The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1897-04-04

foundations. Tie building itself is after
all a super structure. It is the tousle
ton that requires the engiueers great
est skill, FOR sometimes the chEditions
are most adverse. Eor Instance, il low
er New York water IS encountered at
very shallow depths. ana ii is in this
lower section that most CT the sky
scrapers are ha:is- The Commercial
cable building is Is. stories high. It's
foundation floor IS IS fest 3elaw t.se
surface water leseI and at least u feet
below river Level. Yet the lowest sub
cellars are. SO TO speak. as dry as punk.
Ii was accomplished by means Of the
intricate and extended caisson system.
TIE water is entirely excluded. When
such low levels are reached the con-
tractor has really as much. to do in
preserving the integrity of the sur
rounding buildings and streets as he
has in economically carrying on his
excavations. The laws are very string
ent in regard 70 q cavein and municipal
lawsuits are sure to drain ones
pockets. In some places, however, in
spite of the most extended Snoring
up" there is sure TO be a curve in the
nearby street lines. Recently in New
York. at a deep excavation, a person
could by going some distance up, gaze
along the car tracks and discern part
of an immense quadrant, formed by
the tracks where they had followed the
sinking of the ground toward the eX-
cavation.
Why does not a big building topple
over? is the question asked by the OBJ
server 1t would seem that the action
of the winds. rain. sun and elements
generally ought to cause it to fall. 1t
could not fall for several reasons. In
the first place, every part of the struc-
ture is bolted to the adjoining parts
,-,x~ toI in,
serted red hot, and which, as they cool,
draw the various pieces of steel to-
gether with a force that almost accom-
plishes molecular adhesion. The build
ing thus becomes unit above ground.
Below ground, as has been pointed out,
the caisSon system of construction adj
mits of no disintegration. On the other
hand, the line inside of which the
center of gravity exists lies so far out
side the building that it could not pos
sibly topple. The basement construc-
ton is such that the whole affair re-
sembles a telegraph pole, which would
first have to get out of it's hole in the
ground before it could fall. The same
conditions exist in turnstile bridges.
The base or pivot on which the bridge
turns is so broad that the outstretched
arms could not possibly tilt the whole
structure. In the new Third avenue
bridge in New York city each arm ex-
tends out 120 feet beyond the central
turnstile In order TO topple, sufficient
weight would need to be placed on one
arm to overcome the weight of the
other arm and the heavy central base.
AS the bridge weighs, all told, nearly
1000 tons, this would be practically
impossible.
WEIGHING BY COMPUTATION.
A piece of heavy ordnance is hung on
its trunnions merely by calculation.
The center of gravity is needed. of
course. The center of gravity of every
part of the gun is calculated first. Then
the relation of these centers to the
general center is ascertained by cOmpu-
tation. Engineers are able to determ-
inc it within a small fraction of an
inch In short, the weighing of pom
da,.o,1S objects iS M RI of q Snanial sci