National Republican. (Washington City (D.C.)) 1872-1888, 1875-03-01
COST, STRENGTH AND DURABILITY.
THE PROCESSES OF MANUFACTURE.
Complete eseriptIOh OF the Work In
all its Branehes-The New Bridge
over the AnacOstia River
Now being Built.

Boston, Mass, there is a tombstone conmemorat-
ing the claims OF the departed worthy who lies
below, to the eternal gratitude Of posterity. The
inscription is dated in the early part Of this GEN.
fury, (sbout 1901 but the name Of him who was
thus immortaliLed has faded, like the date Of his
death, from our memory, while the deed for which
he was distinguished, and which was recorded
upon his tombstone, remains clear.
HE built the famous bridge over the Charles
river in this town." says the record.
The Charles river Is here q small stream about
twenty or thirty feet wide, and the bridge was
simple wooden structure.
Doubtless in its day this structure was consid-
cred an engineering feat worthy Of such posthu-
nous Immortality as is gained by an epitspb, and
afforded such convenience for transportation as
was needed by the commercial activity of that
TSieb have oecnTrs m onP and ndss
trial methods are so fully indicated by the
changes OF our manner and method OF bridge
building that 1t will not be loss Of time to lnyes
tigate the present condition Of our abilities in
this most useful branch Of engineering skill.
In the usual archaeological classification OF eras
the Stone Age precedes that Of Iron and in the
history of bridge building the same sequence has
been preserved. Though the knowledge of work
historic period, yet In quite modern timss-Wfthn
this century even-the invention of new processes
and the experience gained Of new methods have
SO completely revolutionized this branch of indus.
try, and given US such mastery over this mate
rial nabling us to applyit to such new uses that
the present century.
Tie knowledge Of the arch as a method Of con-
struction with stone or brick-both of them mate
rails aptly fitted for resistance under pressure,
but Of comparatively no tensile strength-enabled
the Romans to surpass all nations that preceded
them in the course Of history in building bridges.
THE BRIDGE ACROSS THE DANUBE.
erected by ApoIIodrus the architect of Trajans
column, was the largest bridge built by the
Romans 1t was more than three hundred feet
in height, composed Of twenty-one arches resting
~HNVnr oh NaEr
feet in length. It was after a few years de-
stroyed by the Emperor Adrian, lest it should
afford means $50; Of passage to the and
With the advent Of railroads bridge building
became even a greater necessity than it had ever
been before, and the use Of iron has enabled en-
gineers to grapple with and overcome difficulties
which only nifty years ago would have been con-
sidered hOpeleSsly insurmountable.
In this modern use Of iron advantage Is taken
Of its great tensile strength, and many iron
bridges, over which enormous trains Of heavily
loaded cars pass hourly, look as though they
were spun from gossamer threads, and yet are
stronger than any structure of wood or stone
would be.
Another great advantage of an iron bridge
over one constructed Of wood stone is the
greater ease with which it in every part Of 1t
be constantly observed and every falling part re-
Whatever material may be used, every edifce
is always subject to the slow disintegrating in
fuence Of time and the elements. In every such
ediice as bridge, use is o process of constant
weakening, which, if not as constantly guarded
against, must inevitably, in time, lead to Its de-
In wooden or stone bridge beam affected by
dry rot or stone weakened by the effects Of
frost may lie hidden from the inspection Of even
the most vigilant observer, until, when the pro-
cess has gone far enough, the bridge suddenly
gives way under a not unusual strain, and death
and disaster shock the community into q sense Of
the inherent defects Of these materials for such
structures.
The introduction of the railroad has brought
about also another change in the bridge building
Of modern times compared with that Of all the
ages which have preceded this nineteenth CEN
fury. The chief bridges Of ancient times were
built as great public conveniences, upon thorough
ways over which there was q large amount Of
commercial centres which attracted such trsvsI
and were therefore, placed where they were seen
by great numbers.
Now, however, the connection between the chief
commercial centres is made by the railroads, and
these penetrate Immense distances, through COM
paratiYely unsettled districts, in order TO bring
about the needed distribution; and in conse-
quenoo many ofthe great RAILROAD bridges are
built in the most unfrequented spots, and are un-
seen BY the numerous passengers who traverse
pass as objects Of intelligent interest many Of the
sights they may be travelling to see.
THE VARIOUS PROCESSES
by which the iron is prepared to be used in bridge
building are, many Of them, as new as is the use
Of this material for this purpose. Taking train
by the Reading railroad from Philadelphia, we
arrive in about an hour at Phenixyille, in the
Schuylkin Valley, where the Phoenix Iron and
Bridge Works are situated. In this establishment
we can follow the iron from Its original condition
iisSment in this country, and most probably in
the world, where this can be seen. These works
were established in 1870. In 1877 they came into
the possession Of the late David Reeves, who, by
bis energy and enterprise, increased their capac-
ity TO meet the growing demands Of the time,
ing constantly over 1,500 hands.
The first process in melting ore is the blast
furnace. Here the ore with coal and Aux OF lime
fires, driven by hot blast and kept burning night
and day. The iron, as 1t becomes melted, flows
to the bottom Of the furnace, and is drawn of
below in o glowing stream. Into the top Of the
blast-furDaces the ore and coal are dumped, hav-
ing been raised to the top by an elevator worked
The blast for the furnace is driven by two enor-
nous engines, each Of three hundred horse power.
The blast used here is, as we have said, a hot
the gases evolved from the material ITSELF
From the earliest times the blast of bellows
Of the combustion BY more plentiful supply Of
ire blast furnace is supposed to have been first
into England in 1858. Next came the use of btu
minoUs coal urged with blast Of cold air. Bat
it was not until 1879 that Nelson, Englishman,
conceived the idea Of heating the air of the blast
In that year he obtained patent for this process
and found that he could from the same quantity
Of fuel make three times as much iron. In HIS
method, however, he used an extra FIRE for heat
ing the air of the blast In 1887 the idea of heat
ing the air Of the blast by the gases generated In
the process was first practically introduced by NJ
Faber DuGour, in the kingdom of Wurtemberg.
In this country charcoal was at first used uni
Ttrsally for smelling iron, anthracite coal being
considered unfit for the purpose. In 1871, q. E.
Detmold adapted the consumption Of the gases
produced BY the smelling to the use of anthracite;
and since then it has become quite general, and
has caused an almost incalculable saving to the
| community in the price Of iron.
Twice every day the furnace is tapped, and the
STREAM OF LIQUID IRON
flows out into molds formed in the sand, making
the iron into pIgs-so called from fanced resem-
blance to the form Of these animals. This makes
the hrst process, and In many smelling. establish
ments this is all that is DONE the iron IN this form
being sold and entering into the general consump-
tion.
The next process is "boiIing, " which is q modi-
fcation Of pudding" and Is generally used in
OF pudding was Invented BY Henry Cort, an
Englishman, and patented by him in l7S3 and
lISt, az new process ior ''shingin Welding and
and rods Of Purer quality and in larger quantity
than heretofore, by more effectual application
When iron is simply melted and run into any
mold Its texture is granular and 1t Is 20 brittle
as 70 pc quite unreLaoIe ior any use requiring
consisted in stirring the molten iron run out into
a puddle, and had the effect of changing its
atomic arrangement as to render the process Of
The process Of boiling is considered an improve
ment upon this The boiling furnace is an oven
blast. The cast-iron sides are double, and q con-
slant circulation Of water is kept passing through
| the chamber thus made In order to preserve the
| structure IRON fusion by the heat The inside is
/ lined with friedrich covered with metallic ore
4 and Stag over the bottom and sides, and then the
oven being charged with the pigs OF iron the heat
is let on The pigs melt and the oven Is filled with
/ molten iron. The puddler constantly stIrs this
mass with bar let through hole In the door
until the iron boils up, or "ferments," as It is
4 called.
| This fermentation is caused by the combustion
Of portion Of the carbon In the IRON and as soOu
the excess Of this is consumed the cinders and
\ Stag sink to the bottom Of the oven leaving the
/ semi-fuid mass on the top. Stirring this about
the puddler forms It into balls OF such size as
he can conveniently handle, which ara taken out
and carried on little cars, made to receive them,
| to the "squeezer."
IN the squeezer the glowing ball Of uhitehot
/ iron is placed, and forced with a rotary motion
| through spiral passage, the diameter of which
Is constantly diminishing. The effect of this op-
GRAFTON is to squeeze all the Stag and einder out
Of the ball and force the iron assume the sh ape
| Of a short, thick cylinder called "bloom." This
| process was formerly performed by striking the
| ball repeatedly with a tilt-hammer.
| The bloom is now re-heated and subjected to
the process Of rolling. "The rolls" are heavy.
cylinders of east-lron placed almost IN contact
and revolving rapidly by steam power. The
bloom is caught between these rollers and passed
backwardand forward until it is pressed into a
bar fnrfr 10 sfw tno tn