of equivalent invention. If a revised edition of each article were to be published today, there would be few words requiring change.

Prediction in Various Special Fields

Some brief examinations of the success of prediction generally in certain special fields-military, airplanes, radio, and television should be instructive. These categories have not been covered fully enough for statistical analysis to be used. Rather, this review is intended to give a general idea of how prediction has gone, why it has been more successful in certain fields and by certain kinds of seers than by others, and how it might have been done much better, had the most capable predictors been fully awake to the latest developments and thought of their time and of one another.

In the forecasting of military inventions, what is striking is the usual poor success of those who published. H. G. Wells claims an exception for Bloch, a Polish banker who, in 1897, predicted that war must lead to a deadlock of trenches, and of economic exhaustion, such as did arrive for Central and Eastern Europe after 3 or 4 years' fighting.12 His predictions in more detail were largely mistaken. Wells' revision of 1902 was a more successful study. It seems that the military arts are so progressive, and the value and possibility of invention so well recognized (despite claims that all revolutionary military inventions have been made by civilians), and the latest developments and projects are held so closely secret, that it is impossible for an outside author to outguess the silent inside experts, unless he ranges far into the future.

Thus, a humorous French article 13 of 1883 did succeed in predicting tanks, gas shells and masks, liquid fire, mine-laying by submarines, railway guns, the importance of artillery, dirigibles, airplanes, air torpedoes, anti-aircraft artillery and observation posts, and telephoning from an airplane by a trailing wire, which can be done if the airplane circles about. In short, this article foretold about all the novel implements of the war 35 years later.

The airplane has had no lack of forward-looking inventors since the first attempts in the Middle Ages, on through Ader 14 who flew 50 meters in 1890, and was then financed for 6 years by the French Army, down to the definite success of the Wrights in 1903.

12 A summary volume entitled The Future of War in its technical, economic, and political relations, translated by R. C. Long, was published in New York in 1899.

13 By Robida, artist and editor of La Caricature, in the same for Oct. 27, 1883; reviewed as the Jules Verne of Caricature, in New France, 2: 107-110, June 1918.

14 Clément Ader: La Première étape de l'aviation militaire en France. 1907.

The guesses of the early aviation enthusiasts, e. g., Baden-Powell, as to types, dates of success, speeds to be attained, and uses for flying, seem to have been about right, while as much cannot be said for the professional predictors, in the decade when airplanes were just beginning to fly. Fair forecasts of the present of aviation and its uses were made by the specially informed Kaempffert in 1911.15

Wireless telegraphy, or at least the transmission of electric shocks through a body of water, or by conduction or induction, is nigh 2 centuries old, and was practiced for communication by Morse in 1842. Wireless telephony by electromagnetic waves was observed in 1884.16 The familiar radio waves were suggested for communication by Elihu Thompson in 1889, the year after Hertz first detected them. Presently, Crookes proposed the same. About that time Sylvanus Thompson offered for £10,000 to establish communication by induction with South Africa. So there has been no lack of suggestions for the forecasters, long before wireless telegraphy burst on the world about 1900, and radiotelephony in 1922. Sutherland in 1900 proposed, as has been noted, radio control of clocks (an invention which various manufacturers are racing to realize today) and radiotelephony.

Dr.

Telephony with Hertzian waves, our own radio, was first achieved by Fessenden in 1900, and on Christmas Eve of 1906 he broadcast music, and the next year speech clearly over 200 miles. DeForest at the same time broadcast Caruso singing, and the ethereal music of the telharmonium. But in an article wherein Fessenden discussed well the uses of point-to-point wireless telephony, he did not mention broadcasting. There were very few others who thought of it until the opening of KDKA on election night, 1920.17 Frank Conrad had begun broadcasting soon after the war, leading to the establishment of this first regular station by Westinghouse, the furor over radio in 1922, and the fixing of program principles since followed. In fact we see that while radiotelephony was early foreseen and used, the possibility of its broadcast use was strangely overlooked by almost all people. Probably it was because they could not imagine the receiving apparatus as simple and cheap enough. It is hard

15 Waldemar Kaempffert: The New Art of Flying, New York, April 1911. The Future of Flying; in Country Life, 20: 23 ff., July 15, 1911. Aircraft and the Future; in Outlook, 104: 452-460, 1913.

16 Sir W. H. Preece: Signaling Through Space Without Wires; in Smithson. Instn. An. Rept. for 1898, pp. 249-257, esp. 251. He later telephoned a mile by this means, and 3 miles by conduction, while wireless telephony by induction was realized by another contemporary. Cf. Sylvanus P. Thompson: Telegraphing Across Space; in the same, pp. 235-246. Thompson in 1898 was certain that wireless communication between England and America could be established either by conduction or by induction; as to radio he was less sure.

17 Wireless Telephony; in Smithson. Instn. An. Rept. for 1908, pp. 161-195.

to find a prophet other than Steinmetz who mentioned it. But many predicted the same result by other means, and there was commercial telephone broadcasting from 1889.

Television has had a much more common and early prediction, though not achieved till 1911. (But its slow form, picture telegraphy, dates from 1847.) Souvestre 18 satirically foretold it in 1846, Senlecq 19 built an apparatus in 1877, only 4 years after the discovery that selenium varies in conductivity according to its illumination. Nipkow invented the scanning disk in 1882 and Fessenden designed a wireless system in 1901.19 Plessner 20 in 1892 wrote a book about the possibilities of this and other future communication devices, proposing ways to combine television with the telephone for wired broadcasting, and to broadcast motion pictures, and use sound-film, picture, and facsimile telegraphy. To the uses which he foresaw for television we can add little further today, except to show the animated cartoon and its scientific brothers, the animated diagram and drawing. T. B. Russell, the present writer, and so many other forecasters have likewise talked of television, that it is hard to add anything new on the subject of this invention whose effective realization has scarce begun.

From our survey of prediction in the four fields above as well as in others, the following conclusions may be drawn:

1. War has been an unfavorable field for outside predictors, while transportation, communication, and optics seem unusually full of successes.

2. Those undertaking general prophecy have not written in the scientific manner. But no reason appears why one should not use science in estimating the future, as in any other business. A scientific worker would diligently study both the past and latest inventive developments, and comb all the best opinions and guesses about the future, in whatever language published.28 Furthermore he would study, criticize, and improve the technique of prediction, from the evidence of past success and failure in foresight. At least no reason appears against predictive science, except the cost of labor, and the difficulty of finding special students of this field who have some acquaintance with all branches of technology and their history, and with social science, and languages.

3. Inventors are necessarily forecasters, but are rather mute aside from their own projects.

4. Distinguished technical and scientific men, who choose to predict in their own general field, make the best seers of all. Yet they are liable to upsets from

18 Emile Souvestre: Le Monde tel qu'il sera (in the year 3000). 19 Sci. Am., Mar. 8, 1879; S. A. Sup., 11:4382, 1881. C. Senlecq Le Télectroscope, 1881. R. Fessenden: The Deluged Civilization, p. 123 ff. 20 Max Plessner: ein Blick auf die grossen Erfindungen des 20. Jahrhunderts. Ferd. Dümmlers Verlagsbuchhandlung, Berlin, 1892. 92 pp.

developments in outside lines, and from the tendency of the ordinary scientific or technical man to see little change ahead. For these are usually much impressed with the failure of all past inventors to achieve this and that, because of supposed scientific principles that bar the path.

5. A broad view, considering every quarter from which change could come, is clearly called for.

6. There seems to be a clear case for a committee of technical men uniting their labors, together with those of social scientists and students of prediction. This has been the basic assumption underlying the arrangement of this present volume.

Why and How Invention Is Predicted

Having pointed out, from experience, that inventions can be predicted and have been 15 and more years ahead of their effective use, it would seem wise to examine the reasons why this is possible, as well as the methods of prediction that are and should be used.

Inventions can first of all be predicted because they form trends, which can be projected into the future, extrapolated as the statistician says. An important invention, like the airplane or television, is not the product of one inventive act by one heroic, titular inventor at one date. Instead that great invention is an agglomeration of a vast number of detail inventions, like the thousands that have been added to the auto. Some are inventions no longer used, like the scanning disk that for 50 years built up television. The multiplicity of these inventions brings in the law of large numbers, making possible statistics, and the predictive extrapolation of a curve. Just as a merchant whose figures show a steady growth of his business expects still more business in the future, so when we see patents piled ever thicker upon food syntheses, or see aircraft capable of landing in less and less space, or television screens growing larger and finer, we readily, confidently, and justifiedly project these trends forward a short way into the future. This is the favorite method of the more technical writers, such as in the first article quoted, and appears to give the best results for short prognostications.

As a corollary of this principle that an invention of importance is a multitudinous collection of little ones, we observe that the first start in a new line practically never brings immediate success; that many further inventions, many years and decades, and many inventors must be added to the first before full success and wide use, bearing social consequences, will be attained. This makes much easier the range of prediction commonly attempted in this volume. One sets down for the future certain inventions already started. We have seen how television began to be invented in 1877, picture telegraphy about 88 years before it attained important

use, wireless 15 to 70 years, radiotelephony 23, the airplane 70 or more and the talking picture 40 years, before they had any importance.

Taking 19 inventions voted most useful, introduced in 1888-1913, the average 21 intervals were: Between when the invention was first merely thought of, and the first working model or patent, 176 years; thence to the first practical use, 24 years; to commercial success 14 years; to important use 12 years, or say 50 years from the first serious work on the invention. Again, in the study of the most important inventions of the last generation before 1930, in Recent Social Trends, a median lapse was found of 33 years, between the "conception date" corresponding to the second above, and the date of commercial success.22 Searching for exceptions, it is hardly possible to find an invention which became important in less than 10 years from the time it or some fully equivalent substitute was worked on, and few did in less than 20. Here is then, an excellent rule of prediction for the present study-to predict only inventions already born, whose physical possibility has therefore been demonstrated, but which are usually not yet practical, and whose future significance is not commonly appreciated.

This is very different from predicting future success for all present embryonic inventions. Their death rate is high-most will never be any good, like the eleven remarkable ship and engine projects of 1882, with which Admiral Preble closed his history, none of which has ever got anywhere, save for the modest success of the electric launch.

It may be useful to point out that a great reason why inventions progress so slowly through their incubating stage is that our laws provide no effective support for inventors who make basic starts in new lines. Let us cite two typical fundamentally novel inventions. A voice-operated writing machine was proposed in detail by Plessner in 1892 and Fessenden in 1907. Flowers 23 in 1916 made several such machines that would work after a fashion. But we hear of no other inventors trying to perfect the invention. Everybody's business is nobody's business, when no one can justifiedly hope to be repaid for the labor which will undoubtedly be required in perfecting the invention. An inventor may advance an embryonic art most usefully; but he can hardly advance it to the point of wide practical use, and hence he receives no recompense at all. For another example, the helicopter is needed for vertical or hovering flight, and for landing on ships, roofs, and rough places. People have been working since Leo

21 Gilfillan: Sociology of Invention, p. 96, from Sci. Am. 109: 352. See note 24.

22 Recent Sccial Trends in the United States, 1: 163.

23 John B. Flowers' inventions are described in Sci. Am., Feb. 12, 1916, p. 174; and Fessenden's cited in R. Fessenden: The Deluged Civilization, p. 134.

nardo da Vinci on this costly device. Some have even been flown, but no one has received a dollar of recompense except occasionally from a philanthropist or a government. Pioneer invention in new basic lines needs noncommercial support exactly as pure science does. France does a little to support and guide such inventors, through its Office National des Recherches et Inventions, and we have a few foundations that do something, but the costly starting of fundamental inventions is virtually unassisted, hence very slow.24

The second basic reason why inventions can be predicted is that they have causes. They are not just accidents, nor the inscrutable products of sporadic genius, but have abundant and clear causes in prior scientific and technological development. And they have social causes and retarding factors, both new and constant, of changed needs and opportunities, growth of technical education, of buying power, of capital, patent and commercial systems, corporation laboratories, and what not.25 All such basic factors causing invention give means of predicting the same.

The existence and overwhelming influence of causes for invention is proved by the frequency of duplicate invention, where the same idea is hatched by different minds independently about the same time. Professor Ogburn and Dr. Thomas have drawn up a list of 40 such duplicated inventions and 108 discoveries." Striking proof is offered by American patent office experience in that about half of all inventions that pass the already advanced stage of patent application are thereafter dropped, mainly because of the discovery of prior inventors, not to mention the number dropped for this reason at earlier stages. Inventors are constantly advised to keep proofs of their priority, their dates of conception. Dr. Stern has well demonstrated the abundance of duplicate discovery in medicine.27 And certainly the observations of duplicate invention would be much more numerous than they are, did not the published fact that an invention is made, prevent others from thinking up the same thing. It is only where the two inventors worked at almost the same time, or in remote isolation from each other, that we ever hear of the invention as being duplicated.

Having thus shown by the observed and potential frequency of duplicate invention that invention has widespread causes, not confined to the genius or luck of a single, indispensable inventor, it remains to show how this wide, causative base can be used for the prediction of an invention. And this we have not learned to do scientifically. The influences from need and pos

24 S. C. Gilfillan: The Sociology of Invention. Follett Pub. Co., Chicago, 1935; 203 pp. Ch. 5, The Hard Starting of Fundamental Inventions.

S. C. Gilfillan: The Sociology of Invention.

26 William F. Ogburn: Social Change, pt. 2, ch. 5.
Bernhard Stern: Social Factors in Medical Progress, 1927.

sibility that point to a coming invention are so exceedingly varied in nature that it is difficult to know how to generalize about them. But everyone knows how to use them, how to reason from such bases. We say that a given situation would naturally produce a certain adaptive step, either at once, or after a certain cultural lag or delay.

For instance, we would predict the early arrival, probably within 5 or 10 years, of a stereoscopic sound effect or auditory perspective, in the radio and perhaps in phonographs and talking pictures, from the following reasoning: A need has long existed for a means of varying the direction from which sound comes, so as to give an impression of solid space, and to facilitate understanding. This need has been increased by the talking picture, the loud speaker for the deaf, the flying and detection of airplanes in fog, and presently and especially, by radio television plays. There are established trends toward better and more complicated acoustical apparatus, and a rapid growth of acoustical science, and of devices for aviation and the deaf. Fairly simple means of achieving stereoscopic sound are readily imagined, and have already been built. The resistances to popularizing and perfecting the invention are a small cost, met by a growing income; unfamiliarity and complexity, met by growing popular knowledge of physics and especially acoustics. There are also the difficulty of making over old radio sets, etc., met by the approaching need to replace them anyway for purposes of television and ⚫perhaps other innovations, the need of standardization met by the capacity of our interstate laws, and the high degree of patent monopoly in these industries. In short the track is clear for this invention.

One may note that in the above reasoning use has been made of unchanging facts, such as knowledge of magnetism; recently changed facts, such as the starting of the invention in question; assumed future events, as the coming of television; numerous trends, as toward more acoustical knowledge; influences from diverse fields-deafness, aviation and war; obstructions; and opportunities.

This complex type of prediction based on reasoning as to causation, as well as on extrapolation of various trends, is evidently far more complicated than the empirical type of prediction discussed before, based simply on the extrapolation of one observed trend. Complication makes it much the less reliable, for the short range, although the evidence may be very strong, as for stereoscopic sound. But the empirical trend method may be inapplicable, from the absence of any direct trend. In the present case, e. g., we may not know that the invention has been put to use at all, so could not establish any trend of usage.

For a longer range forecasting the complex type may be much better than the simple projection of a single trend. For any curve becomes more and more uncertain the farther it is extrapolated into the future, for geometric reasons; and trends seemingly secure, may be upset by interference from outside. For example, in 1913 the designing of bigger and bigger liners seemed a well established and secure prediction, yet because of progress in aviation and railways there was predicted a cessation of the trend about 1929. The prediction has proved to be partially correct, as explained in the previous section.

If the inferences from numerous trends and other facts converge to the same conclusion, one may be more confident one is right. If the indications be somewhat contradictory we must express doubt, or make our prediction conditional, or make none, while still perhaps predicting social effects, for reasons given hereafter. Difficulties of Prediction

The most persistent danger, in the perilous business of forecasting, is what might be called a third regular method of prediction, to wit, sheer optimism. “Have faith, believe that what is good shall come to pass, and it shall be so" is offered us as a more or less religious motto, not only for the individual, but for society. And as Caesar long ago remarked, for the most part what men desire they believe to be easy. Man's mind normally works optimistically, save when he is out of sorts. A vast deal of utopian prophesying of the fine days to come, like Bellamy's Looking Backward, has been little more than optimism, future music. And even the best of prophets are continually beset by wishful thinking, predicting much more of good than of evil, partly because their readers will wish to hear of pleasant things. We need wireless power, or popular enlightenment, or rational costume, therefore some inventions will bring them. This method of prophecy is most unreliable; yet it has often produced good single predictions, since these were made in an age of advancing civilization, and what the predictor desired, say faster airplanes, or color movies, many inventors and their backers also wanted, and by setting themselves to discover it, satisfied at least two conditions for success-effort, with a receptive market.

Another variety of wishful thinking is overlooking the fact that the social basis for invention provides obstacles to it as well as incitements and facilities. There are all the resistances discussed in the accompanying papers against making an invention or accepting it after it is made.

While there are numerous resistances on grounds other than economics, the question of how technolog

ical changes are to be paid for is a preeminent one. Inventions may be blocked not only because they devaluate the capital and knowledge directly concerned in that line, but also because they devaluate the accessory capital. Thus trains and tracks are tied together, so there is no future for the monorail car nor any other device that would call for rebuilding our railroads, and even electrification is held back by the great costs involved. Simply faster trains call for track improvements that cannot well be provided, so speeding can be accepted only if the train can be made much lighter. Three other aspects of the world into which inventions must fit if accepted are tastes, customs, and laws, all very resistant to called-for changes. The sodium and mercury lamps are very efficient, but people don't like their respective yellow and blue lights. The telharmonium can play more beautiful music than was ever heard before, in the just intonation instead of the false, tempered intonation which all present instruments use by necessity. But to make the best use of the telharmonium will call for recomposing our music. Meals from central kitchens, perhaps delivered at high speed by pneumatic tubes which could serve many other purposes too, would eliminate much toil. But people like to do things their own way, which is an old way, so this prediction made in 1912 shows little progress toward fulfillment. The lie detector, universal fingerprinting, and various psychological and psychiatric discoveries, would be wonderful helps in the prevention of crime and the rehabilitation or permanent removal of criminals. But all such changes run up against the conservatism of the law. Lawyers are apt to be conservative, objecting to changes not only when they prejudice a client, but by natural tendency because their professional business is to interpret the law as it stands.

Predictors are often right that an invention can and will be made and will also be appreciated, but they still go wrong as to when, because they are too optimistic as to the reductions of cost, or of complexity. Color photography is a most attractive and valuable art that has existed for three-quarters of a century, and still it is little used except by a few professionals. The home talking picture, long predicted, is only beginning to find many buyers who are willing to pay its cost. The substitute means of entertainment or instruction are so simply and cheaply available-books, pictures, and the theater.

Advertisements tell us we can pick up our telephone and talk across the ocean to any subscriber in Hungary or Java, but for practical purposes that is impossible, because we have not the money, language, nor any need to make such calls. At any rate, hardly one in a million has, so the invention of transoceanic telephony to such countries does not yet exist as a factor of influence.

The dates of future inventions or of their use are indeed difficult to predict, because they depend on the total balance of so many separate considerations of technical difficulties, cost, usefulness, and the progress of substitutes. The stereoscopic and full-color home talking picture, with auditory perspective, could be made today and will surely come; but when will it be important?

The question is usually dodged by leaving the prediction dateless. But in a study like the present one, which aims at guidance for practical measures to meet impending situations, dating cannot be dodged. One may, however, get along with much uncertainty of dating, in two ways. First, if we know what to expect some time within the next generation, say the destruction of a certain trade, or the airplane bringing diseases in 18 hours from Africa, we may be prepared to take immediate practical steps whenever the first definite dating becomes possible, the better because we were predictively prepared beforehand. Secondly, we may be quite wrong in our prediction that such airplanes will be practical and common in 1945, and still be right in what essentially matters of our prediction, viz., that in 1945 yellow fever or other diseases will be brought amongst us from Africa and points east and west, by either airplanes, airships, helicopters, rockets, or some other means of fast traffic.

When Thurston, a good historian-engineer, predicted in 1893 that the speeds of the then 5-day liner and 20-hour New York-Chicago train would be doubled in the next generation, he was wrong—the ships sped hardly faster, and those fastest trains made the trip in the same time in 1923. But if he had made his prophecy more general by saying that through various means, traffic speeds would increase markedly, he would have been right, through the speeding up of the slow trains and ships and through the auto and airplane. We shall speak later of this principle of functionally equivalent invention, which is so helpful in predicting the consequences of invention.

Another error of wishful origin is to predict one's own invention or rather a mere basic idea of how something can be done. It rarely happens that such ideas have value, or ever are followed with important use.

The last conspicuous source of error in prediction is sheer ignorance of the latest advances in the sciences and arts involved. This has been avoided in the present volume, so far as time has allowed, by obtaining the collaboration of able scientists, and by consulting technical literature on the various points as well as the better recent predictive writings, of which a bibliography is appended.28

28 In addition to the earlier writers cited in our first section (Note 1 ff.), the following recent writings containing numerous predictions of invention seem most worthy of citation: