The Lambertville record. [volume] (Lambertville, N.J.) 1872-1968, 1882-03-22
GREAT WIND STORMS.
Characteristics OF Tarnatioes--Their Re.
mnrlsnble Effects.


The american Asckitect gives the results
of an elaborate inquiry into the characters.
tics and effects of tornadoes, instituted with
the object of finding if anything might be
done to bring about better mode of build
ing thus ayerting much of the injury now
done. The replies, which are chiefly from
various parts of the Western States, convey
the impression that the force of tornadoes
is irresistible aud not to be avoided. II
seems to be agreed that it would be hardly
practicable to construct tornado-proof
building, although round or dome-shaped
building, without any projections, might re-
sist the force of the wind II is now COM
mon, in the tornado-infested states of the
West for farmers to construct an under
ground refuge near their houses, where they
can shelter themselves in case Of the APP
proach of tornado. General w. B. Hazen,
the chief signal officer of the United States,
contributed some valuable statistics on the
sss'es~cs. ssrnsSaerinf, -sesoeiky.
force of the wind, he says that, from the de-
struction of brick buildings, wind pressures
of from IS TO 81 pounds square foot have
been demonstrated, while from the lifting
Up, transportation and destruction of loose
objects, such as barrel of tar, locomo-
tive, stove, heavy log cattle, wind press
ures of 80, %, 81, 1f2 and IS to SO pounds
i square foot respectively, have been dem
onstroted. The upward pressures are shown
10 be occasionally as great, il not greater,
tha hpp o,1l
locities of 60 metres q second, 1876 miles an
hour, Judging by tho effect produced, are
not unusual. The ancmometer has register.
ed horizontal wind gclocities of so miles an
hour (subject to reduction to about SO miles
al hour for possible instrumental errors)
during tornadoes, but, as velocities of $50
miles an hour (140 reduced MS before) have
been recorded in hurricanes, there seems to
be no reason why the Same should not be
attained in torn loes. 1t has been shown
that the area exposed to destructive wind
velocities such as have been instaneed is
very small, not greater than 10, 20 or 100
fee. square. This has been shown by the
narowness of the path of greatest destruc-
tveness in tho track of tornado. In the
different portions of this area of maximum
severity tho winds are blowing ut the same
time from different and perhaps even oppo-
site, directions, so TINT the total resultant is
not so much to overtum, carry off on crush
in rs TO twist an object around vertical
axis. General IIazen says that as tho cen.
trail area on maximum intensity is compare
lively narrow--and the chances are very
small that a building will be exposed to the
yiolen! twisting ac,.on-it is evident thai
the average velocity of rectilinear winds
within the general path of moderate de-
struction is the one most necessary to be
provided against in orlinai, structures.
These winds may attain velocity of eighty
miles an hour over an area 1000 feet broad,
and generally blow from tho southwest;
those next in frequency blow from the north
west. The duration of these destructive
winds varies from six to sixty seconds, and
the general averpge Of inxge ssaanper OF
cases is sixteen seconds. A building exposed
10 these winds experiences but one stroke,
like the blow Of a hammer, and the destruc-
ton is done. In the case, therefore, of q
suspension bridge, chimney, or other
structure liable to be set into system of
rythmic vibrations destructive to its integ-
rity, the effect of the maximum winds in in
ducing such vibrations is reduced to mini
mum. The duration of the heavy southwest
and northwest winds prevailing over the
area of moderate destruction rarely exceeds
two minutes.