The morning news. [volume] (Savannah, Ga.) 1887-1900, 1896-12-15
STRENGTH TESTING MACHINES.
The Most Dangerous Tests Are Thosq
Made on Blocks of stone.
From the Boston TRANSCRIPT

From the Boston Transcript.
One of the most interesting places in the
city of Boston to one of mechanical turn
Of mind is the engineering building Of
the Massachusetts Institute of Technology
and especially that part of 1t where the
tests of the strength of different materials
are made. The testing plant is one of the
best of its kind in the country, and the
test of the strength of about anything
from Irvine to iron columns, ETC., can be
made. 1t is not generally known, but il
is fact that it was at this plant shat
the first tests of large beams, columns,
etc. cor buildings were made, and as a re-
suit Of the discoveries which were male
by these tests the building laws all over
the orld were changed.
The most interesting discoveries were
made with regard to the strength o.
wooden beams Previous TO these tcs
the strength of beams had been figurei
by testing small pieces of the same kim
OF wood and then calculating the strength
of the beam from the strength shown by
these small sections. In making these
calculations the small pieces which were
test ed we're taken perfectly clear and fl zee
of knots. and allowance was made far
the weakening of the beams by the IN.
perfecuons in them. AS a result of the
tests mace at the institute on entire beams
1t was shown that this allowance was
not nearly large enough, and that fol
some time beams had been figured on to
carry leads which would bring them dan
gerously rear their breaking point
The most imposing figure in the testing
plant at present is the big machine which
is used for crushing and tensile tests The
machine is an Emery patent and is on Just
the same principle as the one at the Wa
tertown arsenal, although it is not SO DOW
erful, the latter being the biggest in the
world The Institutes machine has a
strength of only 300, 900 pounds, but this
is enough for any tests which are made
there, and, in fact. for the large majority
of the tests which are made at the arsenal.
This machine will crush a great iron col
umn together endwise in its powerful grasp
or will pull it apart as a confectioner pulls
molasses candy.
More spectacular than such tests as these
are those made on wood beams, when the
great timbers after resisting to their ut
most, bend upward and then break with
a tremendous rending crash. The most
dangerous tests are those made on blocks
of stone, granite especially. A block of
granite will resist almost to it's breaking
point without giving any sign, and when
it goes it goes with report like a small
cannon, and is reduced almost to powder
The small fragments fly with tremendous
velocity, and 1t is necessary in making a
test of this kind to cover the object with
thick layers of cloth, to prevent the wound
ing of the students.
over in the corner OF the basement is
the tortion machine. one of the most In
teresting in the whole plant. It is pow
erful enough TO twist a three-inch bar
of the finest wrought steel an unlimited
number of times. 1T is surprising the ex-
tent to which bar of good material
will twist before breaking. There are at
the institute some bars of Norway iron
which have been twisted round and round
twenty times in a length Of six feet, and
tho pitch is as even as though II had been
cut with a machine. Domestic iron. on the
contrary, will stand hardly any twist
without breaking. The means by which
the twist Is manifested is rema rkably in
teresting. Two telescopes are mounted
on the bar before the twisting process ls
begun, and these are sighted on a Rradu-
ated scale on the wall across on the other
side Of the shop. and by this means tho
slightest movement OF the bar can he
read with the greatest distnctness II
seems almost incredible, but It is possible
for man to take hold Of the bar whom Il
has been clamped into the machine. and
by twisting II with one hand to produce
movement which is discernible on the
scale on the wall