The Abbeville press and banner. [volume] (Abbeville, S.C.) 1869-1924, 1902-07-30
peR,Ls or sRIpce.euILpINc.
More Hardship and Danger Than In Al.
most Any Other Calling.


The design OF q long bridge span =
one Of the most elaborate mathemati-
cal problems that arises In construc'
tive work. The stresses produced by
Its own weight. by the weight Of traffic.
by locomotive drivers. by the hammer
Ing Of hattened wheels. by the action
Of brakes on IN express train. hy the
high speed on Il curved track. by the
wind and by the expansion and con-
traction Of the steel in summeranI win.
ter. are all accurately calculated. The
DETECTION Of the loaded and ualoaded
bridge Is determined. and complete
drawings are made Of every member
OF II. The bars OF steel are tested In
machines which will pull In two q
horsehair or a steel bar strong enough
TO lift half score OF the heaviest loco.
motives NJ once. and which will crush
m eggshell or 4 steel column and ac'
curately measure the stress In each
case. The different kinds OF members
are forged. riveted. bored or planed In
perhaps half dozen remote shops.
and. although usually not fitted 10.
gether there. are examined and meas
ured by specialists 10 see that they are
correct. and are then shipped by scores
of carloads to the site OF the proposed
structure. where steam derricks unload
them and pile them many feet high In
stacks covering acres CT ground.
The bridge piers may rise above the
water. hundreds Of feet apart. 1t re.
mains to place on them 1000ton
structure. high above savage chasm.
over an impossible current or roaring
tide. where the water Is deep. the bot.
tom Of jagged rocks or treacherous
qu!cksand. or where an old bridge
mus, be removed. and the new ono
built in its place without interrupting
navigation or obstructing continuous
traffic on the bridge. To accomplish
this tho engineer has timber. bolts and
ropes. ho:sting-cngines. derricks and q
band OF intrepid builders. who have
perhaps followed him for years
through more hardship and danger
than fall to the lot Of almost any other
calling.
The complicated framework OF n
great span Is skeleton with many &C.
curate joints and thousands Of steel
sinews and bones. each OF which must
60 In exactly the right place In exactly
the right order. The builder must
weave into the trusaes pieces larger.
heavier and far more inhexible than
whole trea.trunks: swiftly hoist and
swing them 10 place hundreds Of feet
high: fit together the massive girders
and huge forged bars with watchmak.
er's accuracy; support the unw!eldiy
masses until they are keyed together
and self-sustaining. and under millions
OF pounds Of stress must adjust them.
at dizzy heights. TO mathematical lines
This he may need to do. not deliber
ately in n comfortable shop or on g
solid platform. but in dangerous cmer.
c:es. at utmost speed. putting forth his
whole strength on narrow. springing
planks, in a furious tempest, In bitter
cold or In blazing heat. He may be in
the heart OF IN African desert. men,
aced by bloodthirsty fanatics. or In 4
gorge Of the Andes. hundreds OF miles
from tools or supplies. where there Is
absolutely no supplement TO his own
resources. Under such conditions bridge
building is one OF the most fascinating
and difficult Of engineering problems.
and requires different solution for A.
most every case.-Frank W. Skinner
IN tEr Century.