New-York tribune., 1909-05-02
BIG TESTING MACHINE
Bridges Can BE Made -4bS0LuteIu
Safe by It's Use.
From Tie Tribune Bureau !

Washington April A.-Engtneering in this coun-
try though having reached a high state of eff
ciency and rvalling that OF all other countries In
the world for the wonderful progress made in the
last century, has been minus a most important
machine, and the erection Of such a machine by
the United States Geological Survey in Pittsbure-
for testing the strength Of structural materials
brings to light grave lack of knowledge on the
part of engineers 1t has been the practice Of engf
neering experts TO allow e certain amount of
weight 70 a prescribed sized beam, and in cases
where beams twice that size used engineers
have figured that they should carry twice as much
weight the single one. Here is where they have
erred. The Quebec bridge disaster demonstrated
this fact Not many months ago. through lack Of
knowledge concerning the strength Of great col
uHns used In such structures. too much weight was
allowed to bear the bridge supports and as
result the bridge collapsed, causing the death OF
eighty persons and adding thousands of dollars 10
the loss column This Is one of the many instances
which might be cited where the need of moro ex-
pert engineering knowledge has been found to be
absolute necessity for safety in erecting large
structures.
The new machine. which is being built at the
Geological Survey testing station in Pittsburg is
the largest testing machine in the world, weighing
more than hundred tons. 1t towers IN the air
70 a height OF eighty feet above the foundations.
and exerts maximum pressure OF million
pounds which is equivalent to placing load Of
i've thousand tons on the beam column TO be
tested. It was made for the survey by TinIus
Often of Philadelphia
with the introduction OF this machine the ersf-
ueering world finds itself advanced one step nearer
70 the erection OF large structures without fear OF
their tunbling down because of too much pressure
on the supports This machine not built with
the idea OF testing steel columns only, but large
blocks OF stone and columns of concrete and brick
well The survey took the matter up not only
for the public generally, but for the OF the
supervising architect OF the government and his
large force OF assistants who make plans for pub
lie buildings representing a yearly outlay of from
E20Oo0oo to a5,co4.0Oo
Joseph A Holmes, expert IN charge Of the tech
nologic branch of the Geological Survey, who is
supervise the Investigations says that the testing
in this machine Of the stone concrete and brick
columns will determine the relative safety, adapta-
biiity and durability OF those materials, and how
the quantity of each material used may be safely
diminished. thus reducing the cost of the con-
struction work In the past it has been necessary
TO determine the strength Of large columns the
assumption of the values obtained from testing
smaller columns In the Of stone, the small
pieces tested were without the usual quarried ef-
fects and seams which are to be found in large
pieces of stone and such tests as have been made
show that the strength OF the stone decreases as
the size OF the stone increases In the erection Of
large buildings the strength Of these columns be-
very important matter, and IL is absolutely
necessary that there be accurate data as to the
strength which may be expected from these ma
terials when used in larger masses.
In the rapid development OF this country the
enormous locomotives OF constantly increasing size
and the heavier tonnage have demanded
increase IN the size OF bridges, with built
up structural members Of such size that We have
been unable TO keep pace with experimental data
serve 6 guide for such structures. AS a
result to-day have practically knowledge
Of the strength of these structures from actual
tests. and must base information on the tests
OF very much smaller members. Bridges such as
that which collapsed at Quebec. composed OF
number OF members held together by riveted con-
nections, depend largely the design and work
n1snship and this failure has demonstrated that
Il absolutely necessary that tests OF large sized
members be made that the engineer may know
10 what extent the built-up structure Is affected
by the workmanship; that he may know what
strength 10 allow for these riveted connections
There is machine in the world that could test
z chord Of the size that which failed in the
Quebec bridge at the present time, or Of the size
OF the recently completed BlackweHs Island Bridge
machine OF the capacity which va building