Marietta daily leader. (Marietta, Ohio) 1895-1906, 1897-08-21

out of balance. Moreover. remember
ing our first column of checkers. 1t is
clear that such an accident 0 a column
is more likely to happen near the top
of building than near the bottom. But
If cast-iron column is fractured or
displaced in one of the upper stories @ "a
tall building it will crush through its
floor, and, with the added weight of its
destruction, fall through the next floor.
gathering momentum as it goes. until.
in three or four stories, it will have
gained force enough to tear the whole
structure to pieces.
The regular, modern steel cage acts
more like japanese temple, because
it's component pieces are not liable to
fracture and also because they are so
riveted and bound together as to form
unit to any force trying to overturn
them. 1t is very probable that the ef-
feet Of a moderate earthquake on. a
building of this kind would be to shake
the walls out of their panels, leaving
the people within standing safely on
their floor, like q dolls house with the
front open. Theoretically, in order to
capsize one Of these buildings, it would
be necessary to apply q force to ii
which would bring its center of gravi-
ty from line drawn down through the
center of the building to point corre-
spending to one of the outer walls.
Thus an earthquake wave attacking II
steel cage building 100 feet long by 100
feet high and 80 feet in width would
have to act across the width cf the
building so as to move the center of
gravity, which would be approximately
40 feet from the ground. 16 feet. As
sulning the weight of such building.
at 1.3G tons to the square foot, to be
5000 tons, it would take force of $500
tons acting for one second on one edge
OF its 100 feet length to turn it over.
This seems a coed dea., but the
pressure of the Neapoiitan earthquake
in 1857 was calculated by Mallet to be
equal to G5,252 tons Of 2.240 pounds for
100 square feet. so that even if we
reckon its duration at one-third of a
second there was nearly nine times as
pitch over a building of the size and
weight just given.
If earthquakes were not so capricious
|
might be derived from the fact that
they act differently on different foun-
dations. It would appear natural to
suppose that tail buildings resting on
rock, as most of those in New York do,
would be worse off than those resting
on piles on an earth foundation. as is
the case with all the tall buildings in
Chicago. The cushion of earth. in the
latter case, ought by analogy to deadeN
the force of the wave. But, alas! for
theories when the facts are otherwise
In the Lisbon earthquake of 1855, al
the houses whose foundation was on
clay were destroyed, while those buib
on limestone remained unhurt. In the
great Jamaica earthquake of 1862, the
houses built on limestone foundation
stood. while these on sand or grave
foundations were leveled to the ground
In the great Mesgina earthquake, the
houses which stood on alluvial founda
tions, like those of Chicago, were de
stroyed, while the rocks were again thu
place of safety.
The earthquake professors, or seis
mologists as they are called, have de
dided, after much thinking. that al
houses ought to be built on ball-bearin.
foundations to be ready for the shocl
when it comes. Perhaps the architect
of tai buildings will be forced to adop
this practice after we have had a feV
earthquakes to test our sky-scTapers
L. H, MJTLIIN