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As We May Think
by Vannevar Bush
This has not been a scientist's war; it has been a war in which all have had a part. The scientists, burying their old professional competition in the demand of a common cause, have shared greatly and learned much. It has been exhilarating to work in effective partnership. Now, for many, this appears to be approaching an end. What are the scientists to do next?
For the biologists, and particularly for the medical scientists, there can be
little indecision, for their war has hardly required them to leave the old
paths. Many indeed have been able to carry on their war research in their
familiar peacetime laboratories. Their objectives remain much the same.
It is the physicists who have been thrown most violently off stride, who have
left academic pursuits for the making of strange destructive gadgets, who have
had to devise new methods for their unanticipated assignments. They have done
their part on the devices that made it possible to turn back the enemy, have
worked in combined effort with the physicists of our allies. They have felt
within themselves the stir of achievement. They have been part of a great team.
Now, as peace approaches, one asks where they will find objectives worthy of
Of what lasting benefit has been man's use of science and of the new
instruments which his research brought into existence? First, they have
increased his control of his material environment. They have improved his food,
his clothing, his shelter; they have increased his security and released him
partly from the bondage of bare existence. They have given him increased
knowledge of his own biological processes so that he has had a progressive
freedom from disease and an increased span of life. They are illuminating the
interactions of his physiological and psychological functions, giving the
promise of an improved mental health.
Science has provided the swiftest communication between individuals; it has
provided a record of ideas and has enabled man to manipulate and to make
extracts from that record so that knowledge evolves and endures throughout the
life of a race rather than that of an individual.
There is a growing mountain of research. But there is increased evidence that
we are being bogged down today as specialization extends. The investigator is
staggered by the findings and conclusions of thousands of other
workers—conclusions which he cannot find time to grasp, much less to remember, as they appear. Yet specialization becomes increasingly necessary for progress, and the effort to bridge between disciplines is correspondingly superficial.
Professionally our methods of transmitting and reviewing the results of
research are generations old and by now are totally inadequate for their
purpose. If the aggregate time spent in writing scholarly works and in reading
them could be evaluated, the ratio between these amounts of time might well be
startling. Those who conscientiously attempt to keep abreast of current
thought, even in restricted fields, by close and continuous reading might well
shy away from an examination calculated to show how much of the previous
month's efforts could be produced on call. Mendel's concept of the laws of
genetics was lost to the world for a generation because his publication did not
reach the few who were capable of grasping and extending it; and this sort of
catastrophe is undoubtedly being repeated all about us, as truly significant
attainments become lost in the mass of the inconsequential.
The difficulty seems to be, not so much that we publish unduly in view of the
extent and variety of present day interests, but rather that publication has
been extended far beyond our present ability to make real use of the record.
The summation of human experience is being expanded at a prodigious rate, and
the means we use for threading through the consequent maze to the momentarily
important item is the same as was used in the days of square-rigged ships.
But there are signs of a change as new and powerful instrumentalities come into
use. Photocells capable of seeing things in a physical sense, advanced
photography which can record what is seen or even what is not, thermionic tubes
capable of controlling potent forces under the guidance of less power than a
mosquito uses to vibrate his wings, cathode ray tubes rendering visible an
occurrence so brief that by comparison a microsecond is a long time, relay
combinations which will carry out involved sequences of movements more reliably
than any human operator and thousands of times as fast—there are plenty of
mechanical aids with which to effect a transformation in scientific records.
Two centuries ago Leibnitz invented a calculating machine which embodied most
of the essential features of recent keyboard devices, but it could not then
come into use. The economics of the situation were against it: the labor
involved in constructing it, before the days of mass production, exceeded the
labor to be saved by its use, since all it could accomplish could be duplicated
by sufficient use of pencil and paper. Moreover, it would have been subject to
frequent breakdown, so that it could not have been depended upon; for at that
time and long after, complexity and unreliability were synonymous.
Babbage, even with remarkably generous support for his time, could not produce
his great arithmetical machine. His idea was sound enough, but construction and
maintenance costs were then too heavy. Had a Pharaoh been given detailed and
explicit designs of an automobile, and had he understood them completely, it
would have taxed the resources of his kingdom to have fashioned the thousands
of parts for a single car, and that car would have broken down on the first
trip to Giza.
Machines with interchangeable parts can now be constructed with great economy
of effort. In spite of much complexity, they perform reliably. Witness the
humble typewriter, or the movie camera, or the automobile. Electrical contacts
have ceased to stick when thoroughly understood. Note the automatic telephone
exchange, which has hundreds of thousands of such contacts, and yet is
reliable. A spider web of metal, sealed in a thin glass container, a wire
heated to brilliant glow, in short, the thermionic tube of radio sets, is made
by the hundred million, tossed about in packages, plugged into sockets—and it
works! Its gossamer parts, the precise location and alignment involved in its
construction, would have occupied a master craftsman of the guild for months;
now it is built for thirty cents. The world has arrived at an age of cheap
complex devices of great reliability; and something is bound to come of it.
A record if it is to be useful to science, must be continuously extended, it
must be stored, and above all it must be consulted. Today we make the record
conventionally by writing and photography, followed by printing; but we also
record on film, on wax disks, and on magnetic wires. Even if utterly new
recording procedures do not appear, these present ones are certainly in the process of modification and extension.
Certainly progress in photography is not going to stop. Faster material and
lenses, more automatic cameras, finer-grained sensitive compounds to allow an
extension of the minicamera idea, are all imminent. Let us project this trend
ahead to a logical, if not inevitable, outcome. The camera hound of the future
wears on his forehead a lump a little larger than a walnut. It takes pictures 3
millimeters square, later to be projected or enlarged, which after all involves
only a factor of 10 beyond present practice. The lens is of universal focus,
down to any distance accommodated by the unaided eye, simply because it is of
short focal length. There is a built-in photocell on the walnut such as we now
have on at least one camera, which automatically adjusts exposure for a wide
range of illumination. There is film in the walnut for a hundred exposures, and
the spring for operating its shutter and shifting its film is wound once for
all when the film clip is inserted. It produces its result in full color. It may well be stereoscopic, and record with two spaced glass eyes, for striking
improvements in stereoscopic technique are just around the corner.
The cord which trips its shutter may reach down a man's sleeve within easy
reach of his fingers. A quick squeeze, and the picture is taken. On a pair of
ordinary glasses is a square of fine lines near the top of one lens, where it
is out of the way of ordinary vision. When an object appears in that square, it
is lined up for its picture. As the scientist of the future moves about the
laboratory or the field, every time he looks at something worthy of the record,
he trips the shutter and in it goes, without even an audible click. Is this all
fantastic? The only fantastic thing about it is the idea of making as many
pictures as would result from its use.
Will there be dry photography? It is already here in two forms. When Brady made
his Civil War pictures, the plate had to be wet at the time of exposure. Now it
has to be wet during development instead. In the future perhaps it need not be
wetted at all. There have long been films impregnated with diazo dyes which
form a picture without development, so that it is already there as soon as the
camera has been operated. An exposure to ammonia gas destroys the unexposed
dye, and the picture can then be taken out into the light and examined. The
process is now slow, but someone may speed it up, and it has no grain
difficulties such as now keep photographic researchers busy. Often it would be
advantageous to be able to snap the camera and to look at the picture
Another process now in use is also slow, and more or less clumsy. For fifty
years impregnated papers have been used which turn dark at every point where an
electrical contact touches them, by reason of the chemical change thus produced
in an iodine compound included in the paper. They have been used to make
records, for a pointer moving across them can leave a trail behind. If the
electrical potential on the pointer is varied as it moves, the line becomes
light or dark in accordance with the potential.
This scheme is now used in facsimile transmission. The pointer draws a set of
closely spaced lines across the paper one after another. As it moves, its
potential is varied in accordance with a varying current received over wires
from a distant station, where these variations are produced by a photocell
which is similarly scanning a picture. At every instant the darkness of the
line being drawn is made equal to the darkness of the point on the picture
being observed by the photocell. Thus, when the whole picture has been covered,
a replica appears at the receiving end.
A scene itself can be just as well looked over line by line by the photocell in
this way as can a photograph of the scene. This whole apparatus constitutes a
camera, with the added feature, which can be dispensed with if desired, of
making its picture at a distance. It is slow, and the picture is poor in
detail. Still, it does give another process of dry photography, in which the
picture is finished as soon as it is taken.
It would be a brave man who would predict that such a process will always
remain clumsy, slow, and faulty in detail. Television equipment today transmits
sixteen reasonably good pictures a second, and it involves only two essential
differences from the process described above. For one, the record is made by a
moving beam of electrons rather than a moving pointer, for the reason that an
electron beam can sweep across the picture very rapidly indeed. The other
difference involves merely the use of a screen which glows momentarily when the
electrons hit, rather than a chemically treated paper or film which is
permanently altered. This speed is necessary in television, for motion pictures
rather than stills are the object.
Use chemically treated film in place of the glowing screen, allow the apparatus
to transmit one picture only rather than a succession, and a rapid camera for
dry photography results. The treated film needs to be far faster in action than
present examples, but it probably could be. More serious is the objection that
this scheme would involve putting the film inside a vacuum chamber, for
electron beams behave normally only in such a rarefied environment. This
difficulty could be avoided by allowing the electron beam to play on one side
of a partition, and by pressing the film against the other side, if this
partition were such as to allow the electrons to go through perpendicular to
its surface, and to prevent them from spreading out sideways. Such partitions,
in crude form, could certainly be constructed, and they will hardly hold up the
Like dry photography, microphotography still has a long way to go. The basic
scheme of reducing the size of the record, and examining it by projection
rather than directly, has possibilities too great to be ignored. The
combination of optical projection and photographic reduction is already
producing some results in microfilm for scholarly purposes, and the
potentialities are highly suggestive. Today, with microfilm, reductions by a
linear factor of 20 can be employed and still produce full clarity when the
material is re-enlarged for examination. The limits are set by the graininess
of the film, the excellence of the optical system, and the efficiency of the
light sources employed. All of these are rapidly improving.
Assume a linear ratio of 100 for future use. Consider film of the same
thickness as paper, although thinner film will certainly be usable. Even under
these conditions there would be a total factor of 10,000 between the bulk of
the ordinary record on books, and its microfilm replica. The Encyclopoedia
Britannica could be reduced to the volume of a matchbox. A library of a million volumes could be compressed into one end of a desk. If the human race has produced since the invention of movable type a total record, in the form of
magazines, newspapers, books, tracts, advertising blurbs, correspondence,
having a volume corresponding to a billion books, the whole affair, assembled
and compressed, could be lugged off in a moving van. Mere compression, of
course, is not enough; one needs not only to make and store a record but also
be able to consult it, and this aspect of the matter comes later. Even the
modern great library is not generally consulted; it is nibbled at by a few.
Compression is important, however, when it comes to costs. The material for the
microfilm Britannica would cost a nickel, and it could be mailed anywhere for a cent. What would it cost to print a million copies? To print a sheet of newspaper, in a large edition, costs a small fraction of a cent. The entire material of the Britannica in reduced microfilm form would go on a sheet eight and one-half by eleven inches. Once it is available, with the photographic reproduction methods of the future, duplicates in large quantities could probably be turned out for a cent apiece beyond the cost of materials. The preparation of the original copy? That introduces the next aspect of the
To make the record, we now push a pencil or tap a typewriter. Then comes the
process of digestion and correction, followed by an intricate process of
typesetting, printing, and distribution. To consider the first stage of the
procedure, will the author of the future cease writing by hand or typewriter
and talk directly to the record? He does so indirectly, by talking to a
stenographer or a wax cylinder; but the elements are all present if he wishes
to have his talk directly produce a typed record. All he needs to do is to take
advantage of existing mechanisms and to alter his language.
At a recent World Fair a machine called a Voder was shown. A girl stroked its
keys and it emitted recognizable speech. No human vocal chords entered into the
procedure at any point; the keys simply combined some electrically produced
vibrations and passed these on to a loud-speaker. In the Bell Laboratories
there is the converse of this machine, called a Vocoder. The loudspeaker is
replaced by a microphone, which picks up sound. Speak to it, and the
corresponding keys move. This may be one element of the postulated system.
The other element is found in the stenotype, that somewhat disconcerting device
encountered usually at public meetings. A girl strokes its keys languidly and
looks about the room and sometimes at the speaker with a disquieting gaze. From
it emerges a typed strip which records in a phonetically simplified language a
record of what the speaker is supposed to have said. Later this strip is
retyped into ordinary language, for in its nascent form it is intelligible only
to the initiated. Combine these two elements, let the Vocoder run the
stenotype, and the result is a machine which types when talked to.
Our present languages are not especially adapted to this sort of mechanization,
it is true. It is strange that the inventors of universal languages have not
seized upon the idea of producing one which better fitted the technique for
transmitting and recording speech. Mechanization may yet force the issue,
especially in the scientific field; whereupon scientific jargon would become
still less intelligible to the layman.
One can now picture a future investigator in his laboratory. His hands are
free, and he is not anchored. As he moves about and observes, he photographs
and comments. Time is automatically recorded to tie the two records together.
If he goes into the field, he may be connected by radio to his recorder. As he
ponders over his notes in the evening, he again talks his comments into the
record. His typed record, as well as his photographs, may both be in miniature,
so that he projects them for examination.
Much needs to occur, however, between the collection of data and observations,
the extraction of parallel material from the existing record, and the final
insertion of new material into the general body of the common record. For
mature thought there is no mechanical substitute. But creative thought and
essentially repetitive thought are very different things. For the latter there
are, and may be, powerful mechanical aids.
Adding a column of figures is a repetitive thought process, and it was long ago
properly relegated to the machine. True, the machine is sometimes controlled by
a keyboard, and thought of a sort enters in reading the figures and poking the
corresponding keys, but even this is avoidable. Machines have been made which
will read typed figures by photocells and then depress the corresponding keys;
these are combinations of photocells for scanning the type, electric circuits
for sorting the consequent variations, and relay circuits for interpreting the
result into the action of solenoids to pull the keys down.
All this complication is needed because of the clumsy way in which we have
learned to write figures. If we recorded them positionally, simply by the
configuration of a set of dots on a card, the automatic reading mechanism would
become comparatively simple. In fact if the dots are holes, we have the
punched-card machine long ago produced by Hollorith for the purposes of the
census, and now used throughout business. Some types of complex businesses
could hardly operate without these machines.
Adding is only one operation. To perform arithmetical computation involves also
subtraction, multiplication, and division, and in addition some method for
temporary storage of results, removal from storage for further manipulation,
and recording of final results by printing. Machines for these purposes are now
of two types: keyboard machines for accounting and the like, manually
controlled for the insertion of data, and usually automatically controlled as
far as the sequence of operations is concerned; and punched-card machines in
which separate operations are usually delegated to a series of machines, and
the cards then transferred bodily from one to another. Both forms are very
useful; but as far as complex computations are concerned, both are still in
Rapid electrical counting appeared soon after the physicists found it desirable
to count cosmic rays. For their own purposes the physicists promptly
constructed thermionic-tube equipment capable of counting electrical impulses
at the rate of 100,000 a second. The advanced arithmetical machines of the
future will be electrical in nature, and they will perform at 100 times present
speeds, or more.
Moreover, they will be far more versatile than present commercial machines, so
that they may readily be adapted for a wide variety of operations. They will be
controlled by a control card or film, they will select their own data and
manipulate it in accordance with the instructions thus inserted, they will
perform complex arithmetical computations at exceedingly high speeds, and they
will record results in such form as to be readily available for distribution or
for later further manipulation. Such machines will have enormous appetites. One
of them will take instructions and data from a whole roomful of girls armed
with simple key board punches, and will deliver sheets of computed results
every few minutes. There will always be plenty of things to compute in the
detailed affairs of millions of people doing complicated things.
The repetitive processes of thought are not confined however, to matters of
arithmetic and statistics. In fact, every time one combines and records facts in accordance with established logical processes, the creative aspect of thinking is concerned only with the selection of the data and the process to be employed and the manipulation thereafter is repetitive in nature and hence a fit matter to be relegated to the machine. Not so much has been done along these lines,beyond the bounds of arithmetic, as might be done, primarily because of the economics of the situation. The needs of business and the extensive market obviously waiting, assured the advent of mass-produced arithmetical machines just as soon as production methods were sufficiently advanced.
With machines for advanced analysis no such situation existed; for there was
and is no extensive market; the users of advanced methods of manipulating data
are a very small part of the population. There are, however, machines for
solving differential equations—and functional and integral equations, for that
matter. There are many special machines, such as the harmonic synthesizer which
predicts the tides. There will be many more, appearing certainly first in the
hands of the scientist and in small numbers.
If scientific reasoning were limited to the logical processes of arithmetic, we
should not get far in our understanding of the physical world. One might as
well attempt to grasp the game of poker entirely by the use of the mathematics
of probability. The abacus, with its beads strung on parallel wires, led the
Arabs to positional numeration and the concept of zero many centuries before
the rest of the world; and it was a useful tool—so useful that it still
It is a far cry from the abacus to the modern keyboard accounting machine. It
will be an equal step to the arithmetical machine of the future. But even this
new machine will not take the scientist where he needs to go. Relief must be
secured from laborious detailed manipulation of higher mathematics as well, if
the users of it are to free their brains for something more than repetitive
detailed transformations in accordance with established rules. A mathematician
is not a man who can readily manipulate figures; often he cannot. He is not
even a man who can readily perform the transformations of equations by the use
of calculus. He is primarily an individual who is skilled in the use of
symbolic logic on a high plane, and especially he is a man of intuitive
judgment in the choice of the manipulative processes he employs.
All else he should be able to turn over to his mechanism, just as confidently
as he turns over the propelling of his car to the intricate mechanism under the
hood. Only then will mathematics be practically effective in bringing the
growing knowledge of atomistics to the useful solution of the advanced problems
of chemistry, metallurgy, and biology. For this reason there still come more
machines to handle advanced mathematics for the scientist. Some of them will be
sufficiently bizarre to suit the most fastidious connoisseur of the present
artifacts of civilization.
The scientist, however, is not the only person who manipulates data and
examines the world about him by the use of logical processes, although he
sometimes preserves this appearance by adopting into the fold anyone who
becomes logical, much in the manner in which a British labor leader is elevated
to knighthood. Whenever logical processes of thought are employed—that is,
whenever thought for a time runs along an accepted groove—there is an
opportunity for the machine. Formal logic used to be a keen instrument in the
hands of the teacher in his trying of students' souls. It is readily possible
to construct a machine which will manipulate premises in accordance with formal
logic, simply by the clever use of relay circuits. Put a set of premises into
such a device and turn the crank, and it will readily pass out conclusion after
conclusion, all in accordance with logical law, and with no more slips than
would be expected of a keyboard adding machine.
Logic can become enormously difficult, and it would undoubtedly be well to
produce more assurance in its use. The machines for higher analysis have
usually been equation solvers. Ideas are beginning to appear for equation
transformers, which will rearrange the relationship expressed by an equation in
accordance with strict and rather advanced logic. Progress is inhibited by the
exceedingly crude way in which mathematicians express their relationships. They
employ a symbolism which grew like Topsy and has little consistency; a strange
fact in that most logical field.
A new symbolism, probably positional, must apparently precede the reduction of
mathematical transformations to machine processes. Then, on beyond the strict
logic of the mathematician, lies the application of logic in everyday affairs.
We may some day click off arguments on a machine with the same assurance that
we now enter sales on a cash register. But the machine of logic will not look
like a cash register, even of the streamlined model.
So much for the manipulation of ideas and their insertion into the record. Thus
far we seem to be worse off than before—for we can enormously extend the
record; yet even in its present bulk we can hardly consult it. This is a much
larger matter than merely the extraction of data for the purposes of scientific
research; it involves the entire process by which man profits by his
inheritance of acquired knowledge. The prime action of use is selection, and
here we are halting indeed. There may be millions of fine thoughts, and the
account of the experience on which they are based, all encased within stone
walls of acceptable architectural form; but if the scholar can get at only one
a week by diligent search, his syntheses are not likely to keep up with the
Selection, in this broad sense, is a stone adze in the hands of a cabinetmaker.
Yet, in a narrow sense and in other areas, something has already been done
mechanically on selection. The personnel officer of a factory drops a stack of
a few thousand employee cards into a selecting machine, sets a code in
accordance with an established convention, and produces in a short time a list
of all employees who live in Trenton and know Spanish. Even such devices are
much too slow when it comes, for example, to matching a set of fingerprints
with one of five million on file. Selection devices of this sort will soon be
speeded up from their present rate of reviewing data at a few hundred a minute.
By the use of photocells and microfilm they will survey items at the rate of a
thousand a second, and will print out duplicates of those selected.
This process, however, is simple selection: it proceeds by examining in turn
every one of a large set of items, and by picking out those which have certain
specified characteristics. There is another form of selection best illustrated
by the automatic telephone exchange. You dial a number and the machine selects
and connects just one of a million possible stations. It does not run over them
all. It pays attention only to a class given by a first digit, then only to a
subclass of this given by the second digit, and so on; and thus proceeds
rapidly and almost unerringly to the selected station. It requires a few
seconds to make the selection, although the process could be speeded up if
increased speed were economically warranted. If necessary, it could be made
extremely fast by substituting thermionic-tube switching for mechanical
switching, so that the full selection could be made in one one-hundredth of a
second. No one would wish to spend the money necessary to make this change in
the telephone system, but the general idea is applicable elsewhere.
Take the prosaic problem of the great department store. Every time a charge
sale is made, there are a number of things to be done. The inventory needs to
be revised, the salesman needs to be given credit for the sale, the general
accounts need an entry, and, most important, the customer needs to be charged.
A central records device has been developed in which much of this work is done
conveniently. The salesman places on a stand the customer's identification
card, his own card, and the card taken from the article sold—all punched
cards. When he pulls a lever, contacts are made through the holes, machinery at
a central point makes the necessary computations and entries, and the proper
receipt is printed for the salesman to pass to the customer.
But there may be ten thousand charge customers doing business with the store,
and before the full operation can be completed someone has to select the right
card and insert it at the central office. Now rapid selection can slide just
the proper card into position in an instant or two, and return it afterward.
Another difficulty occurs, however. Someone must read a total on the card, so
that the machine can add its computed item to it. Conceivably the cards might
be of the dry photography type I have described. Existing totals could then be
read by photocell, and the new total entered by an electron beam.
The cards may be in miniature, so that they occupy little space. They must move
quickly. They need not be transferred far, but merely into position so that the
photocell and recorder can operate on them. Positional dots can enter the data.
At the end of the month a machine can readily be made to read these and to
print an ordinary bill. With tube selection, in which no mechanical parts are
involved in the switches, little time need be occupied in bringing the correct
card into use—a second should suffice for the entire operation. The whole
record on the card may be made by magnetic dots on a steel sheet if desired,
instead of dots to be observed optically, following the scheme by which Poulsen
long ago put speech on a magnetic wire. This method has the advantage of
simplicity and ease of erasure. By using photography, however one can arrange
to project the record in enlarged form and at a distance by using the process
common in television equipment.
One can consider rapid selection of this form, and distant projection for other
purposes. To be able to key one sheet of a million before an operator in a
second or two, with the possibility of then adding notes thereto, is suggestive
in many ways. It might even be of use in libraries, but that is another story.
At any rate, there are now some interesting combinations possible. One might,
for example, speak to a microphone, in the manner described in connection with
the speech controlled typewriter, and thus make his selections. It would
certainly beat the usual file clerk.
The real heart of the matter of selection, however, goes deeper than a lag in
the adoption of mechanisms by libraries, or a lack of development of devices for their use. Our ineptitude in getting at the record is largely caused by
the artificiality of systems of indexing. When data of any sort are placed in
storage, they are filed alphabetically or numerically, and information is found
(when it is) by tracing it down from subclass to subclass. It can be in only
one place, unless duplicates are used; one has to have rules as to which path
will locate it, and the rules are cumbersome. Having found one item, moreover,
one has to emerge from the system and re-enter on a new path.
The human mind does not work that way. It operates by association. With one
item in its grasp, it snaps instantly to the next that is suggested by the
association of thoughts, in accordance with some intricate web of trails
carried by the cells of the brain. It has other characteristics, of course;
trails that are not frequently followed are prone to fade, items are not fully
permanent, memory is transitory. Yet the speed of action, the intricacy of
trails, the detail of mental pictures, is awe-inspiring beyond all else in
Man cannot hope fully to duplicate this mental process artificially, but he
certainly ought to be able to learn from it. In minor ways he may even improve,
for his records have relative permanency. The first idea, however, to be drawn
from the analogy concerns selection. Selection by association, rather than
indexing, may yet be mechanized. One cannot hope thus to equal the speed and
flexibility with which the mind follows an associative trail, but it should be
possible to beat the mind decisively in regard to the permanence and clarity of
the items resurrected from storage.
Consider a future device for individual use, which is a sort of mechanized private file and library. It needs a name, and, to coin one at random, "memex" will do. A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory.
It consists of a desk, and while it can presumably be operated from a distance,
it is primarily the piece of furniture at which he works. On the top are
slanting translucent screens, on which material can be projected for convenient
reading. There is a keyboard, and sets of buttons and levers. Otherwise it
looks like an ordinary desk.
In one end is the stored material. The matter of bulk is well taken care of by
improved microfilm. Only a small part of the interior of the memex is devoted
to storage, the rest to mechanism. Yet if the user inserted 5000 pages of
material a day it would take him hundreds of years to fill the repository, so
he can be profligate and enter material freely.
Most of the memex contents are purchased on microfilm ready for insertion.
Books of all sorts, pictures, current periodicals, newspapers, are thus
obtained and dropped into place. Business correspondence takes the same path.
And there is provision for direct entry. On the top of the memex is a
transparent platen. On this are placed longhand notes, photographs, memoranda,
all sorts of things. When one is in place, the depression of a lever causes it
to be photographed onto the next blank space in a section of the memex film,
dry photography being employed.
There is, of course, provision for consultation of the record by the usual
scheme of indexing. If the user wishes to consult a certain book, he taps its
code on the keyboard, and the title page of the book promptly appears before
him, projected onto one of his viewing positions. Frequently-used codes are
mnemonic, so that he seldom consults his code book; but when he does, a single
tap of a key projects it for his use. Moreover, he has supplemental levers. On
deflecting one of these levers to the right he runs through the book before
him, each page in turn being projected at a speed which just allows a
recognizing glance at each. If he deflects it further to the right, he steps
through the book 10 pages at a time; still further at 100 pages at a time.
Deflection to the left gives him the same control backwards.
A special button transfers him immediately to the first page of the index. Any
given book of his library can thus be called up and consulted with far greater
facility than if it were taken from a shelf. As he has several projection
positions, he can leave one item in position while he calls up another. He can
add marginal notes and comments, taking advantage of one possible type of dry
photography, and it could even be arranged so that he can do this by a stylus
scheme, such as is now employed in the telautograph seen in railroad waiting
rooms, just as though he had the physical page before him.
All this is conventional, except for the projection forward of present-day
mechanisms and gadgetry. It affords an immediate step, however, to associative
indexing, the basic idea of which is a provision whereby any item may be caused
at will to select immediately and automatically another. This is the essential
feature of the memex. The process of tying two items together is the important
When the user is building a trail, he names it, inserts the name in his code
book, and taps it out on his keyboard. Before him are the two items to be
joined, projected onto adjacent viewing positions. At the bottom of each there
are a number of blank code spaces, and a pointer is set to indicate one of
these on each item. The user taps a single key, and the items are permanently
joined. In each code space appears the code word. Out of view, but also in the
code space, is inserted a set of dots for photocell viewing; and on each item
these dots by their positions designate the index number of the other item.
Thereafter, at any time, when one of these items is in view, the other can be
instantly recalled merely by tapping a button below the corresponding code
space. Moreover, when numerous items have been thus joined together to form a
trail, they can be reviewed in turn, rapidly or slowly, by deflecting a lever
like that used for turning the pages of a book. It is exactly as though the
physical items had been gathered together from widely separated sources and
bound together to form a new book. It is more than this, for any item can be
joined into numerous trails.
The owner of the memex, let us say, is interested in the origin and properties
of the bow and arrow. Specifically he is studying why the short Turkish bow was
apparently superior to the English long bow in the skirmishes of the Crusades.
He has dozens of possibly pertinent books and articles in his memex. First he
runs through an encyclopedia, finds an interesting but sketchy article, leaves
it projected. Next, in a history, he finds another pertinent item, and ties the
two together. Thus he goes, building a trail of many items. Occasionally he
inserts a comment of his own, either linking it into the main trail or joining
it by a side trail to a particular item. When it becomes evident that the
elastic properties of available materials had a great deal to do with the bow,
he branches off on a side trail which takes him through textbooks on elasticity
and tables of physical constants. He inserts a page of longhand analysis of his
own. Thus he builds a trail of his interest through the maze of materials
available to him.
And his trails do not fade. Several years later, his talk with a friend turns
to the queer ways in which a people resist innovations, even of vital interest.
He has an example, in the fact that the outraged Europeans still failed to
adopt the Turkish bow. In fact he has a trail on it. A touch brings up the code
book. Tapping a few keys projects the head of the trail. A lever runs through
it at will, stopping at interesting items, going off on side excursions. It is
an interesting trail, pertinent to the discussion. So he sets a reproducer in
action, photographs the whole trail out, and passes it to his friend for
insertion in his own memex, there to be linked into the more general trail.
Wholly new forms of encyclopedias will appear, ready made with a mesh of
associative trails running through them, ready to be dropped into the memex and
there amplified. The lawyer has at his touch the associated opinions and
decisions of his whole experience, and of the experience of friends and
authorities. The patent attorney has on call the millions of issued patents,
with familiar trails to every point of his client's interest. The physician,
puzzled by a patient's reactions, strikes the trail established in studying an
earlier similar case, and runs rapidly through analogous case histories, with
side references to the classics for the pertinent anatomy and histology. The
chemist, struggling with the synthesis of an organic compound, has all the
chemical literature before him in his laboratory, with trails following the
analogies of compounds, and side trails to their physical and chemical
The historian, with a vast chronological account of a people, parallels it with
a skip trail which stops only on the salient items, and can follow at any time
contemporary trails which lead him all over civilization at a particular epoch.
There is a new profession of trail blazers, those who find delight in the task
of establishing useful trails through the enormous mass of the common record.
The inheritance from the master becomes, not only his additions to the world's
record, but for his disciples the entire scaffolding by which they were
Thus science may implement the ways in which man produces, stores, and consults
the record of the race. It might be striking to outline the instrumentalities
of the future more spectacularly, rather than to stick closely to methods and
elements now known and undergoing rapid development, as has been done here.
Technical difficulties of all sorts have been ignored, certainly, but also
ignored are means as yet unknown which may come any day to accelerate technical
progress as violently as did the advent of the thermionic tube. In order that
the picture may not be too commonplace, by reason of sticking to present-day
patterns, it may be well to mention one such possibility, not to prophesy but
merely to suggest, for prophecy based on extension of the known has substance,
while prophecy founded on the unknown is only a doubly involved guess.
All our steps in creating or absorbing material of the record proceed through
one of the senses—the tactile when we touch keys, the oral when we speak or
listen, the visual when we read. Is it not possible that some day the path may
be established more directly?
We know that when the eye sees, all the consequent information is transmitted
to the brain by means of electrical vibrations in the channel of the optic
nerve. This is an exact analogy with the electrical vibrations which occur in
the cable of a television set: they convey the picture from the photocells
which see it to the radio transmitter from which it is broadcast. We know
further that if we can approach that cable with the proper instruments, we do
not need to touch it; we can pick up those vibrations by electrical induction
and thus discover and reproduce the scene which is being transmitted, just as
a telephone wire may be tapped for its message.
The impulses which flow in the arm nerves of a typist convey to her fingers the
translated information which reaches her eye or ear, in order that the fingers
may be caused to strike the proper keys. Might not these currents be
intercepted, either in the original form in which information is conveyed to
the brain, or in the marvelously metamorphosed form in which they then proceed
to the hand?
By bone conduction we already introduce sounds: into the nerve channels of the
deaf in order that they may hear. Is it not possible that we may learn to
introduce them without the present cumbersomeness of first transforming
electrical vibrations to mechanical ones, which the human mechanism promptly
transforms back to the electrical form? With a couple of electrodes on the
skull the encephalograph now produces pen-and-ink traces which bear some
relation to the electrical phenomena going on in the brain itself. True, the
record is unintelligible, except as it points out certain gross misfunctioning
of the cerebral mechanism; but who would now place bounds on where such a thing
In the outside world, all forms of intelligence whether of sound or sight, have
been reduced to the form of varying currents in an electric circuit in order
that they may be transmitted. Inside the human frame exactly the same sort of
process occurs. Must we always transform to mechanical movements in order to
proceed from one electrical phenomenon to another? It is a suggestive thought,
but it hardly warrants prediction without losing touch with reality and
Presumably man's spirit should be elevated if he can better review his shady
past and analyze more completely and objectively his present problems. He has
built a civilization so complex that he needs to mechanize his records more
fully if he is to push his experiment to its logical conclusion and not merely
become bogged down part way there by overtaxing his limited memory. His
excursions may be more enjoyable if he can reacquire the privilege of
forgetting the manifold things he does not need to have immediately at hand,
with some assurance that he can find them again if they prove important.
The applications of science have built man a well-supplied house, and are
teaching him to live healthily therein. They have enabled him to throw masses
of people against one another with cruel weapons. They may yet allow him truly
to encompass the great record and to grow in the wisdom of race experience. He
may perish in conflict before he learns to wield that record for his true good.
Yet, in the application of science to the needs and desires of man, it would
seem to be a singularly unfortunate stage at which to terminate the process, or
to lose hope as to the outcome.
Volume 176, No. 1, pp. 101–108