THE ROMANCE OF CONCRETE
THE ONE-PIECE HOUSE OF THOMAS A. EDISON, AND OTHER USES OF THE
NEWEST AND YET THE OLDEST BUILDING MATERIAL OF CIVILIZED PEOPLES
SEEN BY THE BOY AND HIS SCIENTIFIC FRIEND
While we are looking around at all these epoch-making inventions let
us follow our friendly scientist and his boy companion to one of
the big cement shows held in the various large cities of the United
States every year, for a glance at some of the uses of reinforced
concrete in modern engineering and building. For the boy who intends
to become a civil engineer this wonderful material will have an
especial interest, because its successful use in all of the greatest
engineering works going on to-day has brought it to the front as
the modern substitute, in a great many cases, for wood, brick, or
expensive stone and steel structures.
[Illustration: WHAT ONE SET OF BOYS DID WITH CONCRETE
This Indian tepee of concrete was made by the boys of Dr. W. A.
Keyes' summer school, at Sebasco, Maine.
The picture on the left shows the method of construction.]
[Illustration: MASSIVE CONCRETE WORK
Completed side walls of solid concrete in the Gatun Locks of the
Panama Canal.]
[Illustration: A LEVEL STRETCH OF CATSKILL AQUEDUCT
Showing completed section as well as forms for the concrete.]
On entering the cement show our friends saw on every side long rows
of booths showing models of structures and articles that could
be made of concrete. There were models of houses, subways, dams,
bridges, dock works, retaining walls, sewers, bridges, pavements
and even boats and furniture. In fact, so the men in the exhibition
booths said, concrete can be used for practically every building
purpose where strength, lasting qualities, and resistance to heat and
cold are needed. "This is the concrete age," they declared. "Concrete
is fireproof, waterproof, sanitary, and resists frost when properly
used. Our timber supply is decreasing, the supply of iron ore for
structural steel is limited, and stone is expensive; so concrete,
reinforced with steel, and used by engineers who understand their
business, will be the greatest building material of the future."
These are the things that the enthusiasts at all the concrete shows
say, but they admit that there are certain kinds of construction in
which concrete is not as effective as steel or granite. Also they
say that the use of reinforced concrete requires the highest type of
engineering skill, and a complete understanding of the technicalities
of the subject.
One of the places where we know concrete best is in pavements and
sidewalks, and several of the booths exhibited samples of such work.
To show its strength the men in charge piled on weights, struck the
slabs with hammers, or subjected them to any kind of hard usage
suggested by the crowd. Then, too, there were sections of concrete
buildings, and exhibitions of various systems of reinforced concrete
construction. With these there were concrete chimneys, portable
concrete garages, railroad ties, and what not.
"Oh, but look here," broke out the boy as he led his older friend
about. "Here's a perfect model of a house."
"Yes," answered the man, "that is a model of the famous Edison poured
cement, or 'one-piece' house, the latest invention of our great
American inventor."
There the little building stood, perfect in every way, surrounded
by a model concrete wall, a beautiful lawn, and approached by fine
concrete walks and driveways.
"This model," explained the scientist, "represents what Thomas
A. Edison is trying to get time to accomplish for workingmen and
their families. Instead of being built piece by piece, the house is
supposed to be made all at one time by pouring the concrete into a
complete set of moulds. This house is so interesting that we shall
look at it much closer a little later on."
"And here," said the boy; "what's this?"
He had paused before a perfect model of the Gatun locks of the Panama
Canal, where the world's greatest work in concrete, or any other
kind of masonry, is being carried on. The work is greater than the
Pyramids of Egypt or the Great Wall of China. Though we will not
bother ourselves much with figures, it will give an idea of the
size of the job on the canal when we realize that it will require
8,000,000 cubic yards of concrete, and more then 900,000 tons of
Portland cement.
In all there will be six great locks for the transportation of our
ships from the Atlantic to the Pacific and back. Three of these locks
are at Gatun on the Atlantic side of the canal, one at Pedro Miguel,
and two at Miraflores. Each lock will be 1,000 feet long, 110 feet
wide, and 45 feet deep--and practically all of this is done with
concrete. So massive is most of the work that steel reinforcement
is only necessary in certain parts of the project. The problem of
sinking the great retaining walls to bedrock, and making them strong
enough to hold in the face of the tremendous floods of the Chagres
River, alone makes one of the most stupendous engineering works ever
undertaken by man. Were it not for the use of concrete the cost
of the work would be so great as to make it almost impossible of
accomplishment.
The model of the Gatun locks showed the boy everything, just as it
will be when the canal is opened for traffic in 1913. There was the
wide Gatun lake, surrounded by the tropical forests, the great Gatun
dam, and the series of locks in one solid mass of concrete. These
locks when completed will be 3,800 feet long, and their tremendous
height and thickness can be seen from the pictures of the work as it
is actually being carried on. In the model there were perfect little
ships on the lake and going through the locks.
Besides the many present day uses of cement some of the concrete
enthusiasts are suggesting that heavily reinforced concrete be used
in place of steel in making bank vaults, as they declare that the
material will resist the keen tools and the powerful explosives of
bank robbers even more successfully than the hardest steel.
Then too, at the cement show, the boy saw, besides models of big
works and examples of all kinds of concrete construction, exhibits of
the various methods of placing steel bars and steel network in the
cement to make it stronger, and the different machines used in mixing
concrete and in making Portland cement, which is the binding element
in concrete.
As concrete is a material that can be mixed by an amateur and used
for a great many purposes, the booths where mixing and simple uses
were demonstrated attracted a great deal of attention. For instance,
in the last few years the farmers have found out that they can make
watering troughs, drains, floors for stables, hen houses, and even
fence posts, of concrete just as easily as they can of wood or iron.
Moreover, the articles thus made will last practically forever. All
that is needed is a supply of Portland cement, and a little careful
study as to the best way of mixing it with the proper amounts of sand
and gravel. The amateur has best results if he starts modestly and
takes up the use of reinforced concrete after learning how to use
the material in its simple form.
One of the most interesting uses of reinforced concrete for the
amateur who has learned something of the craft is in making a good,
seaworthy rowboat, or even a small motor boat. Poured boats are
strong, graceful, and durable. If they are properly made there never
is any danger of their leaking, and by a little extra pains it is
possible to make them with air-tight compartments so that they are
non-sinkable.
The usual method of making concrete boats is very simple. The kind of
boat to be duplicated is borrowed and hung on the shore so that it
swings free of the ground. Then a mould of clay is built all around
it. A strong bank of sand is heaped around the clay, to hold it firm.
Then the boat is worked a little each way so that a space of about an
inch and a half is left all around between the outside of the boat
and the clay. The space between the boat and the clay is the space
into which the concrete is poured for sides and bottom after the
reinforcing rods have been properly inserted. After the whole thing
has stood a day or so the inside boat is taken out and the clay mould
broken down, revealing a complete concrete hull.
Thus, we see that concrete can be used as a building material in
practically any kind of construction, that it is easily handled
since all that is necessary is to pour it into the moulds after the
engineers have properly placed the reinforcement, and that it can be
cast in practically any decorative design just as easily as plain.
Add to this the fact that concrete is cheaper than stone or steel,
and that it is practically indestructible when properly handled, and
it is easy to see the reason for calling this the cement age, and
concrete _the_ building material of the future.
After the Panama Canal, the greatest engineering feat in which
concrete figures as one of the chief materials used, is the Catskill
aqueduct, by which water from four watersheds in the Catskill
Mountains of New York State is to be piped to all five boroughs of
New York City. The Ashokan reservoir, near Kensington, N. Y., was
the first part of the work to be taken up, together with the Kensico
storage reservoir twenty-five miles from New York, several smaller
reservoirs, and the aqueducts to carry this water from the mountains
to every home in greater New York. The dam and containing walls of
the Ashokan reservoir are all made of reinforced concrete, and the
size of the lake and the strength of the walls can be appreciated
when one thinks that the 130,000,000,000 gallons of water it holds
in check would cover all Manhattan Island with twenty-eight feet of
water. A large part of the aqueduct proper, through which this great
stream of water is carried from the mountains, under the Hudson
River, and to the city where it runs more than a hundred feet below
the street level, is made of reinforced concrete.
For other examples of the use of this material in big engineering
works a boy has only to look around him. There are the tunnels under
the rivers around New York, the New York subways, the Philadelphia
and Boston subways, the Detroit River tunnel, bridges, culverts, big
piers and other dock works, miles of concrete snowsheds along the
lines of the railroads that cross the continental divide of the Rocky
Mountains, and in fact practically every big structural undertaking.
Almost anywhere we look these days we see a big machine crushing
rock, mixing it with sand and mortar, and turning out concrete to be
shovelled into a hole and perhaps used far below the surface by "sand
hogs" working under compressed air, or hoisted to the towering walls
of some great office building or factory that is being constructed of
the artificial stone.
We are familiar with the falsework of a concrete building under
construction. It is all, apparently, a maze of wooden beams that
look like scaffoldings, and yet they seem to make the outlines of
the building. This maze of woodwork, seemingly so lacking in plan or
system, as a matter of fact is a triumph of engineering skill, for it
is the mould for the building, and was all built by the most careful
plans as to strains, stresses, floor loads, etc.
First, however, before building the mould for a residence, school,
theatre, office building, or factory, the engineer decides what
strength his foundations must have. The foundation for a small
residence is an easy matter, but when it comes to a big factory, or
an office building of a dozen stories or so, the most careful work
must be done beforehand. In the old days, when it was desired to
sink the foundations of a building down to bedrock, they used steel
or wooden piles, but these will rust or rot, and the modern way is
to use concrete piles. Either the great poles are moulded first and
sunk like the ordinary wooden ones, or a pipe with a sharpened point
is sunk and the concrete deposited in it by buckets designed for the
purpose. Once these piles are driven, they are there for all time,
if the work is done properly, and the engineer can be sure that his
building is as good as if resting on bedrock.
From then on the erection of a reinforced concrete building is a
most intricate matter, because while concrete in itself is a very
simple substance, its use in buildings is a highly developed science.
Of course there are many different methods of using concrete,
and each one prescribes a different kind of steel network for
the reinforcement. Then, too, some engineers cast parts of their
buildings separately and put them in place after they have set, while
others run the concrete for beams, floors, and walls into moulds,
built right where those parts are to be in the finished structure.
In laying the steel reinforcing rods, before the concrete is poured,
the engineer sees that they make a perfect network so as to take
care of all the strains, just as they will be put upon the building
when it is completed. It is in the proper placing of reinforcement
that the greatest engineering knowledge is needed in this kind of
building.
As the wooden moulds for the first foundation beams and girders are
completed and the reinforcement is placed, the concrete is poured in.
The subcellar or cellar floor mould then is laid, the reinforcement
placed and the concrete run in. Next the moulds for the cellar walls
are built and perhaps the moulds for the beams and girders for the
first floor. The reinforcing rods are placed in these moulds and the
concrete run in, and so on, a story at a time, or a small section
at a time, until the structure reaches the height called for in
the plans, and it stands completed. As the building progresses and
the concrete on the lower floor sets, the moulds can be taken down
and used on higher stories. Concrete is even used for the roofs of
buildings, as it can be moulded right in place or set up in slabs
that can be later cemented together.
When properly used reinforced concrete is absolutely fireproof, so
it is coming into extensive use in the construction of schools,
theatres, warehouses, factories, and all other such buildings where a
great height is not required. So far, none of the great skyscrapers
has been built of reinforced concrete, although office buildings of
sixteen stories have been erected with complete success.
There is still another method of using concrete as a building
material. This is in the form of building blocks, and doubtless all
who read this will recall seeing many beautiful residences built of
blocks of stone that on closer inspection proved to be concrete. The
blocks can be cast in any size or form and used in just the same way
as structural stone.
Now, after having looked about the city and having seen the numerous
ways that concrete is used as a building material, we come back
to the very latest thing in the use of this man-made stone--the
"one-piece" or poured house.
For a good view of it let us take a little jaunt out to West Orange,
N. J., with the scientist and look into the library of Thomas A.
Edison's laboratory, where we will see a perfect model of this marvel
of invention. It is practically the same as the one at the cement
show. Standing in the centre of the great room where Edison works
is this perfect little cottage, about the size of a large doll's
house. It represents not only Edison's latest invention, but also his
favourite scheme. In years to come, when the boys who read this are
grown men, it will probably be no novelty to build houses by pouring
them all at once into a steel mould, but just at present it is one of
the most startling developments in an age of epoch-making inventions.
Every boy knows that Edison has never followed the ideas of others in
working out his inventions, and the poured house is no exception to
his rule. It will be interesting to take a little look back over a
part of Edison's life and see how he came to enter the cement-making
business, and how, when he had his process down to a fine point, he
said to himself, "It is cheap and easy to build a house or an office
building of concrete in sections, why not build it all in one piece?"
We shall see that no sooner had he asked himself this startling
question than he began by making models, and satisfied himself that
it was not only possible, but one of the cheapest and best methods
of making small, simply arranged houses, such as could be bought or
rented for a small sum.
Although Edison has within the last few years brought his idea to a
state where it can be put to practical use, he himself is not trying
to push it commercially, as he has his other great inventions like
the phonograph, storage battery, and the motion-picture machine. In
fact, he is content to let it be worked out by others just so long
as it fulfills his idea of giving to workingmen good houses at a low
price.
"Years ago, long before Edison had retired from active business
affairs to give his whole attention to scientific research," said the
scientist, as he and the boy walked about the laboratory, "he became
interested in metallurgy, just as he was and always is interested in
every other science where great difficulties must be overcome. In
those days iron and steel were not used as extensively as they are
now, but the scientists and leaders in the big industries saw that
the day was coming when far, far greater quantities of iron ore would
be needed to supply the great demand for steel to build skyscrapers,
ships, machinery, and so on. Men were going farther and farther away
in their search for iron ore, but Edison, with his never failing
originality, said to himself that it was likely there was plenty of
iron ore right around his laboratory in New Jersey if he only knew
how to get at it.
"For one thing," continued the boy's friend, "Edison had seen on
the ocean beaches great stretches of white sand with millions and
millions of little black particles sprinkled through them. He knew
that the specks were pure iron ore. You can prove this to yourself
by simply holding a good magnet close to a pile of such sand, and
watching the iron particles collect."
It was Edison's idea to concentrate the iron ore found in the earth,
in just this way, for he had sent out a corps of surveyors who had
reported vast quantities of low-grade ore in most of the Atlantic
Coast States. Low-grade ore is that which contains only a small
percentage of the metal desired, and hence it does not pay to smelt
it, unless a very cheap process can be found. Edison thought he had
a process cheap enough, for he simply intended to grind the mountains
to sand and take out the particles of iron by running it through a
hopper with a high-power magnet at the mouth.
The process sounds simple, but the machinery required was very
complicated, to say nothing of being extremely heavy. Edison set up
his mill in the mountains of New Jersey and started to blast down the
cliffs of low-grade ore and run them through a series of gigantic
crushers that ground them to a fine powder. The iron particles,
called concentrates, after being extricated were pressed into
briquets ready for delivery to the foundry.
After having spent close to $2,000,000 on the experiment, and
satisfactorily proving its mechanical success, the discovery of vast
quantities of high-grade ore in the Messaba range of Minnesota forced
Edison to close his plant. "This would have been a crushing failure
to most men," added the scientist, "but Edison's only comment was
a whimsical smile. Indeed, even on his way home after closing his
plant, Edison was planning new and more important activities, for
with his experience at rock crushing he was satisfied he could enter
the field as a maker of the building material called Portland cement."
At that time cement and concrete were even less used than were steel
and iron, but Edison for many years had seen that in the future they
would take the place of wood, stone, and brick.
"Well-made concrete, employing a high grade of Portland cement,"
said Edison on one occasion, "is the most lasting material known.
Practical confirmation of this statement may be found abundantly in
Italy at the present time, where many concrete structures exist, made
of old Roman cement, constructed more than a thousand years ago, and
are still in a good state of preservation.
"Concrete will last as long as granite and is far more resistant to
fire than any known stone."
But Edison had something more than a successful business in mind when
he returned from his rock-crushing plant, for he intended setting
up cement-making machinery such as had never before been seen. With
this end in view he began to read up on the subject, just as we have
seen the Wright brothers read up on aviation. Incidentally, as an
indication of the manner in which this wizard works, it may be said
that all this time Edison was perfecting his new storage battery.
One big improvement upon the usual process in the manufacture of
cement, planned by Edison, was that the grinding should be so fine
that 65 per cent. of the ground clinker should pass through a
200-mesh screen instead of only 75 per cent. as is the usual rule.
Thus, Edison made into cement 10 per cent. more material that other
manufacturers sent back to be ground over again.
The success of Edison's Portland cement plant is not matter for our
attention here, so we will pass over those busy years to the time of
Edison's retirement to devote all his time to scientific research.
For many years he had watched the cities grow, had seen the great
tenements become more crowded, and less comfortable each year. He
had seen the children playing in the streets, and had compared their
lives to the happy lives of the children whose parents could afford
to live away from the great cities, where boys could have yards to
play in. He decided that the boys of the city streets would have a
far better time, that their mothers and fathers would have a far more
cheerful life if they could live in comfortable little houses in the
country with yards, and gardens, and plenty of room for every one.
Edison saw that what was needed was a building material cheap enough,
and a method of using it cheap enough, so that dwellings could be put
up at a cost that would place them within the means of workingmen and
their families.
Concrete, he decided, was the material to solve the problem, and
Edison set himself to the task of making houses poured complete into
one mould so as to make the cost of labour as low as possible. The
"one-piece" house was an assured thing from that time on. All that
remained was for the "Wizard of Orange," as he is called, to work
out the difficult details of a properly mixed cement and a practical
system of moulds.
An incident that occurred at the time of the failure of his ore
crushing plant in the New Jersey mountains was one of the things that
brought the whole situation home to him. When the plant was closed
and the buildings vacated, the fire insurance companies cancelled the
policies, declaring that the moral risk was too great.
The inventor's reply was short and to the point. He made no protest
against the cancellation of his policies, but simply said he would
need no more policies, as he would erect fireproof buildings in which
there would be no "moral risk."
This promise of Edison's, made at the time of his so-called failure
and pondered during the years of his tremendous activities, was
not redeemed until he had retired from the business of invention
as a means of gaining riches. "I am not making these experiments
for money," Edison has said many times. "This model represents the
character of the house which I will construct of concrete. I believe
it can be built by machinery in lots of 100 or more at one location
for a price which will be so low that it can be purchased or rented
by families whose total income is not more than $550 per annum. It is
an attempt to solve the housing question by a practical application
of science, and the latest advancement in cement and mechanical
engineering."
[Illustration: HUGE CONCRETE MOULDS AT PANAMA
These great locks are made as monoliths or in moulds of one
piece, the whole making the greatest masonry work the world has
ever seen.]
[Illustration: CONCRETE LOCKS ON THE PANAMA CANAL
The Gatun middle locks, east chamber, looking south from the east
bank.]
Edison's plan, as we have seen before, was simply to make a set
of moulds in the shape of the house he desired to build, run the
concrete into them, let them stand until the material had settled,
and then take down the retaining surfaces, exposing to view the
finished house.
It was contrary to all the previous ideas in building, and was
ridiculed by many famous architects. Nevertheless, tremendous
obstacles are the stuff upon which Edison's genius feeds, and he only
worked the harder to produce a concrete that would be liquid enough
to fill all the intricate spaces and turns in the moulds and yet
sufficiently thick to prevent the sand or gravel in the concrete from
sinking to the bottom. Thus, it first had to run like thin mush and
then set in walls and floors harder than any brick or stone. Another
of the difficulties to be overcome was to discover a concrete that
would give perfectly smooth walls.
Although this may sound very simple, it has not yet been completely
worked out in this country, owing to the heavy demands on Edison's
time. The perfected process, however, will be made known just as soon
as the inventor can find time to complete certain small details that
he wants to clear up before giving the system to the world. A French
syndicate working along Edison's ideas for a poured house has made
some progress and it is reported they have constructed two attractive
dwellings with considerable success. One of these is at Santpoort,
Holland, and the other near Paris.
Whether the houses are poured completely in one mould, or whether
they are built a story at a time on different days, this newest form
of house building is carried on along about the same lines.
"Let us just suppose," said the scientist, "that we are standing on
a building site in some pretty suburb of a great city. We will also
suppose that an Edison poured house is to be erected there. Plans are
drawn beforehand for a small house of simple arrangement and a set
of steel moulds in convenient sizes are turned out. These moulds all
have connections so they can be set up and joined together in one
piece. First, we see that a solid concrete cellar floor, called the
'footing', has been laid down just the size and shape of the house.
A crowd of skilled workmen quickly set up the moulds on this footing
and lock them together. The moulds make one complete shell of the
house, from cellar to roof, just as it will appear when completed.
Reinforcing rods are placed in the mould so that they will be left in
the concrete walls, floors, etc., of the house after the steel shell
is taken away.
"Nearby we see a few more skilled workmen mixing the concrete in
great vats. When the mould and the material are ready we see the
concrete taken to a tank on the roof and poured into troughs which
carry the stuff to a number of different holes through which it
flows into the mould. We hear it splash, splash, splash as it
gradually fills every space in the shell, and finally after six hours
or so it overflows at the roof. The main part of the work is now done
and we can go away for a few days while the liquid in the shell sets,
or turns to the hardest kind of stone.
"After about six days we return to see the moulds unlocked, taken
down and the complete house standing ready with walls, floors,
stairways, chimneys, bathtubs, stationary tubs in the cellar,
electric-wire conduits, water, gas and heating pipes all complete. In
making the moulds the spaces for bathtubs, wash-tubs, electric wiring
and piping for gas, water, and heat, are just as carefully arranged
as walls and floors. The only work necessary after the concrete has
set is to put in the doors and windows, install the furnace and
necessary fixtures for heating, lighting and plumbing and connect
them up ready for use. No plaster is used in these houses, but the
walls can be tinted or decorated just as the landlord or occupant
desires."
The boy's friend went on to say that one might think that this
was about as far as science could carry the use of concrete, but
Edison said to himself: "If we can make houses, why can't we make
furniture?" and he set about experimenting with poured furniture. He
obtained some wonderful results with this newest use of concrete, and
in his Orange laboratory he has several cabinets, chairs, and other
articles of furniture that are every bit as attractive to look at as
wooden furniture and that are practically indestructible.
"And my concrete furniture will be cheap, as well as strong," says
Edison. "If I couldn't put it out cheaper than the oak that comes
from Grand Rapids, I wouldn't go into the business. If a newlywed
starts out with, say, $450 worth of furniture on the installment
plan, I feel confident that we can give him more artistic and more
durable furniture for $200. I'll also be able to put out a whole
bedroom set for $5 or $6."
At present the weight of this concrete furniture is about one third
greater than wooden furniture, but Edison is confident he can reduce
this excess to one quarter. The concrete surface can, of course,
be stained in imitation of any wood finish. The phonograph cabinet
shown at the left of Edison in the picture opposite page 281 has been
trimmed in white and gold. Its surface resembles enamelled wood. The
cabinet at his right is the old style wooden type.
This concrete cabinet easily withstood the hard usage of shipment by
freight for a long distance.
[Illustration: THE WORLD-WIDE USE OF CONCRETE
Courtesy of the Atlas Portland Cement Co.
An eight-story all-concrete office building under construction in
Portland, Maine.]
[Illustration:
Courtesy of the Atlas Portland Cement Co.
A perfect little model of the great Gatun Locks of the Panama
Canal.]
[Illustration: THE CATSKILL AQUEDUCT, ONE OF THE WORLD'S GREATEST
CONCRETE WORKS
Laying a level section of the great concrete tunnel through which
New York City is to get its drinking water.]
[Illustration: THE AQUEDUCT DEEP UNDER GROUND
A partially completed section showing the concrete work. Note the
size of the tunnel.]
Of course, the poured concrete furniture is made in just the same
way as the houses except that it is a much simpler process. It is a
very easy matter to set up a steel mould for a chair, a cabinet, a
dresser, or a bedstead, whereas a house, with its tubs, conduits,
stairways, hallways, doorways, window frames, plumbing system, etc.,
is a most complex matter, requiring a set of moulds that could be put
together properly by only a man who combined the highest abilities
of an architect, a builder, an engineer, and a mechanic. Although
concrete has been used for many years in making garden furniture,
Edison's plan for making finished indoor pieces with it is entirely
new.
But to return to the houses; Edison says it is just as easy to make
poured dwellings in decorative designs as in plain ones. It is
only necessary to have the moulds cast in the desired shape. It is
his idea to have all the poured houses pretty as well as perfectly
sanitary and substantial. He intends that there shall be many
different kinds of moulds, and also that each set of moulds shall be
so cast that it can be joined in different ways, in order to give the
houses a variety of appearance. Thus, in a small town where a large
number of poured houses were set up, there would be no two exactly
alike if the owners preferred to have them different.
According to the plans Edison now has on foot, the first complete
poured houses will have on the main floor two rooms, the living
room and dining room, while on the second floor there will be four
rooms, a bathroom and hallway. Of course as the main idea is to give
perfectly sanitary and comfortable houses, there will be plenty of
windows, for lots of fresh air and sunlight. Edison figures that
he can build a house of poured concrete for $1,200 that would cost
$30,000 if built of cut stone. Furthermore, he figures that the rent
ought to be about $10 per month, as he will only license reputable
concerns to use his patents, and his licenses will stipulate the
approximate rent that can be charged.
Thus, the high cost of living about which we all hear so much at the
family dinner table as well as everywhere else is being attacked by
science and invention through a new channel, and Edison's latest
invention can be expected soon to give good homes at low rents to
thousands of families now paying exorbitant prices for dark stuffy
city flats.
It was significant that at the celebration of Edison's sixty-fifth
birthday, February 10, 1912, the great American inventor should sit
at the head of the table surrounded by his family and associates
facing a perfect model of one of his poured cement houses. The chair
in which he sat, to all appearances was beautiful mahogany, but in
reality was cast in a mould of Edison concrete at the Edison plant.
At the place of each guest was a bronze paperweight, appropriately
engraved, with Edison's favourite motto:
"All things come to him who hustles while he waits."
HISTORY OF CONCRETE
Although concrete is in truth the newest building material in
our time, it is the oldest known to civilization because it was
the stuff with which the eternal buildings of ancient Rome were
constructed. Even before the Romans used concrete it was used by the
Eygptians, more than 4,000 years ago. Every boy will remember from
his history classes that the Egyptians, so far as we can learn, were
the first people in the history of the world to reach a high state of
civilization. Every boy also will remember that the only way we know
this is through the evidence of ruins of tombs and buildings. Many of
these buildings were made of a material very much like concrete that
must have been made in some such manner as concrete is made nowadays.
About 2,000 years later, long after the Egyptian civilization had
died, the men of Carthage discovered concrete for themselves and
built a marvellous aqueduct 70 miles long, through which water
was brought to their city. It was carried across a great valley
over about 1,000 arches, many of which are still standing in good
condition.
To the Romans, however, we are indebted for some of the best examples
of ancient concrete work. They used this material in their wonderful
city for buildings, bridges, sewers, aqueducts, water mains, and in
fact in a great many of the ways that we have seen it is used to-day.
The great Coliseum and the Pantheon at Rome are relics of the skill
of the ancient architects in the use of concrete.
Although many historians think that the secret of making cementious
building material was lost from the fall of Rome until the middle
of the eighteenth century, there are ruins of ancient castles which
stood in mediæval times in Europe which indicate at least some use of
concrete.
The real discoverer of natural cement in our modern times though,
was John Smeaton, who will be remembered by the readers of "The
Boy's Second Book of Inventions" as the man who built the first
rock lighthouse at Eddystone, England, in 1756. In his great work
he discovered a kind of limestone with which he could make a cement
that would set, or harden, under water. His discovery was hailed as
the recovery of the secret of the ancient Romans of making hydraulic
cement. It was so called because it would harden under water.
In 1796, Joseph Parker, another Englishman, made what he called Roman
cement. Several others followed, and in 1818 natural cement was
first made in the United States by Canvass White near Fayetteville,
N. Y. The material was made from natural rock and was used in the
construction of the Erie Canal.
All of these early cements are called natural cements by engineers
nowadays, because they were made from natural rock. It was only
necessary to find a clayey limestone which contained a certain
percentage of iron oxide and two other minerals known as silica and
alumina. The limestone was crushed to a convenient size and was
burned in a kiln. The heat turned the stuff into cinders which, when
ground to a fine powder and mixed with water, would make a cement
that would harden under either air or water very quickly, and last
for practically all time. Just for the sake of those who have studied
chemistry we will say that in this process the heat drives off the
carbon dioxide in the limestone, and the lime, combining with the
silica alumina and iron oxide, forms a mass containing mineral
properties called silicates, aluminates, and ferrites of lime. These
properties mixed with the water make natural cement. In the United
States, natural cement was called Rosendale cement, because it was
first made commercially in a town of New York State by that name.
The supply of natural cement, however, is limited, because the proper
kind of limestone is only found in a few places. Consequently, when
an artificial mortar called Portland cement was invented in 1824, the
world took a step forward that could not be measured in those days.
Most authorities give the credit for the invention to Joseph Aspdin,
a bricklayer of Leeds, England. He took out a patent on the material
and in 1825 set up a large factory. In 1828 Portland cement was used
in the Thames tunnel, making the first time that the material figured
in any big engineering work. In those days even the most enthusiastic
supporters of cement little dreamed that in this modern age it would
be the material that would make possible such tremendous victories
over the obstacles of nature as the Panama Canal, the tunnels under
the rivers that surround New York and the great dams that hold back
the waters all over the country.
Aspdin, however, is not given the credit for the invention of
Portland cement by all authorities, as some claim that Isaac Johnson,
also an Englishman, who early in 1912 died at the age of 104, was
really the first man to invent a practical, commercial, artificial
cement.
The advantage in Portland cement is that it can be made of a number
of different kinds of earth, to be found in many different parts
of the world, and makes a far stronger rock. It sets more slowly
than natural or hydraulic cement, but is more satisfactory for use
in reinforced concrete work. In the Lehigh Valley, where about two
thirds of the Portland cement used in the United States is made,
the raw material is a rock, called cement rock, and limestone. In
New York State they make Portland cement of limestone and clay;
in the Middle West they make it of marl and clay, while in other
Western States they make it of chalk and clay. In Europe slag is
sometimes used. The artificial product contains lime oxide, silica,
alumina, iron oxide, and other minerals in varying quantities, but
the necessary ones are silica, alumina, and lime. In making Portland
cement the raw material is ground into a fine powder and poured into
one end of a long cylindrical kiln which looks like a smokestack
lying on its side. Powdered coal is shot into the kiln, where it is
kept burning, at a heat of about 2,500 to 3,000 degrees Fahrenheit.
After the raw material has been burned thoroughly and is taken from
the kiln it looks like little cinders or clinkers about the size of
marbles. The cement clinker is then cooled and ground to a powder,
after which it is stored away for a little while to season.
The first Portland cement ever made in the United States was turned
out by David O. Saylor, of Coplay, Pa., in 1875, but the development
of the new industry was very slow, as builders and engineers seemed
to be blind to the great possibilities of the material that built
Imperial Rome. In 1890, nearly twenty years after the process was
introduced in America, only 335,500 barrels of Portland cement were
manufactured in this country. The country woke up to the situation a
few years later, and in 1905 there were manufactured in the United
States 35,246,812 barrels of Portland cement. In 1911 the industry
turned out the stupendous total of 77,877,236 barrels.
This was because the age of concrete had dawned on the world and man
had learned in those years that by mixing gravel and sand with cement
he could make a material cheaper, more easily handled, and far more
lasting than wood, brick or some stone.
As Edison once said to some of his associates:
"I think the age of concrete has started, and I believe I can prove
that the most beautiful houses that our architects can conceive
can be cast in one operation in iron forms at a cost, which, by
comparison with present methods, will be surprising. Then even the
poorest man among us will be enabled to own a home of his own--a home
that will last for centuries with no cost for insurance or repairs,
and be as exchangeable for other property as a United States bond."
The technical definition of concrete is as follows: "Concrete is
a species of artificial stone formed by mixing cement mortar with
broken stone or gravel. Cement is the active element called the
_matrix_ and the sand and stone forms the body of the mixture called
the _aggregate_."
The ingredients are mixed in different proportions for different
work. A common proportion is 1 part cement, 2 parts sand, and 5
parts broken stone or gravel. Cement users speak of this as a "1:
2: 5 mixture." Sometimes the gravel is left out and a mixture of 1
part cement to 3 or 4 parts sand is made. The cement binds the mass
together and sand fills up any little vacant spaces about the gravel,
making what is called a dense mixture.
[Illustration: THE SILENT KNIGHT MOTOR
Two views of the latest automobile engine. At the top can be seen
the sliding sleeves, the inlets and outlets which do away with
valves]
[Illustration: A PORTABLE ARMY WIRELESS OUTFIT
The Signal Service is rapidly increasing its wireless equipment
for use on land.]
[Illustration: THE WIRELESS IN THE NAVY
Practically all of Uncle Sam's warships and Navy Yards now are
equipped with wireless, and a regular navy wireless operators'
school is maintained at the Brooklyn Navy Yard.]
From the use of concrete it was only a short step to reinforced
concrete, or, concrete braced on the inside with iron or steel rods.
It is sometimes called concrete steel, ferro-concrete, and armoured
concrete. If we asked an engineer the idea in using reinforced
concrete he might say to us that the steel when imbedded, united so
closely with the concrete as to form one single mass of very great
strength. Steel rods add to the _tensile_ strength of concrete which
alone has a tremendous strength under _compression_. In other words,
steel does not break nor stretch easily; that is, it has great
tensile strength. Concrete has great strength under compression;
that is, it will hold up an enormous weight without crushing. Thus,
a concrete beam alone might crack on the bottom, because it has not
as great tensile strength as steel. But, if we put steel rods into a
concrete mould, an inch or so from the bottom, turn out a reinforced
concrete beam, for instance, and place it in the building, with the
reinforcement at the bottom, we use a beam in which the strength
of the concrete and iron is combined. Thus, when a great weight is
placed on the top of the beam the concrete resists the compression
of the weight, and the reinforcement at the bottom, by its tensile
strength, prevents the beam from cracking where the strain of the
weight is greatest.
That is what the engineer might tell us is the theory of reinforced
concrete, and the practice requires the highest engineering skill
and technical knowledge, but in the simplest terms, it is concrete,
braced by an imbedded skeleton of steel. In actual practice the
reinforcing rods run both ways, or diagonally, just as the engineers
decide it is necessary to resist the particular kind of stress that
the wall or beam must withstand.
Reinforced concrete was first used, so far as known, by M. Lambot,
who exhibited a small rowboat made of that material at the World's
Fair in Paris, in 1855. The sides and bottom of the boat were 1-1/2
inches thick, with reinforcement of steel wires. The boat is still
in use at Merval, France. F. Joseph Monier, however, is called the
"father of reinforced concrete," as he took out the first patent on
it in France in 1865. Monier was a gardener and had experimented with
large urns for flowers and shrubs. He wanted to make his pots lighter
but just as strong, so he tried making some of concrete with a wire
netting imbedded in the material. But even then the world did not
realize that his accomplishment was more important to mankind than a
great many of the wars that had been fought, and little was done with
concrete as a building material until the Germans developed it.
Reinforced concrete was not used in the United States, according to
the best records, until 1875, when W. E. Ward, without having studied
the subject very carefully, built himself a house of it, in Port
Chester, N. Y. He made the whole thing, including foundation, outside
walls, cornices, towers, and roof of reinforced concrete, placing
the steel rods where his own good judgment told him they would do
the most good. About this time the Ransome Cement Company began to
use the material for building, and put up a great many strong and
beautiful structures, still to be seen in California and elsewhere.
Finally, bit by bit, in the face of opposition of all kinds,
reinforced concrete came to be recognized by architects, engineers,
and builders as one of the best materials for certain kinds of work.
To-day we find that most of the predictions of the early enthusiasts
have been fulfilled and that the age of concrete has dawned. That it
will be used even more extensively in the future, as men learn more
and more about this wonderful artificial stone, is certain.