Evening star., 1935-01-06

- year. the. increasing number of sky
X scrapers in large cities Is causing our
n Government grave concern. VIII these
giant structures stand the gaf over
long periods Of time in the face OF
constant strain caused by storms wind and
weather? Are some Of them top-heavy, un-
wieldly, actually in danger Of toppling over? Are
the materials and underpnningS strong enough?
These questions were brought to the official
attention of Bureau Of Standards scientists
three years ago. But not until the other day
we're they even in a fair way Of being solved
thanks to what undoubtedly is as novel re-
search program as was ever attempted by Fed
eral investigators This included the conStruc-
ton Of "toy city Of New York." which, when
placed in the 10-foot wind tunnel at the bureau,
Stimulates in remarkable fashion the exact be-
havior Of tall structures, including New York's
Empire State Building, worlds loftiest, during
terrific storms.
Unlike anything ever made before is Little
Old New York" as the model city is nicknamed
The product Of the ingenious mind Of Prof. c.
L. Harris. engineering wizard Of Penn State
College, who worked with Federal specialists
for an entire year while on leave of absence
from his own institution, the miniature city
includes about 80 "skyscrapers" in the neigh
borhood Of the Empire State Building. About
six entire blocks are included-not all the
big city's tallest structures, but those around %
stories high.
ALL models, made Of blocks of wood, are
approximate to scale the ratio being about
one to $50. For instance. a building 1900 feet
high in actual size is represented in block
about foot tall. The Empire State Building
is also in scale, the model being feet high,
whereas the structure itself Is 1250 feet high.
On this scale the height of man would be
0 little more than one-quarter inch. The EN-
pre State Building model is built Of aluminium
plates to the exterior shape OF the real build
ing. omitting minor Irregularities of the surface.
OF course the model does not represent the
actual structure in material, method Of con-
struction or strength.
One Of the most important discoveries made
by the Government Investigators Is that the
surrounding skyscrapers are able to shield the
Empire State Building from wind buffeting and
that it in turn shields them. The neighboring
buildings are considerably lower than the
worlds highest, but they can materially slow
up the furious blasts as they threaten to strike
In all their fury while approaching at speeds
close to 100 miles an hour from the New Jersey
fats and the Atlantic Ocean.
What effect does lightning have on Americas
skyscrapers? Fortunately for the welfare of
millions, not very much, if We are to Judge from
what has happened in recent months to the
Empire State Building. In the midst of severe
nnnoerstormS, lightning bolts, ON three sue
cessive occasions, struck the metal moorng
mast that tops the structure 1850 feet above
the ground. In ea'1 instance the bolt grounded
harrnlessly in a food Of flame thereby giving
the Empire State Building the unofficial title
OF 'the largest lightning rod in the world"
PhraSed in another way, science now knows
that the other nearby skyscrapers are protected
against lightning by their huge neighbor
Let us now see what DR.. H. L. Dryden, chief
Of the Bureau Of Standards aerodynamic sec
ton and in charge Of the unique Federal test
program, says about the results obtained:
When the Empire State Building was con-
structed, provision was made through the CO.
operation Of architects, engineers and owners
to have the building serve as a laboratory for
obtaining q more accurate knowledge of wind
pressure. Under the direction of the Commit
tee on Research Of the American Institute Of
Steel Construction, 80 devices known as pres
sure outlets were installed on the thirty SIXTH
fifty fifth and seventy-hft floors. These are
simply tiny pieces Of pipe, set flush with the
outside wall through which the wind blows
against a column Of liquid which registers pres
sure in q gauge.
Exactly the same principle is employed as is
the common practice in measuring air speed
In airplanes. These gadgets, in other words,
afford handy readings Of wind pressures on the
building at all times; and it may be Of interest
to know that similar devices were employed on
our models during the wind test program at
the Bureau of Standards.
In addition, some Of the steel columns under
the tower portion of the Empire State Building
on the twenty nth floor were provided with
strain gauges for determining strains in the
columns due to wind. instruments for meas
uring the direction and velocity Of the wind
we're mounted ON the top Of the structure.
HE forecastng Of the wind pressure to be
expected on . building has many Of the
aspects of q game Of chance. 1t is practically
certain that the speed Of the wind will exceed