The daily Alaskan., 1912-01-31
NATURAL BRIDGES
We Can Boast of at Least Nine
 of Them h This Country.
OUR FIRST WOODEN BRIDGES.


 Eastern and Central States, and Then
 Came the Covered struetures--Fev
 Iron Bridges Prior to 1850,
 Nature has provided th.s country
 with at least nine natural bridges, one
 in Virginia with a span Of about nine
 v-three feet and about 200 feet high; one in Alabama with a span of about
 seventy feet and about lSo feet high; ! five in California. the largest of which has a snsn of about eighty feet and is sbaut twenty feet high; one in Ken uekv with span of about seventy f.ef and about l30 feet high. and one in southern Florida of somewhat smaller dimensions.
 Bridge building in the United States is of comparatively .cccBt accomplish mont The early settlers we're com
 renca to ford the streams or cross
 rb,m au rafts or in dugouts When
 Washington crossed tbe Delaware with his arme there were no bridges over rH4f river and history records many instances or streams being forded wiia
 untold hardship aud the consequent disasters and delays Such incidents ra.ane serious matters when. for OK gwuIe. uhvsieiHuS are unable Co reach fra sick or injured because uf impass able f1-ls or are comucIe5 tn cSuase themselves tD unnecessary danger.
 T~rH. conditions iu general are de uauaeH ny unsafe hrdErs "r 'n.-
 yorts.
 ronaan rf3.rs Hne served tempo
 rs-y med fu m7av iusa0 cs. lon. c~pre gie.rv ta warrr rre. Mention Is made of trr.r r-, rer. parlv fH history. and one Of r-a uas- uotah., ugcaSiou~ wos when I.. Persian army under NrNc> crossed t.e TIcHcsHnn uu two Uontoon ! brsf..s ran-,~..al. ..e ur "co vessels and srr u.rrr al @lE These were gn- .nr~al uar6 and stem nIHn-~i3e of each other with their Reels in Inc 5i- -a.s-n eT the .uH.u...
 The EnnauS lad v5.'er-~ vessels -rva-eF ri.r hides an~ .Hn5 ,n support . the ts.an~ platform uf .Ir.1-a These formed part of rno f-.5n y. tha.r ar
 mics frrruahanl tr. '.- rE nf the em- . ar-a unHl #-5 Alb.
 Tho construction ur h.-hvsy bridges tn t'ss country began lo assume prac- Hrrr --.rauFaus arau, tH, year 1Soo
 when many wooden l-i1gos were built
 in tra eastern and gcnm. states by Theodore Burr and Timothy Palmer Tho wooden lattice truss was intro
 laced about IS2o by Ithiel Towne. ] Many or these bridges. consisting of blanks pinned together in lattice work,
 were huHt from this tIwo ou, and they 1 rrrawa well known as "Towuc'' or -covaryI" bridges. It Is dsumfU' f mrea attention was given Co ceouoU- ieaI design Au CGort was made to rr4-rrr gro t-uSscs from The weather ! l.v wooden roofs and sides iu some i0. ! stance. but very few were ever paint
 cl t1 preserve tho timber. This early ! tyne of bridge did sa-vir go for many wears. and some are .sti1 ia existence ! ia Ir1rua and c'scwhcN.
 Tho first covered bridge Co he hnHt s7 TD-cclrre county and one of the first ia central Indiana was the ! Brown street bridge over the Wabash river at Lafayette. according Jo the
 records oa lIc in tne office at public roads. department of agriculture. This old structure. that had been condemn e6 for good many years. has long since disappeared TIowcver, a mum ! her nF la~craI wooden ar.3rrs tha
 were Hunt more than a half century ago are stG being used within a ra- Iirs of fE.y miles of Indianapolis ! Few iron bridges were built in this country prior to T~To and it was only ] in 1sr- that the frSt publication In the ] United States. discussing the rational ] drer-r of bridge members. was issued ! hv Squire whinpIe or JdCo, \. Y ! yvr.uant iron began to replace cast
 iron rnrrt l0Eg. hut steel vas not uscd
 u~tH rnaut len wears later The ad- ! vrua-n af steel over east or wrought ] iron 1fcs iu }ls greater tensile strength
 "To-mrst among structures rCpre- !. sen.f-- some of the attractive os well ! as substantial features in good bridge 1 H-sfenIr- ,r tNe present age may he mentioned rBc Washington bridge over
 the Harlem river in New York said ! v.e superintendent of construction Of |. h~f3rc engineering office of public
 roads. Washington. This bridge has
 TWO miEafe arches of steel each 5lO ! feet in clear span. and seven masonry
 arches each with a sixty foot span.
 Ttg total lencth Is 2,2T5 feet while |fre with or its roadway is eighty
 feet and its height above mean high ! water Is fal feet. It was built at cost ] of S2. .Ss0Oa0 ''-1udianaroIis News.