Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1889-01-18

ticularly has almost cohesive or sensie |
| strength until it has become tolerably dry and |
until nearly dry it has but feeble resistance
| TO cffer to strains of compression. When fully |
| dried-as 1t may be i'll an ordinary wall after |
the lapse of six months-the crushing strength |
Of lime mortar ranges between $50 pounds to |
tons per square foot. How could the mortar |
| have dried during the short period the Wiley |
building was being erected?
| 'Too Much Haste.
| Even in the driest summer weather such |
rapid work would hardly have been considered |
| safe by conscientious and intelligent in |
spector of masonry. 1t is certain the inspector |
would have all the authorities to side with his |
| views Here we have the lower courses of |
mortar joints, while still green, subjected to |
| load of four tons per square foot, or to per- |
haps half, or certainly to Jne-quarter OF their |
ultimate strength, which we may assume |
would have been reached in six months. To |
have been even tolerably safe, eight or ten
weeks at least should have been occupied in
constructing brick walls of that height, and in
winter such as we experiencing, even
longer time would be advisable.
| A common remark among observers at the |
scene Immediately after the accident was that
| the mortar appeared to have too much sand In
] it. This was a natural conclusion, but probably
| an erroneous one, and unjust to the contractor
! The chemists analysis shows, and close ex-
animation of specimens of the mortar would
indicate, that there was suficiency OF lime:
| The chemist says the proportion was as one OF
lime to four of sand which represents the aver
| age mixture. One lime to five sand will make
| good mortar. according to some of the authorl-
ties. In quality, also, the lime was probably
| good. The sandy appearance OF the mortar is
| due to the crushing load 1t was prematurely
| called upon to bear, and not. as some have
| thought, to the absence of the proper proper
ton of lime. or, as others have said. to frost
| killing" There has not been enough frost this
| winter to more than freeze the exposed surface.
| But mortar, even slightly crumbled from what
ever cause, when partially dried will never aft
erward make good bond; and it Is, therefore,
more than probable that the Wiley building
| never would have had durable walls. The ac-
ton OF frost and rain would have rapidly dlsln-
| tegrated the joints, though the building, so
long as the walls remained vertical, might have
stood many years, as numerous other ram
shackle" structures are standing throughout
the city.
The Force of the Wind.
On Wednesday, the 9th inst, there was a
wind storm which by 1885 P. IL developed into
gale attended with local swirls and puffs of
wind of considerable violence. The general
direction of the winds was from the southwest, |
and at the hour and minute named one of these
sudden squalls struck the Wiley building. The
front of the building facing on Diamond street
was open, that is to say the sides and rear walls
had been completed to the top line of the sew
enth story, but the 'front.' from the ground up,
remained to be put in. The open front and
sac for the force of the wind to operate in.
The rear wall of the Germania Bank building
served further to defect and concentrate the
wind on the devoted structure. 1t was an ex-
traordinary and remarkably sudden squall for
Pittsburg, but would have occas1oned slight
comment in some of the seaboard cities, or even
in Dakota. 1t so happens that at the United
States Signal office, located almost directly on
the track of this miscalled tornado and scarcely
more than 200 yards northeast of the Willie
building, the thermometer registered the ve-
locity of the wind. The actual force of the
wind at the Wiley buildingicould scarcely have
been made greater than 1t was at the Signal
office. The greatest recorded velocity of the
wind was 40 miles an hour, and this was at the
time the building fell, though for reasons else
where assigned the force eXerted by this wind
at the Wiley building may have been greater
than its velocity, as recorded 200 yards distant
would appear to indicate. Nevertheless, this
is case where actual observations were taken
of the force of the wind and as near to the
scene of a disaster as rarely has happened since
the United States Signal Service was estab-
lished.
Remarkable Fact.
The rear of a new, not yet furnished, eight
story building was within 200 feet of the Wiley
structure. Its windows facing the direction
from which the storm came were temporarily
closed with common cotton sheeting, and yet
few of these sheets were torn or blown in. The
fact that they were not all torn out is of itself
remarkable-so also the fact that no other
buildings or chimney tops in the vicinity were
carried away is equally astonishing. This is
not the way of tornadoes, and far less the way
of gales. viz: to pounce down upon single
isolated spot. Tornadoes often lift or bound
over number of buildings, or other apparent
distractions; still they leave a we'll defined
track, broken. though it may be in some cases,
with gaps where little or no damage is done.
Not SO in this case; southwest and northeast
course laid over the Wiley building will show
no more damage to trees, fences, ETC., than was
experienced in other parts OF the city and ad- ,
jacent country. Nevertheless this particular
hnldinU down |
of it." I
We can only surmise what the pressure ex-
erted by the winds within the walls actually
was. Rouse & Smeaton's formula gives for a
velocity of 40 miles an hour pressure of 7.S
pounds per square foot, Considerable uncer-
tainty exists, however, as to the application of :
the formula, for much depends on the shape
of the object presented TO the wind angle of
incidence, etc. 1t is known. however, that I
concave surface offers greater resistance than S
an equal section of plain surface and con-
vex less. That the Wiley building received
the full force of the storm there can be no +
doubt. 1t was cOncavity, into which also e
the GermaEia building very likely DETECTED a
further increasement of wind force. We
might assume that the combined forces oper- =
ating developed power equaled by gale of
so miles per hour and that its force was ac-
cordingly 123 pounds per square foot. V
blow down brct is vail TI Tbpp WieU
building walls were, 1t is said, q inches for the
first story, though several of the upper stories
were only l3 inches thick For five stories
such walls would be deemed safe, for six they
are light, but for seven stories they are de- y
cidedly unsafe for buildings intended for gen. n
eral business and storage purposes.
-
What Caused the Crash.
Nevertheless, if the wind, which lasted f
scarcely more than two minutes was the cause
of the accident, its effect if the walls had been
dry would have been confined solely to the :.
upper story, or perhaps, the upper two stories. =
and it is well to note hero that surrounding
%I.r
ries from the direct violence of the gale. 1t is
not an infrequent event for light top stories of p
buildings to be blown off, for it is at the top II
where the winds usually have the fullest
sweep, and there is the least thickness of wall n
and dead weight to resist its force. But an eye .
witness. the intelligent carpenter, who saw the u
Wiley building fall, from window of the Ger c.
mania building, says it fell altogether in one
mass. 1t was one grand crash and the entire | 49,
seven stories were leveled to within few feet =.
of the earth, the upper part OF the walls falling VI
outwardly and the lower part falling more or II
less uniformly 1nwardly. How then can we ac-
count for the accident? :,
In the first place We must consider that the y
walls were green; and as we have sought to y
show, the mortar joints in some parts were 81
crushed or crumbled, Eand lacking in bond in
consequence of that fact Higher up, where ir
not much weight rested on the walls the hori- =
zontal Joints were thoroughly soft fresh-laid "
mortar. Under the circumstances it is posi- CT
lively certain that at no part were the walls set
and rigid, while the contrary, there is every o.
reason to conceive of them as being flexible {"
The heavy wind pressure acting expanslvely in III
the interior of the bulding-say from the third C;
floor to the seventh, and greatest near the top
where it overfiowed-tended to bend the walls ",
by relieving the inside bed-joints of mortar of "
some of the weight and increasing the COM d
preston correspond1ngly on the outside joints Of
The mortar even half way down had two tons is
weight to the square foot of wall pressure upon fl
it to start with, the further strain on the out
side joints caused by the leverage of the
walls completed the task of pulverizing CT
the mortar on that side. A very little ST
Texture of the walls that far down would g,
cause the top portions to lean over its center Of
gravity, and thus cause them to topple over: =
The radius of the swing of the top portion Of o
tile walls was, toward the Wood street side, =