SCIENCE AND ACCURACY.
SCIENCE has been defined as certainty grounded on demonstration. In the controversy which splits the ancient Universities into two hostile camps the assumption in the scientific camp is, roughly, that science, as it is understood and represented there, produces an accurate mind, while the humanities may indeed foster a certain elegance in learning, but do not distinctively produce the essential of modern progress, accuracy. We notice in the issue of Nature published last week a summary of a paper entitled " Grandeur et Decadence des Rayons-N Histoire d'une Croyance," which was contributed to the Annie Psychologique by M. Henri Pieron. And this paper sets out an astonishing instance of an uncertainty (passing for a certainty) being grounded on demonstration. It would not be right for a moment to take the remarkable statements of M. Pi6ron as being applicable to the scientific type of mind, nor should one draw violent conclusions from them for the purposes of controversy. At the same time, the episode he describes does indicate the possibility of considerable delusions existing within the sphere of what appears at the time to be scientific demonstration, and we would do no more than call attention to it. In this sense it is a contribution to the discussion of methods of training the mind. What M. Pieron writes has long been forestalled by British and German criticism of certain French discoveries. The importance of his paper is that it is a French admission of the truth of those criticisms.
The episode of which M. Pieron writes is analysed with much knowledge in the Manchester Guardian of Monday, and upon that article we rely chiefly for our information. The famous N-rays were discovered in 1903 by Professor Blondlot, of Nancy, they were described by him to the French Academy of Sciences, and be was awarded a gold medal for his discovery. Between 1903 and 1906 no less than a hundred and seventy-six original papers were published on these mysterious rays. The phenomena which M. Blondlot himself professed to have observed were confirmed by the well-known physicists, MM. Char- pentier and Becquerel. What were these rays ? It was said that they were given off by almost all substances when in a state of strain. Thus, they were emitted by a tempered steel bar, a Nernst lamp, and even by human nerve and muscle. The more or less logical suggestion followed that if a certain radiation was given off by our bodies, according to their degree of activity, it might be possible to photograph our thoughts,—thoughts being only brain-rays. The French experimenters stated that the N-rays could be reduced, or removed, by anaesthetics.. A tempered steel bar, in fact, could be chloroformed into quiescence. One writer invited us " to revise some of our notions on the difference between the inorganic and the organic." In fine, the N-rays were even more wonderful than the Röntgen rays, and those of radium and its kindred elements. Unhappily, the N-rays did not, like the X-rays, affect photographic plates, nor even the spectroscope which is generally used in recording radio-active transformations. They were baffling and elusive, but the experimenters relied largely upon one physical effect of them, which was their power to intensify the brightness of a light. It was said that if an N-ray was directed on a spark a marked increase of luminosity was perceptible. Again, a common experiment was to hold a bar of tempered steel near a. clock in a dark room, and it was supposed to be possible then to read the time As the study of the N-rays spread M. Blondlot's con- clusions were confirmed, and even extended, outside France. But many men of science utterly failed from the first to observe any of these phenomena. In England and Germany, in particular, investigators began openly to dispute the existence of the N-rays. Professor R. W. Wood, for example, did so in a letter to Nature. The dispute became rather bitter, and to some extent it degenerated into a contest between the Latin and Teutonic minds. Many French men of science im- puted prejudice and animosity to their foreign critics ; and more lenient Frenchmen suggested that the rays were distinguishable only by the more sensitive brains of the Latin races. Britons, it seemed, were dulled by their fogs, and Germans were fogged by their beer. No other scientific controversy compares with this one. The matter in dispute threatened to place itself beyond the bounds of demonstration. There could be no such controversy about Röntgen rays or radium rays, which exercise their influence as visibly in London and Berlin as iu Paris and Nancy. The coolest French physicists gradually began to suspect that if no results could really be obtained in England and Germany, the explanation of the French experiments must be subjective rather than objective, psychological rather than physical. A simple plan for settling the question was proposed by the Revue Scientifique. Several small boxes, of exactly similar appearance, some containing pieces of lead, and others containing bars of tempered steel, were to be sealed up, and M. Blondlot or his assistants were to be asked to decide which of the boxes contained the active material. M. Blondlot refused this test, saying that " the phenomena. were far too delicate for such a trial " ; and he left " every one to form his own opinion on the N-rays either from his own experiments or from his confidence in those of others." When the dispute was thus transferred from the region of fact to that of opinion, the publication of details of experi- ments practically ceased. It is held now by all competent authorities that the N-rays had no real existence, and that the widespread belief in them was due, in M. Pieron's, words, " to illusion caused by a species of auto-suggestion based on preconceived ideas."
If it would be extremely unfair to jump to the con- clusion that proneness to delusion is at all characteristic of minds devoted to subtle physical experiments, it is none the less useful to remember that science, like old-fashioned learning and the arts and religious feeling, is capable of bringing a man into an ecstatic frame of mind which yields distortion and extravagance. The more positive statements about the N-rays came from a small band of investigators, who no doubt almost hypnotised themselves into their convictions by the unceasing reiteration of theses which they desired to believe. The work of men of science in laboratories may be extraordinarily exacting, and may impose a most damaging strain on their faculties. The fact that they are often remote from the practical world only helps to drive their judgment more out of relation to ordinary standards. One is not surprised that some of them hover to-day on the borders of the occult. And delusion, we would even go so far as to say, is peculiarly easy in the case of men who are accustomed to find that precautions of a mathematical and formal kind are sufficient to protect them against error. A charlatan may circumvent such ramparts. In the case of the N-rays, however, there is no doubt that the delusion was perfectly honest. Most of us know, in our own experience, how easy such auto-sugges- tions may be. We have heard it related that when the telephone was invented a lecturer who was giving a public exhibition of the apparatus clearly and repeatedly heard the notes of the trumpet which he had arranged should be played at the other end of the wire. Yet none of his audience could hear them ; and no wonder, for the lecturer discovered afterwards that the performer on the trumpet had made a mistake in the day, and was not there at all. It may be said that the myth of the N-rays was exploded in the end, that it was exploded by men of science themselves, and that one cannot reasonably ask for more. This, no doubt, is true, and the fact is reassuring. But the point, which is a minor one, is rather that accurate methods may themselves require accurate verification. The guardians of physical truth may themselves need guarding. They have not a monopoly of accuracy.
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