IMPROVEMENTS IN THE MAXUDATUDE OR DADS
Year: 1858

page_text: LETTERS PATENT to Alexander Angus Croll, of Coleman Street, in the
City of London, Engineer, for the Invention of "IMPROVEMENTS IN THE
MAXUDATUDE OR DADS AD
Sealed the 18th May 1858, and dated the 18th March 1858:
PROVISIONAL SPECIFICATION left by the said Alexander Angus Croll
at the Office of the Commissioners of Patents, with his Petition, on
the 18th March 1858.
I, ALEXANDER ANGUS CROLL, of Coleman Street, in the City of London,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF PARTS OF DRY GAS METERS," to be as follows:-
In forming the valve seats of dry gas meters, it is usual for the width of
the bars or divisions between the passages or openings through them to be
about equal to the width of such passages or openings; but by the extent of
surfaces thus in contact with the valve or cover, it is found that fluid condensed
or formed from the gas accumulates between such surfaces, connecting them
together, and during part of the motion of the valve partially, closing the
passages, so as to obstruct the free passage of the gas, which thereby becomes
irregular in delivery, producing flickering or oscillation of the lights; and to
remedy this evil constitutes one part of my present improvements. For this
purpose I reduce the width of the surfaces or bars between the openings in the
valve seats considerably; and, by preference, retain only such portion of the

page_text: surfaces as is necessary to secure the due measurement of the gas; and, by
preference, I form the centre opening larger than the others.
Another improvement relates to the composition of the alloy employed in
the manufacture of valves or covers, and the valve seats of dry gas meters.
The alloy generally used for these purposes consists of nearly equal parts tin
and antimony, and I have found a great advantage to result in the working of
such parts by adopting an alloy for the valve seats, in the composition of
which tin predominates considerably, say to 6 parts of antimony, I apply
about 16 parts of tin, or thereabouts, and for the valves or covers, say about
8 parts antimony to 16 of tin. But I find it important, in all cases, that
there be a difference in the composition of the alloy for the seats from that for
the valves or covers, as thereby the friction of the surfaces in contact is
materially lessened, and the action of the meter rendered more regular and
certain. And in forming the alloys, I find it important to heat the tin and
the antimony separately before mixing; and whatever the proportions adopted
to combine them at two different times. Thus, supposing I wish to obtain
a composition formed of 8 parts antimony and 16 of tin, I melt fully 8 parts
of antimony (say to a blood-red heat) in one crucible, and 8 parts of tin in
another crucible; amd when both are ready I mix them, and having stirred
them together, I pour the compound thus obtained into moulds or ingots.
This composition 1 again melt, as also the remaining 8 parts of tin (separately
by preference), and having mixed these pour the compound obtained inta
moulds ready for use.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Angus Croll in the Great Seal Patent Office
on the 18th September 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
ANGUS CROLL, of Coleman Street, in the City of London, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of March, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Alexander Angus Croll, Her special licence that I, the said Alex-
ander Angus Croll, my executors, administrators, and assigns, or such others
as I, the said Alexander Angus Croll, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time

page_text: 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 PARTS OF DRY GAS
METERS," upon the condition (amongst others) that I, the said Alexander
Angus Croll, 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 Alexander Angus Croll, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
In forming the valve seats of dry gas meters, it is usual for the width of
the bars or divisions between the passages or openings through them to be
about equal to the width of such passages or openings; but by the extent of
surfaces thus in contact with the valve or cover, it is found that fluid condensed
or formed from the gas accumulates between such surfaces, connecting them
or causing them to adhere together; and that during part of the motion of
the valve, the passages become partially closed by a sort of film, produced by
such condensation, thus adhering to the parts of the valve and the edges of its
seat, so as to obstruct the free passage of the gas, which thereby becomes
irregular in delivery, producing flickering or oscillation of the lights; and to
remedy this evil constitutes one part of my present improvements. For this
purpose, in constructing the valve seats of dry gas meters, where the valves
or covers slide uniformly to and fro over every part of such seats, I reduce
the width of the surfaces or bars between the openings in the valve seats
considerably, and retain only such portion of those surfaces as is necessary to
secure the due measurement of the gas; and, by preference, I form the
centre opening or that for the exit of the gas larger than the others.
Another improvement relates to the composition of the alloy employed in
the manufacture of valves or covers, and the valve seats of dry gas meters.
The alloy generally used for these purposes consists of nearly equal parts tin
and antimony, and I have found a great advantage to result in the working of
such parts by adopting an alloy for the valve seats, in the composition of which
tin predominates considerably; say, to six parts of antimony I apply about 16
parts of tin or thereabouts, and for the valves or covers, say about 8 parts

page_text: antimony to 16 of tin. But I find it important in all cases that there be a
difference in the composition of the alloy for the seats from that for the
valves or covers, as thereby the friction of the surfaces in contact is materially
lessened, and the action of the meter rendered more regular and certain. In
forming the alloys, I find it important to heat the tin and the antimony
separately before mixing, and whatever the proportions adopted to combine
them at two different times. Thus, supposing I wish to obtain a composition
formed of 8 parts antimony, and 16 of tin, I melt fully 8 parts of antimony
(say to a blood red heat) in one crucible, and 8 parts of tin in another crucible,
and when both are ready I mix them, and having stirred them together, I
pour the compound thus obtained into moulds or ingots. This composition I
again melt, as also the remaining 8 parts of tin (separately by preference),
and having mixed these, pour the compound obtained into moulds ready for
use.
Having thus described the nature of my said Invention, and the means
which I adopt in carrying the same into effect, I would have it understood,
that I do not confine myself to the precise details referred to, so long as the
peculiar character of either part thereof be retained substantially as explained.
In witness whereof, I, the said Alexander Angus Croll, have hereunto set
my hand and seal, this Seventeenth day of September, in the year of
our Lord One thousand eight hundred and fifty-eight.
Witness,
WILLIAM BROOKES,
73, Chancery Lane, London,
Patent Agent.
A. ANGUS CROLL. (L.S.)