EDISON PORTLAND CEMENT
NEW developments in recent years have been more striking than the
general adoption of cement for structural purposes of all kinds in
the United States; or than the increase in its manufacture here. As
a material for the construction of office buildings, factories, and
dwellings, it has lately enjoyed an extraordinary vogue; yet every
indication is confirmatory of the belief that such use has barely begun.
Various reasons may be cited, such as the growing scarcity of wood, once
the favorite building material in many parts of the country, and the
increasing dearness of brick and stone. The fact remains, indisputable,
and demonstrated flatly by the statistics of production. In 1902 the
American output of cement was placed at about 21,000,000 barrels,
valued at over $17,000,000. In 1907 the production is given as nearly
49,000,000 barrels. Here then is an industry that doubled in five years.
The average rate of industrial growth in the United States is 10 per
cent. a year, or doubling every ten years. It is a singular fact that
electricity also so far exceeds the normal rate as to double in value
and quantity of output and investment every five years. There is perhaps
more than ordinary coincidence in the association of Edison with two
such active departments of progress.
As a purely manufacturing business the general cement industry is one
of even remote antiquity, and if Edison had entered into it merely as
a commercial enterprise by following paths already so well trodden, the
fact would hardly have been worthy of even passing notice. It is not in
his nature, however, to follow a beaten track except in regard to the
recognition of basic principles; so that while the manufacture of Edison
Portland cement embraces the main essentials and familiar processes of
cement-making, such as crushing, drying, mixing, roasting, and grinding,
his versatility and originality, as exemplified in the conception and
introduction of some bold and revolutionary methods and devices, have
resulted in raising his plant from the position of an outsider to the
rank of the fifth largest producer in the United States, in the short
space of five years after starting to manufacture.
Long before his advent in cement production, Edison had held very
pronounced views on the value of that material as the one which would
obtain largely for future building purposes on account of its stability.
More than twenty-five years ago one of the writers of this narrative
heard him remark during a discussion on ancient buildings: "Wood will
rot, stone will chip and crumble, bricks disintegrate, but a cement and
iron structure is apparently indestructible. Look at some of the old
Roman baths. They are as solid as when they were built." With such
convictions, and the vast fund of practical knowledge and experience he
had gained at Edison in the crushing and manipulation of large masses of
magnetic iron ore during the preceding nine years, it is not surprising
that on that homeward railway journey, mentioned at the close of the
preceding chapter, he should have decided to go into the manufacture
of cement, especially in view of the enormous growth of its use for
structural purposes during recent times.
The field being a new one to him, Edison followed his usual course of
reading up every page of authoritative literature on the subject, and
seeking information from all quarters. In the mean time, while he was
busy also with his new storage battery, Mr. Mallory, who had been hard
at work on the cement plan, announced that he had completed arrangements
for organizing a company with sufficient financial backing to carry on
the business; concluding with the remark that it was now time to engage
engineers to lay out the plant. Edison replied that he intended to
do that himself, and invited Mr. Mallory to go with him to one of the
draughting-rooms on an upper floor of the laboratory.
Here he placed a large sheet of paper on a draughting-table, and
immediately began to draw out a plan of the proposed works, continuing
all day and away into the evening, when he finished; thus completing
within the twenty-four hours the full lay-out of the entire plant as
it was subsequently installed, and as it has substantially remained
in practical use to this time. It will be granted that this was a
remarkable engineering feat, especially in view of the fact that Edison
was then a new-comer in the cement business, and also that if the
plant were to be rebuilt to-day, no vital change would be desirable
or necessary. In that one day's planning every part was considered and
provided for, from the crusher to the packing-house. From one end to the
other, the distance over which the plant stretches in length is about
half a mile, and through the various buildings spread over this space
there passes, automatically, in course of treatment, a vast quantity
of material resulting in the production of upward of two and a quarter
million pounds of finished cement every twenty-four hours, seven days in
the week.
In that one day's designing provision was made not only for all
important parts, but minor details, such, for instance, as the carrying
of all steam, water, and air pipes, and electrical conductors in a large
subway running from one end of the plant to the other; and, an oiling
system for the entire works. This latter deserves special mention, not
only because of its arrangement for thorough lubrication, but also on
account of the resultant economy affecting the cost of manufacture.
Edison has strong convictions on the liberal use of lubricants, but
argued that in the ordinary oiling of machinery there is great waste,
while much dirt is conveyed into the bearings. He therefore planned
a system by which the ten thousand bearings in the plant are oiled
automatically; requiring the services of only two men for the entire
work. This is accomplished by a central pumping and filtering plant
and the return of the oil from all parts of the works by gravity. Every
bearing is made dust-proof, and is provided with two interior pipes. One
is above and the other below the bearing. The oil flows in through the
upper pipe, and, after lubricating the shaft, flows out through the
lower pipe back to the pumping station, where any dirt is filtered out
and the oil returned to circulation. While this system of oiling is
not unique, it was the first instance of its adaptation on so large and
complete a scale, and illustrates the far-sightedness of his plans.
In connection with the adoption of this lubricating system there
occurred another instance of his knowledge of materials and intuitive
insight into the nature of things. He thought that too frequent
circulation of a comparatively small quantity of oil would, to some
extent, impair its lubricating qualities, and requested his assistants
to verify this opinion by consultation with competent authorities. On
making inquiry of the engineers of the Standard Oil Company, his theory
was fully sustained. Hence, provision was made for carrying a large
stock of oil, and for giving a certain period of rest to that already
used.
A keen appreciation of ultimate success in the production of a fine
quality of cement led Edison to provide very carefully in his original
scheme for those details that he foresaw would become requisite--such,
for instance, as ample stock capacity for raw materials and their
automatic delivery in the various stages of manufacture, as well
as mixing, weighing, and frequent sampling and analyzing during the
progress through the mills. This provision even included the details of
the packing-house, and his perspicacity in this case is well sustained
from the fact that nine years afterward, in anticipation of building an
additional packing-house, the company sent a representative to different
parts of the country to examine the systems used by manufacturers in
the packing of large quantities of various staple commodities involving
somewhat similar problems, and found that there was none better than
that devised before the cement plant was started. Hence, the order was
given to build the new packing-house on lines similar to those of the
old one.
Among the many innovations appearing in this plant are two that stand
out in bold relief as indicating the large scale by which Edison
measures his ideas. One of these consists of the crushing and grinding
machinery, and the other of the long kilns. In the preceding chapter
there has been given a description of the giant rolls, by means of which
great masses of rock, of which individual pieces may weigh eight or more
tons, are broken and reduced to about a fourteen-inch size. The economy
of this is apparent when it is considered that in other cement plants
the limit of crushing ability is "one-man size"--that is, pieces not too
large for one man to lift.
The story of the kiln, as told by Mr. Mallory, is illustrative of
Edison's tendency to upset tradition and make a radical departure from
generally accepted ideas. "When Mr. Edison first decided to go into
the cement business, it was on the basis of his crushing-rolls and air
separation, and he had every expectation of installing duplicates of the
kilns which were then in common use for burning cement. These kilns were
usually made of boiler iron, riveted, and were about sixty feet long and
six feet in diameter, and had a capacity of about two hundred barrels of
cement clinker in twenty-four hours.
"When the detail plans for our plant were being drawn, Mr. Edison and I
figured over the coal capacity and coal economy of the sixty-foot kiln,
and each time thought that both could he materially bettered. After
having gone over this matter several times, he said: 'I believe I
can make a kiln which will give an output of one thousand barrels in
twenty-four hours.' Although I had then been closely associated with him
for ten years and was accustomed to see him accomplish great things, I
could not help feeling the improbability of his being able to jump into
an old-established industry--as a novice--and start by improving the
'heart' of the production so as to increase its capacity 400 per
cent. When I pressed him for an explanation, he was unable to give any
definite reasons, except that he felt positive it could be done. In this
connection let me say that very many times I have heard Mr. Edison make
predictions as to what a certain mechanical device ought to do in the
way of output and costs, when his statements did not seem to be even
among the possibilities. Subsequently, after more or less experience,
these predictions have been verified, and I cannot help coming to the
conclusion that he has a faculty, not possessed by the average mortal,
of intuitively and correctly sizing up mechanical and commercial
possibilities.
"But, returning to the kiln, Mr. Edison went to work immediately and
very soon completed the design of a new type which was to be one hundred
and fifty feet long and nine feet in diameter, made up in ten-foot
sections of cast iron bolted together and arranged to be revolved
on fifteen bearings. He had a wooden model made and studied it
very carefully, through a series of experiments. These resulted so
satisfactorily that this form was finally decided upon, and ultimately
installed as part of the plant.
"Well, for a year or so the kiln problem was a nightmare to me. When we
started up the plant experimentally, and the long kiln was first put in
operation, an output of about four hundred barrels in twenty-four hours
was obtained. Mr. Edison was more than disappointed at this result. His
terse comment on my report was: 'Rotten. Try it again.' When we became a
little more familiar with the operation of the kiln we were able to
get the output up to about five hundred and fifty barrels, and a little
later to six hundred and fifty barrels per day. I would go down to
Orange and report with a great deal of satisfaction the increase in
output, but Mr. Edison would apparently be very much disappointed, and
often said to me that the trouble was not with the kiln, but with our
method of operating it; and he would reiterate his first statement that
it would make one thousand barrels in twenty-four hours.
"Each time I would return to the plant with the determination to
increase the output if possible, and we did increase it to seven
hundred and fifty, then to eight hundred and fifty barrels. Every time I
reported these increases Mr. Edison would still be disappointed. I said
to him several times that if he was so sure the kiln could turn out one
thousand barrels in twenty-four hours we would be very glad to have him
tell us how to do it, and that we would run it in any way he directed.
He replied that he did not know what it was that kept the output down,
but he was just as confident as ever that the kiln would make one
thousand barrels per day, and that if he had time to work with and watch
the kiln it would not take him long to find out the reasons why. He had
made a number of suggestions throughout these various trials, however,
and, as we continued to operate, we learned additional points in
handling, and were able to get the output up to nine hundred barrels,
then one thousand, and finally to over eleven hundred barrels per day,
thus more than realizing the prediction made by Mr. Edison before even
the plans were drawn. It is only fair to say, however, that prolonged
experience has led us to the conclusion that the maximum economy in
continuous operation of these kilns is obtained by working them at a
little less than their maximum capacity.
"It is interesting to note, in connection with the Edison type of kiln,
that when the older cement manufacturers first learned of it, they
ridiculed the idea universally, and were not slow to predict our early
'finish' as cement manufacturers. The ultimate success of the kiln,
however, proved their criticisms to be unwarranted. Once aware of
its possibility, some of the cement manufacturers proceeded to avail
themselves of the innovation (at first without Mr. Edison's consent),
and to-day more than one-half of the Portland cement produced in this
country is made in kilns of the Edison type. Old plants are lengthening
their kilns wherever practicable, and no wide-awake manufacturer
building a modern plant could afford to install other than these long
kilns. This invention of Mr. Edison has been recognized by the larger
cement manufacturers, and there is every prospect now that the entire
trade will take licenses under his kiln patents."
When he decided to go into the cement business, Edison was
thoroughly awake to the fact that he was proposing to "butt into" an
old-established industry, in which the principal manufacturers
were concerns of long standing. He appreciated fully its inherent
difficulties, not only in manufacture, but also in the marketing of the
product. These considerations, together with his long-settled principle
of striving always to make the best, induced him at the outset to study
methods of producing the highest quality of product. Thus he was led to
originate innovations in processes, some of which have been preserved
as trade secrets; but of the others there are two deserving special
notice--namely, the accuracy of mixing and the fineness of grinding.
In cement-making, generally speaking, cement rock and limestone in
the rough are mixed together in such relative quantities as may be
determined upon in advance by chemical analysis. In many plants this
mixture is made by barrow or load units, and may be more or less
accurate. Rule-of-thumb methods are never acceptable to Edison, and he
devised therefore a system of weighing each part of the mixture, so
that it would be correct to a pound, and, even at that, made the device
"fool-proof," for as he observed to one of his associates: "The man at
the scales might get to thinking of the other fellow's best girl, so
fifty or a hundred pounds of rock, more or less, wouldn't make much
difference to him." The Edison checking plan embraces two hoppers
suspended above two platform scales whose beams are electrically
connected with a hopper-closing device by means of needles dipping into
mercury cups. The scales are set according to the chemist's weighing
orders, and the material is fed into the scales from the hoppers. The
instant the beam tips, the connection is broken and the feed stops
instantly, thus rendering it impossible to introduce any more material
until the charge has been unloaded.
The fine grinding of cement clinker is distinctively Edisonian in
both origin and application. As has been already intimated, its author
followed a thorough course of reading on the subject long before
reaching the actual projection or installation of a plant, and he had
found all authorities to agree on one important point--namely, that the
value of cement depends upon the fineness to which it is ground. [16] He
also ascertained that in the trade the standard of fineness was that 75
per cent. of the whole mass would pass through a 200-mesh screen. Having
made some improvements in his grinding and screening apparatus, and
believing that in the future engineers, builders, and contractors
would eventually require a higher degree of fineness, he determined, in
advance of manufacturing, to raise the standard ten points, so that at
least 85 per cent. of his product should pass through a 200-mesh screen.
This was a bold step to be taken by a new-comer, but his judgment,
backed by a full confidence in ability to live up to this standard, has
been fully justified in its continued maintenance, despite the early
incredulity of older manufacturers as to the possibility of attaining
such a high degree of fineness.
[Footnote 16: For a proper understanding and full
appreciation of the importance of fine grinding, it may be
explained that Portland cement (as manufactured in the
Lehigh Valley) is made from what is commonly spoken of as
"cement rock," with the addition of sufficient limestone to
give the necessary amount of lime. The rock is broken down
and then ground to a fineness of 80 to 90 per cent. through
a 200-mesh screen. This ground material passes through kilns
and comes out in "clinker." This is ground and that part of
this finely ground clinker that will pass a 200-mesh screen
is cement; the residue is still clinker. These coarse
particles, or clinkers, absorb water very slowly, are
practically inert, and have very feeble cementing
properties. The residue on a 200-mesh screen is useless.]
If Edison measured his happiness, as men often do, by merely commercial
or pecuniary rewards of success, it would seem almost redundant to state
that he has continued to manifest an intense interest in the cement
plant. Ordinarily, his interest as an inventor wanes in proportion to
the approach to mere commercialism--in other words, the keenness of his
pleasure is in overcoming difficulties rather than the mere piling up of
a bank account. He is entirely sensible of the advantages arising from
a good balance at the banker's, but that has not been the goal of his
ambition. Hence, although his cement enterprise reached the commercial
stage a long time ago, he has been firmly convinced of his own ability
to devise still further improvements and economical processes of greater
or less fundamental importance, and has, therefore, made a constant
study of the problem as a whole and in all its parts. By means of
frequent reports, aided by his remarkable memory, he keeps in as close
touch with the plant as if he were there in person every day, and
is thus enabled to suggest improvement in any particular detail. The
engineering force has a great respect for the accuracy of his knowledge
of every part of the plant, for he remembers the dimensions and details
of each item of machinery, sometimes to the discomfiture of those who
are around it every day.
A noteworthy instance of Edison's memory occurred in connection with
this cement plant. Some years ago, as its installation was nearing
completion, he went up to look it over and satisfy himself as to what
needed to be done. On the arrival of the train at 10.40 in the morning,
he went to the mill, and, with Mr. Mason, the general superintendent,
started at the crusher at one end, and examined every detail all the way
through to the packing-house at the other end. He made neither notes nor
memoranda, but the examination required all the day, which happened to
be a Saturday. He took a train for home at 5.30 in the afternoon, and on
arriving at his residence at Orange, got out some note-books and began
to write entirely from memory each item consecutively. He continued
at this task all through Saturday night, and worked steadily on until
Sunday afternoon, when he completed a list of nearly six hundred items.
The nature of this feat is more appreciable from the fact that a large
number of changes included all the figures of new dimensions he had
decided upon for some of the machinery throughout the plant.
As the reader may have a natural curiosity to learn whether or not the
list so made was practical, it may be stated that it was copied and
sent up to the general superintendent with instructions to make the
modifications suggested, and report by numbers as they were attended to.
This was faithfully done, all the changes being made before the plant
was put into operation. Subsequent experience has amply proven the value
of Edison's prescience at this time.
Although Edison's achievements in the way of improved processes and
machinery have already made a deep impression in the cement industry,
it is probable that this impression will become still more profoundly
stamped upon it in the near future with the exploitation of his "Poured
Cement House." The broad problem which he set himself was to provide
handsome and practically indestructible detached houses, which could be
taken by wage-earners at very moderate monthly rentals. He turned
this question over in his mind for several years, and arrived at the
conclusion that a house cast in one piece would be the answer. To
produce such a house involved the overcoming of many engineering and
other technical difficulties. These he attacked vigorously and disposed
of patiently one by one.
In this connection a short anecdote may be quoted from Edison as
indicative of one of the influences turning his thoughts in this
direction. In the story of the ore-milling work, it has been noted that
the plant was shut down owing to the competition of the cheap ore
from the Mesaba Range. Edison says: "When I shut down, the insurance
companies cancelled my insurance. I asked the reason why. 'Oh,' they
said, 'this thing is a failure. The moral risk is too great.' 'All
right; I am glad to hear it. I will now construct buildings that won't
have any moral risk.' I determined to go into the Portland cement
business. I organized a company and started cement-works which have
now been running successfully for several years. I had so perfected the
machinery in trying to get my ore costs down that the making of cheap
cement was an easy matter to me. I built these works entirely of
concrete and steel, so that there is not a wagon-load of lumber in them;
and so that the insurance companies would not have any possibility of
having any 'moral risk.' Since that time I have put up numerous factory
buildings all of steel and concrete, without any combustible whatever
about them--to avoid this 'moral risk.' I am carrying further the
application of this idea in building private houses for poor people, in
which there will be no 'moral risk' at all--nothing whatever to burn,
not even by lightning."
As a casting necessitates a mold, together with a mixture sufficiently
fluid in its nature to fill all the interstices completely, Edison
devoted much attention to an extensive series of experiments for
producing a free-flowing combination of necessary materials. His
proposition was against all precedent. All expert testimony pointed to
the fact that a mixture of concrete (cement, sand, crushed stone, and
water) could not be made to flow freely to the smallest parts of an
intricate set of molds; that the heavy parts of the mixture could not
be held in suspension, but would separate out by gravity and make
an unevenly balanced structure; that the surface would be full of
imperfections, etc.
Undeterred by the unanimity of adverse opinions, however, he pursued his
investigations with the thorough minuteness that characterizes all his
laboratory work, and in due time produced a mixture which on elaborate
test overcame all objections and answered the complex requirements
perfectly, including the making of a surface smooth, even, and entirely
waterproof. All the other engineering problems have received study in
like manner, and have been overcome, until at the present writing the
whole question is practically solved and has been reduced to actual
practice. The Edison poured or cast cement house may be reckoned as a
reality.
The general scheme, briefly outlined, is to prepare a model and plans of
the house to be cast, and then to design a set of molds in sections of
convenient size. When all is ready, these molds, which are of cast iron
with smooth interior surfaces, are taken to the place where the house
is to be erected. Here there has been provided a solid concrete cellar
floor, technically called "footing." The molds are then locked together
so that they rest on this footing. Hundreds of pieces are necessary for
the complete set. When they have been completely assembled, there will
be a hollow space in the interior, representing the shape of the house.
Reinforcing rods are also placed in the molds, to be left behind in the
finished house.
Next comes the pouring of the concrete mixture into this form. Large
mechanical mixers are used, and, as it is made, the mixture is dumped
into tanks, from which it is conveyed to a distributing tank on the top,
or roof, of the form. From this tank a large number of open troughs or
pipes lead the mixture to various openings in the roof, whence it flows
down and fills all parts of the mold from the footing in the basement
until it overflows at the tip of the roof.
The pouring of the entire house is accomplished in about six hours,
and then the molds are left undisturbed for six days, in order that the
concrete may set and harden. After that time the work of taking away
the molds is begun. This requires three or four days. When the molds are
taken away an entire house is disclosed, cast in one piece, from cellar
to tip of roof, complete with floors, interior walls, stairways, bath
and laundry tubs, electric-wire conduits, gas, water, and heating pipes.
No plaster is used anywhere; but the exterior and interior walls
are smooth and may be painted or tinted, if desired. All that is
now necessary is to put in the windows, doors, heater, and lighting
fixtures, and to connect up the plumbing and heating arrangements, thus
making the house ready for occupancy.
As these iron molds are not ephemeral like the wooden framing now used
in cement construction, but of practically illimitable life, it is
obvious that they can be used a great number of times. A complete set
of molds will cost approximately $25,000, while the necessary plant
will cost about $15,000 more. It is proposed to work as a unit plant for
successful operation at least six sets of molds, to keep the men busy
and the machinery going. Any one, with a sheet of paper, can ascertain
the yearly interest on the investment as a fixed charge to be assessed
against each house, on the basis that one hundred and forty-four houses
can be built in a year with the battery of six sets of molds. Putting
the sum at $175,000, and the interest at 6 per cent. on the cost of the
molds and 4 per cent. for breakage, together with 6 per cent. interest
and 15 per cent. depreciation on machinery, the plant charge is
approximately $140 per house. It does not require a particularly acute
prophetic vision to see "Flower Towns" of "Poured Houses" going up in
whole suburbs outside all our chief centres of population.
Edison's conception of the workingman's ideal house has been a broad
one from the very start. He was not content merely to provide a roomy,
moderately priced house that should be fireproof, waterproof, and
vermin-proof, and practically indestructible, but has been solicitous
to get away from the idea of a plain "packing-box" type. He has also
provided for ornamentation of a high class in designing the details of
the structure. As he expressed it: "We will give the workingman and his
family ornamentation in their house. They deserve it, and besides, it
costs no more after the pattern is made to give decorative effects than
it would to make everything plain." The plans have provided for a type
of house that would cost not far from $30,000 if built of cut stone. He
gave to Messrs. Mann & McNaillie, architects, New York, his idea of
the type of house he wanted. On receiving these plans he changed them
considerably, and built a model. After making many more changes in this
while in the pattern shop, he produced a house satisfactory to himself.
This one-family house has a floor plan twenty-five by thirty feet, and
is three stories high. The first floor is divided off into two large
rooms--parlor and living-room--and the upper floors contain four large
bedrooms, a roomy bath-room, and wide halls. The front porch extends
eight feet, and the back porch three feet. A cellar seven and a half
feet high extends under the whole house, and will contain the boiler,
wash-tubs, and coal-bunker. It is intended that the house shall be built
on lots forty by sixty feet, giving a lawn and a small garden.
It is contemplated that these houses shall be built in industrial
communities, where they can be put up in groups of several hundred. If
erected in this manner, and by an operator buying his materials in large
quantities, Edison believes that these houses can be erected complete,
including heating apparatus and plumbing, for $1200 each. This figure
would also rest on the basis of using in the mixture the gravel
excavated on the site. Comment has been made by persons of artistic
taste on the monotony of a cluster of houses exactly alike in
appearance, but this criticism has been anticipated, and the molds are
so made as to be capable of permutations of arrangement. Thus it will
be possible to introduce almost endless changes in the style of house by
variation of the same set of molds.
For more than forty years Edison was avowedly an inventor for purely
commercial purposes; but within the last two years he decided to retire
from that field so far as new inventions were concerned, and to devote
himself to scientific research and experiment in the leisure hours
that might remain after continuing to improve his existing devices.
But although the poured cement house was planned during the commercial
period, the spirit in which it was conceived arose out of an earnest
desire to place within the reach of the wage-earner an opportunity to
better his physical, pecuniary, and mental conditions in so far as that
could be done through the medium of hygienic and beautiful homes at
moderate rentals. From the first Edison has declared that it was not
his intention to benefit pecuniarily through the exploitation of this
project. Having actually demonstrated the practicability and feasibility
of his plans, he will allow responsible concerns to carry them into
practice under such limitations as may be necessary to sustain the basic
object, but without any payment to him except for the actual expense
incurred. The hypercritical may cavil and say that, as a manufacturer of
cement, Edison will be benefited. True, but as ANY good Portland cement
can be used, and no restrictions as to source of supply are enforced,
he, or rather his company, will be merely one of many possible
purveyors.
This invention is practically a gift to the workingmen of the world
and their families. The net result will be that those who care to avail
themselves of the privilege may, sooner or later, forsake the
crowded apartment or tenement and be comfortably housed in sanitary,
substantial, and roomy homes fitted with modern conveniences, and
beautified by artistic decorations, with no outlay for insurance or
repairs; no dread of fire, and all at a rental which Edison believes
will be not more, but probably less than, $10 per month in any city
of the United States. While his achievement in its present status will
bring about substantial and immediate benefits to wage-earners, his
thoughts have already travelled some years ahead in the formulation of a
still further beneficial project looking toward the individual ownership
of these houses on a basis startling in its practical possibilities.