by lining the whole interior of the surface of a copper tube, or a tube
made of an alloy of copper with a similar description of metal to that now used
for simply brazing or soldering the joints, an improved manufacture of such
flues results. In carrying out my Invention I take what is called "Bath
metal," compounded of three parts of best selected copper, two parts of foreign
zinc, and ten ounces of refined tin, for every hundredweight of the Bath
metal, rolled out into a plate or strip, which I form into a tubular shape of
the size required in the ordinary manner of making tubes, the edges butting
together, and I anneal such tubes and stretch them in order to straighten
them and that the edges of each plate may come correctly together. On each
of these tubes I place by preference a tube of copper, but it may be of an
alloy of copper, the outer tube going readily on to the inner or lining tube. The
compound tube thus prepared I put on to a taper mandril of steel with a taper
of about one sixteenth of an inch in its length, which not only facilitates the
withdrawing of the mandril, but also gives additional thickness to the end of
the tubular flue which comes next the fire-box..of the steam boiler. These
compound tubes are then drawn with the mandrils within them through dies
or draw plates, as is well understood. I have not found it necessary to solder
the inner tube or lining of Bath metal, the strength being sufficient without,.
and the water is prevented passing through by reason of the outer tube being
complete.
I would remark that I do not confine myself to the exact proportions of the
composition of Bath metal, neither do I claim the making of Bath metal, but
only the use of a lining of such a preparation of metal to the lining of tubular
flues of copper and of copper alloyed, the object being to obtain a lining of metal
which shall be less prejudicially acted on by the passage of sharp grit from the
fire than if the whole tube, as heretofore, were made of copper or of copper
alloyed. And in using such lining I prefer to make the lining of about two
thirds the thickness of the finished tube, and the external tube about one third
the thickness of the finished tube.
In witness whereof, I, the said Thomas Potts, have hereunto set my hand
and seal, this Fifth day of September, in the year of our Lord One
thousand eight hundred and forty-eight.
THOMAS (L.B.). POTTS."

page_text: AND BE IT REMEMBERED, that on the Fifth day of September, in
the year of our Lord 1848, the aforesaid Thomas Potts came before our said
Lady the Queen in Her Chancery, and acknowledged the Specification afore-
said, and all and every thing therein contained and specified, in form above
5 written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.
Enrolled the Tenth day of October, in the year of our Lord One thousand
eight hundred and forty-eight.