The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1895-10-06
MOVEMENTS OF A FALL TOWER.
Tests Made from the Perch of the
William Penn Statue.
Philadelphia Record

Since last Sunday, when a slight earth
quake disturbed the early morning medita-
tons of pious Philadelphians, there has
been not a little discussion regarding the
stability of the tall tower on the big and
costly City Hall. The great structure of
pearance TO observers 500 feet below on the
sidewalk. and the fear was expressed that
the heroic effigy of William Penn might
have been so shake as to render his ele-
waited position insecure People who knew
how to go about getting Information anent
the public buildings could easily have had
their fears set at rest, for one OF the in
teresting appurtenances of the tower is the
crude s-eismometer, which carefully regis
tiers every little variation TO which the
tower may be subjected.
Directly beneath William Penn a fine
piano wire is fastened which extends
straight down for nearly three hundred
feet. A plumb-bob Weighing twelve pounds
Is attached to the end and lies submerged
in about ten gallons of mcIasses. If from
any cause whatever William Penn should
he Subjected to q iopple. his antics would
be revealed to the men who placed him
there by the plumb-bob in the molasses.
This contrivance is on the seventh floor
of the tower, directly behind the elevator.
A high iron railing surrounds an unimpor-
tant-looking wooden box, and the visitor
has to look twice TO see the wire leading
up from the box. The wire descends into a
square frame, and by laying a ruler care
fully next the wire the calculator can de-
termine whether or not the statue. and
hence the tower, Is stul In It's orlglnal po-
sition-
As a matter of fact-and this will not
please those individuals who in their night
clothes sought the safety of the street last
Sunday ~morning-the City Hall tower did
not experience any cslculable vibration dur
ing the earthquake. The shock became in
fnitesimal before 1t reached the roof of
the City Hall, and as for William Penn. sit
never touched him" However. investiga-
ton has conclusively proved that the statue
does move, and in the proper weather its
movement amounts to as much as a quarter
of an inch per dav. At Z, IL and 3 o'clock
each day the superintendent of the tower,
or his assistant, lays the rule by the wire
and notes the changes.
To one unacquainted with the possibili-
ties of engineering the tenacity with which
William Penn maintains his perfect equi-
lsbrium Is marvellous. The uninitiated have
no idea OF the difficulties to be met and of
the exact perpendicular. The massive iron
and stone work has been so nicely con-
structed that the assaults OF wind. hail.
snow or rain avail nothing. Some Slight
oscillation occurs. but IL is trlhing. and
when the bob is still again the average of
its movements is always zero. which means
that the tower is perfectly plumb.
The one force which Is bound TO have it's
little fling is the sun. Heat expands and
cold contracts, despite the ingenuity of
man. At I o'clock in the morning the line
is always in the center OF the square. The
action OF the sun on one-half of the tower.
when the OPPOSITE half is I'm the shade.
causes n barely perceptible tip. The stone
work expands slightly under the action or