The Montgomery advertiser. [volume] (Montgomery, Ala.) 1885-1982, 1904-07-03

thus created that with a stretching or
contraction of one ten-thousandth OF
an inch in the concrete beam the ray
of light traverses a space of three
inches on the indicator. The most min
ute changes in the material are thus
recorded. A mere nothing faint
football or an automobile passing in
the next street-serves to set the light
beam CHANGING up and down the scale
of the Indicator. On account of its del
icacy the hours from midnight until. 2
or in the morning are most valuable
for observations.
The importance of such Investigations
as these which are being conducted
can be fully understood only by en-
gineers and by those familiar with the
extent to which concrete is now used.
and the still greater extent to which
IL Is likely to be used in all building
operations of the future. This has been
called the age of Portland cement
Probably all engineering experts be-
lieve that concrete will very shortly
displace timber the worlds most
important constructive material In
deed. most of the more modern cities
of Europe-such as those of the Ger
man empire which have grown very
rapidly in the past three decades-have
been for the most part built of con-
crete. Statistics show that the mater
ial is as yet much more important in
dustrially abroad than in the United
States In 1900 this country made about
s. 100000 barrels. England alone. a
much smaller country. manufactured
about 100000 barrels and Germany
shows a yearly output of more than
90, 000, 900 barrels.
Everybody has known for long
time that concrete is used for side
walks and foundations of buildings
We all have seen 1t in our cellars. But
| the man in the street has hardly yet
begun to realize what enormous guam
| titles of it are employed by the rail-
roads for bridge piers and culverts
and even for ties and fence posts. Its
usefulness is increasing every day. In
at least one very notable sky scraper
| in the construction of an Office build
| ing 210 feet high. in Cincinnati. prac-
| tically the only material employed is
concrete, reinforced with twisted rods
| of steel which serve to take up the
tensile strain, the concrete being de-
| signed to resist only the strains of
compression. Again a very striking IL
lustration of the employment of the
! up-to- date material is found in the
new subway which the Metropolitan
Railway of Kansas City has just COM
| pleted. Here we have a tunnel $50 feet
| long which was originally built of
brick, with an arched roof and which
would have still been serviceable had
| 1t not become necessary for the engin-
| GERS to change its grade when they
abandoned the old-fashioned cable
cars. Brick has been abandoned in
| all the new parts of the subway and
concrete construction has been sub
| stituted with the so-called nat arched
| roof. This roof is from Is inches to
| . feet thick and is reinforced by inch
| square steel bars and smaller bars en-
| bedded in the walls to give them addi-
tional strength, the whole work involv-
ing about 5000 cubic yards of concrete
| and 300 tons of steel
| Considering the immensely of such
industrial operations 1t becomes ap-
! ties of the various grades of concrete
which are put on the market are un-
| derstood by the engineers the safer the
| ordinary man may feel in his daily life
! When concrete was used mainly for
| fagstones questions regarding its
| breaking strength were of no great
moment but when you find a 20-story
skyscraper built almost entirely of CON
crete beams. then the necessity for ac-
curate knowledge becomes evident.
| The various kinds of concrete upon
which technology experts will be at
work this summer differ naturally
enough in their composition. according
to the formulate used by the manufac-
turers. The foundation of all cement is
limestone, with certain proportion of