Aberdeen herald. [volume] (Aberdeen, Chehalis County, W.T.) 1886-1917, 1911-12-11
NATURAL BRIDGES
We Can Boast of at Least Nine
of Them In This Country.
OUR FIRST WOODEN BRIDGES.
They Were Built About 1900 In the
Eastern and Central States, and Then
Came the Covered Structures-Few
Iron Bridges Prior to 1850.

Came the Covered Structures-Few
Iron Bridges Prior to 1850.
Nature has provided this country
with at least nine natural bridges. one
in Virginia with a span of about nine
ty-three feet and about 300 feet hi-h
one in Alabama with il span of about
seventy feet and about 1870 feet high
five in California. the largest of which
has IL span of about eighty feet and is
about twenty feet high: one in Ken
lucky with IL span of about seventy
feet and about 1870 feet high, and one
In southern Florida Of somewhat
smaller dimensions.
Bridge building in the United States
is of comparatively recent accomplish
mcnt The early settlers We're com
PEELED to ford the streams or cross
them on RATS or in dugouts. When
Washington crossed the Delaware with
his army there were no bridges over
that river. ANA history records nany
instances of streams being f0rded with
untold hardship ana the consequent
disasters and delays. Such incidents
become serious matters when. for eX
ample. physicians are unable to reach
the sick or injured because of impasS-
able fordS or are compelled to expose
themselves to unnecessary danger.
Traffic conditions in general are de-
moralized by unsafe bridges OF cul-
verts
Pontoon bridges have served tempo
rary need in many instances, but eSpc-
cially in warfare Mention Is made of
their use very early in history. and one
Of the most notable occasions was
when the Persian army under NerXes
crossed the IIellespont on two pontoon
bridges consisting, one of $50 vessels
and the other of 31l These were an
chored head and stern alongside of
each other, with their keelS in the di
rectiOn Of the current
The Romans had Wickcrwork vessels
covered with hides destined TO support
the timber platform Of bridge. These
formed part Of the train of their ar
mics throughout the history of the en-
pirc until 1IG y. ID.
The construction of highway bridges
in this country began to assume prac-
teal proportions about the year 1900,
when many wooden bridges were built
in the eastern and central states by
Theodore Burr and Timothy Palmer
The wooden lattice truss was intro
duced about 1920 by lthiel Towne.
Many of these bridges, consisting of
plankS pinned together in lattice work,
were built from this time on, and they
became well known as 'ToWnc' or
"covcred' bridges. 1t is doubtful if
much attention was given to econom-
i.al design. An effort WAS made to
protect the trlSSes from the weather
by wooden roofs and sides in some in
stances. but very few We're ever paint
ed to preserve the timber This early
type of bridge did service for many
years. ana some are still in existence
in Indiana and elsewhere
The Grst covered bridge to be built
IN Tinpecanoe county and one of the
first in central Indiana was the
Brown street bridge over the Wabash
river at Lafayette. according; 10 the
records on file in the Office Of public
roads. department Of agriculture This
old structure. that had been condemn
ed for Il good many years. has long
since disappeared. However, a mum
Der Of covered wooden bridges that
were built more than a half century
ago are still being used within Il RAJ
dius of fifty miles of indianapolis
Few iron bridges We're built in this
country prior to 1870. and it was only
in 1917 hat the first publication in the
United States. discussing the rational
design of bridge members. was issued
by Squire Whipple of Utica. \. y.
Wrought iron began to replace cast
iron about 1863. but steel was not used
until about ten years later. The ad-
vantage of steel over cast or wrought
iron lies in its greater tensile strength.
"Forcmost among structures repre-
sentiug some of the attractive as well
as substantial features in good bridge
DESIGNING of the present age may be
mentioned the Washington bridge over
the Harlem river in New York; said
the superintendent of construction of
bridge engineering. office of public
roads, Washington. "ThiS bridge has
two middle arches of steel. each 80
feet in clear span. and seven masonry
arches, each with Il sixty foot span
It's total length is 1910 feet. while
the width of its roadway is eighty
feet. and its height above mean high
wafer is 1J1 feet. 1t was built at Il cost
Of 50. $50. goo. "-IndianapoliS News.