The Sun.
London, England, 1850-03-29 00:00:00

INSTITUTION OF CIVIL ENGINEERS.

On Tuesday, March 26, 1850, William Cubitt, Esq.,
President, ,in the Chair, the, first paper read was a
" Description of the Chapple Viaduct, upon the Col-
chester and Stour Valley Extension of the Eastern
Counties Railway," by Mr. P. B ruff, Assoc. Inst. C.E.
This viaduct was thrown across the valley of
the Colne, at Chapple ; it consisted of 32 semicircular
arches, each of the span of 30 feet, the total length
being 1,136 feet, and the extreme height from the
foundations to the rail level being 80 feet. The aver-
age height of the piers from the foundation to the
springing was 45 feet ; they were 27 feet 3 inches
wide by 4 feet 10i inches thick, at the under side of
the impost, and tapered downwards to the plinth, with
a batter of 1 in 36; twenty-three of the piers only had
plinths, which consisted of a set-off of 2} inches,
making the dimensions of the base of those piers 29
feet 6 inches wide, by 7 feet 1 inch thick. The
piers
.were solid below the plinth, but above that level
there was a centre opening 6 feet in width, arched
at the top and the bottom. The whole of this via-
duct was constructed of bricks made in the district,
being chiefly set in mortar, but the arches for a die-
tance of 4 feet 6 inches above the springing were set
in cement. • The viaduct occupied about twenty months
in construction, and cost about 551. per lineal yard.
The next paper read was " On the Manufacture of
Malleable Iron, with the results of Experiments on
the Strength of Railway Axles," by Mr. G. B.

Thorneycroft, Assoc. Inst. C. E. It was stated that
malleable iron might be dividfd into tcso distinct
classes, " red short" and " cold short ;" the former
being generally produced from the rich ores, and the
latter from the poorer or leaner ores. The pig iron
made from the rich ores (under the cold blast process
only) was not so fluid as that from the lean ores, but
whe❑ converted into malleable iron it became tough
and fibrous, though it was troublesome to work at less
than a white heat, which bad caused it to be denomi-
nated " red short." On the other hand, the pig iron
produced from the lean ores possessed greater fluidity,
but when malleable it was unfitted to support sudden
shocks, or continuous strains, and was hence termed
" cold short." It was furth'r stated, that in the
manufacture of malleable iron very much depended
on the quality of the fuel used in the smelting fur
nace, and in the sub qaent processes ; also that iron
became chrystalline from two causes; first, in con-
sequence of being made from naturally euld short pig
iron, and secondly, from a peculiar manipulation
during the process of " puddling."
The introduction of hot blast fur smelting iron,
rendered necessary a careful investigation of the com-
parative use of hot and cold blast pig iron, in the
manufacture of bars, from which it appeared, that if
the same quality of materials was used in both cases,
equally good bar iron would be produced, though it
was more difficult to convert hot blast pig iron into
"number one" bars, and the waste was greater. It
was certain, that whilst good grey pig iron could
only be produced, by cold blast, from the best mate-
rial., iron of apparently excellent quality could be
made, by hot blast, from the most sulphurous ores
and fuel : indeed to this alone must be attributed
the bad reputation of hot blast iron, for certain
purposes.

_
As it had been asserted, that the peculiar charac-
teristics of malleable iron were to be attributed to the
ore from which it was produced, and not from the
different nature of the processes used in its conversion,
which the author had always believed to be the true
cause, he had, at his works near Wolverhampton,
made bars of the finest crystalline and of the strongest
fibrous texture from the same Yorkshire pig iron.
Another cause which induced great changes in the
texture of iron, when cold, was compression, or im-
pact, which would completely alter its texture from a
fibrous to a crystalline character, as was well
exemplified by the "gag" and the puddling tools
used by forgemen, and in several parts of different
kinds of machinery the same effect was observed.
The author then proceeded to draw attention to
the best shape for railway axles, so as to combine the
greatest strength with the least material, illustrating
his views by the details of a series of experiments
made for determining the question. It would appear,
that railway axles should be made parallel, from
journal to journal, without any shoulder and with
just ►uflicient strength to prevent any vibration in ro-
tating. The experiments showed, that an axle with-
out a shoulder was better able to resist impact, than
one with a shoulder, in the ratio of 155 to 55, and by
leaving the axle parallel, its strength compared with
the same sized axle reduced in the middle was as 5
to lf.

Ttie discussion on this interesting subject was an-
nounced to take place at the next meeting, of Tues-
day, April the 2d, when the monthly ballot for mem
bers would take place ; and the following paper would
be read, " Description of a Lift Bridge on the Thames
Junction Branch of the London and Brighton Rail-
way," by Mr. R. J. Hood. M. Litt. C. E.