The North-Carolinian. [volume] (Fayetteville [N.C.]) 1839-1861, 1854-07-15
Scientific intelligence.

| Scientific intelligence.
! IRON SUSPENSION RAILWAY BRIDGEs-Our
article of last week, upon the strength OF this
class of structures, was merely precautionary
and not antagonstic. We not alarmists
and not so strictly conservative as to oppose
everything new out of the old beaten track.
We have for some years been in favor of using
iron for bridge structures, and sincerely depre-
Gated the action of the Directors of tue New
York and Erie Railway, when they banished all
iron bridges from their road. We have not only
written in favor of iron bridges, but have great
faith i'll the eventual adoption of iron for bridge
structures throughout the country. Thus much
for our supposed hostility to iron bridges. We
! are -anx xotis, as is every one who has the good
of the public and of railway interest in view,
that they shall not be prejudiced by hasty or
careless movements. There is strong public
j prejudice against iron bridges, and if this un-
popularity is not sustained 10y facts, then the
public should be set Alright. There are two
sides to almost every question, and III giving IN
very limited space the views of the friends
of the Niagara Suspension Bridge which we
gather from series of articles written for the
Niagara Falls Gazette, are only doing
strict justice. We likewise indebted to
other sources of information for some of the
facts. To connect the Canadian railways with
the New York Central line, at Niagara, can
not be done without suspension bridge The
gorge at this point has to be passed 10y single
span of eight hundred feet in length, at height
of 23O feet from the water. If the suspension
principle cannot be safely used here, it is idle
to think of crossing. The opponents OF the
Niagara bridge have quoted largely of the
bridges that have failed, and below we give
some facts of different nature.
The great suspension bridge at Frbourg, in
Switzerland has single stretch of $50 feet.
1t is the first of so large span ever erected.
1t was built by French Engineer, NJ. Challey,
under all the apparent hazards generally attend
in,r established
and usaycs not yet subjected to the tests of eN-
pertinent, in combination with the application
, of scientific principles. 1t may be regarded as
the primitive work of its kind, and it would not
be strange if, examination of it, at the pres
ent era Of advanced progress, it should be found
| open TO criticism in some of the tails of con-
structon. Yet this bridge completed III
1882, and has therefore been standing i'll
nearly 24 years. Its strength was severely
tested before it was opened to the public, first
| with sand then with train of artillery, and
lastly with multitude nearly covering it from
shore to shore.
The Menai chain bridge, finished in 1921,
sustained at one time some damage by storm
22%n to the asneifsnsY in of staHf This defect
red in it--thirty years in use.
The Han,merSmith chain bridge, across the
Thames, has stood about twenty years. The
Hungerford, across the SINE, and the Mont
rose, in Scotland (the latter having a single
span of 500 tcet,) have both stood several years.
But the chain bridge across the Danube be-
tween Pesth and Ofen, in Hungary, affords
one of the most triumphant examples of the
strength of such a work. During the late
Hungarian struggle two retreatng armies,
sisting of infantry, cavalry hnd heavy artillery
trains, crossed it in safety, hotly pursued by
the lied Austrian and Russian forces. 1t was
built by Mr. Clark, an English engineer, and is
made up of spans varying from 25O to 45O feet
| hrid q @
span ever survived trial this.
| In this country, we have the great suspension
agueduct over the Allegheny, and the wire
cable fridge over the Monongahela, at Pitts
ourg, both OF which are yet standing and have
stood some fourteen years. The Mononrahela
is known to be the great avenue between the.
city on the one side, and the iron works and
coal mines on the other. During the hours of
business 1t is constantly sustaining an enormous
weight. These two last are the works of Mr.
ROcbllng, the same gentleman who is now
erecting the Niagara bridge, well as another
for railway trains across the Kentucky river
This last is 200 feet long.
The reason given for the failure Of the Wheel
ing Bridge of 1900 feet span is, that it was
not properly stayed and guyed. The weight Of
he structure was supposed to be great enough
to resist the vertical and lateral force of the
wind. 1t is held by engineering authority,
that the safety of properly constructing suspen-
sion bridges depends upon stays and braces to
check unuulatiOnS and vibrations consequent
upon the force of severe Winds the movements
Of troops and the passage Of locomotives. 1t
is stated that the Wheeling Bridge moved some
twenty-five thirty feet at each blast of the storm,
rising up slowly, and then falling with such ter
r.ble force that the chain cables were twisted
off and the main structure fell into the river.
1t is likewise held that if the bridge had been
properly :yed, so us to prevent oscillation, il
would have outrode the storm in safety.
!. ~~~~>~>~>>~~~~~~~~>~~~~~
: ingenious ESCAPE FROM PRIsoN.-The escape
Of Squrcs from the New Hampshire State pr-
son. where he was sentenced to fifteen years
fnement, was most ingenious The prisoners
march to breakfast and returning, enter their
cells, which close with spring, while the turn
4 key follows and locks outer lock. Each in
mate holds his hand up to the bar above th'
door the officer does this, who duly counts
s aud reports the inmates to the warden. Squrc>
made, out of sole leather, very ingeniously-
wrought hand, not forgetting to carve out the
Q finger-nai and give them as well as the hngerS
+ very natural and life-like appearance by the
use of "a bluish-whte powder. On the morninG
* of his intended escape, he fixed his limitations
: hand to the CRATE of his celldoor, making It's po-
" sition more secure by the use OF shoemakerS
= way On returning lie closed the door the sane
! ! as though he had gone within, and pulled the
= = the door to after him, required. The turnkey
followed counting the upraised hands as he
, marched through the corridor, and reported
, that all was right The prisoner then passed out