Catoctin clarion., 1911-05-25
the Cement ERA.

[The following item is taken from the
Scientific American. Otheritems on the
subject will follow.]
1t seems to be generally agree, and
we think with much reason, that the
year 1911 should mark the centenary
of cement, or, to speak more strictly
of Portland cement This selection
is due to the fact that Joseph Apsdin
was born in 1911, and that it is to
his intelligence and patince that we
owe our modern hydraulic cement.
History fails to establish the exact
date Of the first production and use
of this great modern material of con-
struction, for it is fact that Apsdin
who was a brickmaker in Leeds,
Yorkshire, spent a dozen years or
more in experimental work before he
covered his invention with patent,
and nearly three times that period
elapsed before his discovery received
its adequate recognition. incidentally
it may be mentioned that the invent
or gave to the new cement the name
of Portland, because it resembled a
building stone very widely used in
England, which is obtained from the
the limestone quarries at the Isle of
Portland, in Dorsetshire. The isle, "
by the way, is not an island, but a
rocky peninsula, extending into the
English Channel and connected to
the mainland by long, curving
beach.
1t has long been the habit of the
historian when speaking of the con-
structional or mechanical side of
human progress to name its various
eras after the predominant materials
of construction. Hence, in their
succession, we have had eras of stone,
bronze, iron, and steel. To-day we
find ourselves well launched in what
may Justly be called the era of cement.
Let it be cleary understood, just
here, that cement is many centuries
older than Joseph Apsdid's Portland
cement. Long before the Christian
era, the Egyptian and the Roman
builders were familiar with a form
of concrete, compounded from certain
natural lines, clays, and rocks (gcn-
orally volcanic) or gravel. Those
wonderful edgineer. architects, the
Romans, laid it freely in the found
ations of their temples, and did not
hesitate to make bold use of it both
in dome and arch. The concrete of
the ancients, however, was of slow,
ly-setting nature, requiring consider
able time to reach the great hardness
which characterizes such of it as still
survives.
The valuable quality of Apsdin's
invention lay in the fact that he
produced a mechanical mixture
which, when treated with the proper
amount Of water, will harden in a
short space of time, either in air or
water; and although his discovery did
not receive its due recognition until
the middle of the nineteenth century,
this wonderful method of making an
artificial stone, compounded of simple
easily obtainable and cheap ingred-
tents, was clearly set forth. Sub
sequently, the cement industry
awaited the development of another
great industrial art. that of steel
making, which was destined to place
it in its present position as the great
est of the worlds constructive mater
ials for works of magnitude.
For all uses to which ordinary
masonry can be put, cement, when
mixed in the proper proportions with
sand and broken stone gravel, for
ms an admirable and, if properly
finished, a not unsightly building
material. But like any other system
of masonry construction, while it is
capable of enduring heavy strains of
a compressive nature, il is illadaptcd
for those of tension. Hence concrete
necessarily has very limited range
of use in structures in which heavy
tensional and bending stresses will
occur, as, for instance, in beams or
girders, in arches of fiat span subject
ed to uneven loading, or in posts or
columns where structural require
ments call for small ratio of diam
eter to length.
About the time that concrete was
beginning to receive its due recognition