In the first edition of this Essay I did not introduce any of my own observations, because I had not then witnessed any such facts in a private house, and without the intervention of paid mediums, as would be likely to satisfy my readers. Having now had the opportunity of investigating the subject under more favourable conditions, I will give some account of my early personal experience, which many of my friends are so polite and illogical as to say will have more weight with them than all the other witnesses whose evidence I have adduced. I will begin with what first led me to inquiries outside the pale of what is generally recognised as science.
My earliest experiences on any of the matters treated of in this little work was in 1844, at which time I was teaching in a school in one of the Midland Counties. Mr. Spencer Hall was then lecturing on Mesmerism, and visited our town, and I and many of my pupils attended his lectures. We were all greatly interested. Some of the elder boys tried to mesmerise the younger ones, and succeeded; and I myself found several who, under my influence, exhibited many of the most curious phenomena we had witnessed at the lectures. I was intensely interested in the subject, and pursued it with ardour, carrying out a number of experiments to guard against deception and to test the nature of the influence. Many of the details of these experiments are now stamped as vividly on my memory as if they were events of yesterday; and I will briefly give the substance of a few of the more remarkable.
1. Phenomena during the Mesmeric Trance.—I produced the trance state in two or three boys, of twelve to sixteen years of age, with great ease, and could always be sure that it was genuine, first, by the turning of the eyeball in the orbit, so that the pupil was not visible when the eyelid was raised; secondly, by the characteristic change of countenance; and, thirdly, by the readiness with which I could produce catalepsy and loss of sensation in any part of the body. The most remarkable observations during this state were on phreno-mesmerism and sympathetic sensation. By placing my finger on the part of the head corresponding to any given phrenological organ, the corresponding faculty was manifested with wonderful and amusing perfection. For a long time I thought that the effects produced on the patient were caused by my wishing the particular manifestation; but I found by accident that when, by ignorance of the position of the organs, I placed my finger on a wrong part, the manifestation which followed was not that which I expected, but that which was due to the position touched. I was particularly interested in phenomena of this kind, and by experiments made alone and silently, completely satisfied myself that the effects were not due to suggestion or to the influence of my own mind. I had to buy a little phrenological bust for my own use, and none of the boys had the least knowledge of or taste for phrenology; yet, from the very first, almost all the organs touched, in however varied order and in perfect silence, were followed by manifestations too striking to be mistaken, and presenting more wonderful representations of varied phases of human feeling than the greatest actors are able to exhibit.
The sympathy of sensation between my patient and myself was to me the most mysterious phenomenon I had ever witnessed. I found that when I laid hold of his hand
he felt, tasted, or smelt exactly the same as I did. I had already produced all the phenomena of suggestion, and could make him tipsy with a glass of water by calling it brandy, and cause him strip off all his clothes by telling him he was on fire; but this was quite another thing. I formed a chain of several persons, at one end of which was the patient, at the other myself. And when, in perfect silence, I was pinched or pricked, he would immediately put his hand to the corresponding part of his own body, and complain of being pinched or pricked too. If I put a lump of sugar or salt in my mouth, he immediately went through the action of sucking, and soon showed by gestures and words of the most expressive nature what it was I was tasting. I have never to this day been satisfied with any of the explanations given of this fact by our physiologists for they resolve themselves into this, that the boy neither felt nor tasted anything, but acquired a knowledge of what I was feeling and tasting by a preternatural acuteness of hearing. That he had any such preternatural acuteness was, however, contrary to all my experience, and the experiment was tried so as expressly to prevent his gaining any knowledge of what I felt or touched by means of the ordinary senses.
2. Phenomena during the Waking State.—After I had induced the state of coma several times, some of the boys became very susceptible during their ordinary waking condition. I could induce catalepsy of any of the limbs with great ease; and some curious little facts showed that it was real, not imaginary, rigidity that was produced. Once a boy was in my room in a state of complete rigidity when the dinner-bell rang. I hastily made passes to relax the body and limbs, and we went down together. When his plate was before him, however, he found that he could not bend one of his arms, and, not liking to say anything,
sat some time trying to catch my eye. I then had to go to him, and by two or three passes rendered him able to eat his dinner. This is a curious and important fact, because the boy went down thinking he was all right. The rigidity was therefore in no way caused by his "expectation," since it existed in opposition to it. In this boy and another one I could readily produce the temporary loss of any of the senses, as hearing or smelling; and could even so completely take away the memory that the patient could not tell his own name, greatly to his disgust and confusion, and this by nothing more than a simple pass across the face, and saying in an ordinary tone of voice, "Now, you can't tell me your name." And after he had remained utterly puzzled for some minutes, if I made a reverse pass, and said, "Now, you know your name again," his whole countenance would change—a look of relief coming over it as the familiar words recurred suddenly to his memory.
Such facts as these were at that period generally imputed to acting and trick on the part of the patients. Now, most of our physiologists admit them to be genuine mental phenomena, and attempt to explain them by "abstraction" and "suggestion"—denying any specific action of the operator on the patient. This appears to me to be really no explanation at all; and I am confirmed in this view when I find that those who put it forward deny the reality of all facts that do not square with it. All such phenomena as phreno-mesmerism, and sympathetic sensation, and true clairvoyance, which have been elaborately examined and tested by a score of good observers, are nevertheless denied a place in the repertory of established scientific facts by those who profess to study all the phenomena of the organism or of the mind of man. These personal experiences having enabled me to detect the more subtle indications
of the mesmeric coma, I have since taken every opportunity of witnessing the phenomena in public and private, and am quite satisfied that, in the more remarkable manifestations, there is, or can be, very rarely any deception practised.
As Dr. Carpenter and other men of science still maintain the view that all the higher phenomena of Spiritualism which are not imposture are due to subjective impressions, analogous to those produced in his patients by the mesmeriser, I will here point out certain characteristic differences between the two classes of facts, which I first adduced in reply to Mr. E. B. Tylor in a letter in Nature (1872, p. 364).
1. The mesmerised patient never has doubts of the reality of what he sees or hears. He is like a dreamer, to whom the most incongruous circumstances suggest no idea of incongruity, and he never inquires if what he thinks he perceives harmonises with his actual surroundings. He has, moreover, lost his memory of what and where he was a few moments before; and can give no account, for instance, of how he managed to get from a lecture-room in London, to which he came as a spectator half-an-hour ago, on to an Atlantic steamer in a hurricane, or into the presence of a tiger in a tropical jungle. The assistants at the séances of Mr. Home or Mrs. Guppy are not in this state, as even our opponents will admit, and as the almost invariable suspicion of fraud with which the phenomena are at first regarded clearly demonstrates. They do not lose all memory of immediately preceding events; they criticise; they examine; they take notes; they suggest tests—none of which things the mesmerised patient ever does.
2. The mesmeriser has the power of acting on certain sensitive individuals (not on assemblies of people, as Mr. Tylor assumes), and all experience shows that those who
are thus sensitive to any one operator are but a small proportion of any body of people, and even these almost always require previous manipulation, with an almost passive submission to the operator. The number who can be acted on without such previous manipulation is very small, probably less than one per cent. But there is no such limitation to the number of persons who simultaneously witness most of the mediumistic phenomena. The visitors to Mr. Home or Mrs. Guppy all see whatever occurs of a physical nature, as the records of hundreds of sittings, and even the evidence of sceptics, demonstrate.
The two classes of phenomena, therefore, differ fundamentally; yet there is a connection between them, but in an opposite direction to that suggested. It is the mediums, not the assistants, who are "sensitives." They are almost always persons who are subject to the mesmeric influence, and they often exhibit all the characteristic phenomena of coma, trance, rigidity, and abnormal sense-power. Conversely, the most sensitive mesmeric patients are almost always mediums.
The differences now pointed out are so radical and so important that it does not say much for the logical clearness of those who persist in classing the two phenomena as identical. But the manner in which men of great eminence fail to see the bearing of facts when that bearing is against their pet theories will be further illustrated by a few examples in the appendix to this volume.
3. Experiences and Tests of Modern Spiritual Phenomena.—During twelve years of tropical wanderings between the years 1848 and 1862, occupied in the study of natural history, I heard occasionally of the strange phenomena said to be occurring in America and Europe under the general names of "table-turning" and "spirit-rapping;" and being aware, from my own knowledge of
Mesmerism, that there were mysteries connected with the human mind which modern science ignored because it could not explain, I determined to seize the first opportunity on my return home to examine into these matters. It is true, perhaps, that I ought to state that for twenty-five years I had been an utter sceptic as to the existence of any preter-human or super-human intelligences, and that I never for a moment contemplated the possibility that the marvels related by Spiritualists could be literally true. If I have now changed my opinion, it is simply by the force of evidence. It is from no dread of annihilation that I have gone into this subject; it is from no inordinate longing for eternal existence that I have come to believe in facts which render this highly probable, if they do not actually prove it. At least three times during my travels I have had to face death as imminent or probable within a few hours, and what I felt on those occasions was at most a gentle melancholy at the thought of quitting this wonderful and beautiful earth to enter on a sleep which might know no waking. In a state of ordinary health I did not feel even this. I knew that the great problem of conscious existence was one beyond man's grasp, and this fact alone gave some hope that existence might be independent of the organised body. I came to the inquiry, therefore, utterly unbiassed by hopes or fears, because I knew that my belief could not affect the reality, and with an ingrained prejudice against even such a word as "spirit," which I have hardly yet overcome.
It was in the summer of 1865 that I first witnessed any of the phenomena of what is called Spiritualism, in the house of a friend—a sceptic, a man of science, and a lawyer, with none but members of his own family present. Sitting at a good-sized round table, with our hands placed upon it, after a short time slight movements would commence
not often "turnings" or "tiltings," but a gentle intermittent movement, like steps, which after a time would bring the table quite across the room. Slight but distinct tapping sounds were also heard. The following notes made at the time were intended to describe exactly what took place: —"July 22nd, 1865.—Sat with my friend, his wife, and two daughters, at a large loo table, by daylight. In about half-an-hour some faint motions were perceived, and some faint taps heard. They gradually increased; the taps became very distinct, and the table moved considerably, obliging us all to shift our chairs. Then a curious vibratory motion of the table commenced, almost like the shivering of a living animal. I could feel it up to my elbows. These phenomena were variously repeated for two hours. On trying afterwards, we found the table could not be voluntarily moved in the same manner without a great exertion of force, and we could discover no possible way of producing the taps when our hands were upon the table."
On other occasions we tried the experiment of each person in succession leaving the table, and found that the phenomena continued the same as before, both taps and the table movement. Once I requested one after another to leave the table; the phenomena continued, but as the number of sitters diminished with decreasing vigour, and just after the last person had drawn back leaving me alone at the table, there were two dull taps or blows, as with a fist on the pillar or foot of the table, the vibration of which I could feel as well as hear. No one present but myself could have made these, and I certainly did not make them. These experiments clearly indicated that all were concerned in producing the sounds and movements, and that if there was any wilful deception the whole party were engaged in deceiving me. Another time we sat half-an-hour at the large table, but had no mani-
festations whatever. We then removed to the small table, where taps immediately commenced and the table moved. After some time we returned to the large table, and after a few minutes the taps and movements took place as at the small one.
The movement of the table was almost always in curves, as if turning on one of the claws, so as to give a progressive motion. This was frequently reversed, and sometimes regularly alternate, so that the table would travel across the room in a zigzag manner. This gives an idea of what took place with more or less regularity during more than a dozen sittings. Now there can be no doubt that the whole of the movements of the table could have been produced by any of the persons present if not counteracted by the others, but our experiments showed that this could not always be the case, and we have therefore no right to conclude that it was ever the case. The taps, on the other hand, we could not make at all. They were of about the quality that would be produced by a long finger-nail tapping underneath the leaf of the table. As all hands were on the table, and my eyes at least always open, I know they were not produced by the hands of any one present. They might possibly have been produced by the feet if properly armed with some small hard point to strike with; but if so, the experiments already related show that all must have practised the deception. And the fact that we often sat half an hour in one position without a single sound, and that the phenomena never progressed further than I have related, weighs I think very strongly against the supposition that a family of four highly intelligent and well-educated persons should occupy themselves for so many weary hours in carrying out what would be so poor and unmeaning a deception. The following remark occurs at the end of my notes made at the time: "These experi-
ments have satisfied me that there is an unknown power developed from the bodies of a number of persons placed in connection by sitting round a table with all their hands upon it."
Some time before these observations I had met a gentleman who had told me of most wonderful phenomena occurring in his own family—among them the palpable motion of solid bodies when no person was touching them or near them; and he had recommended me to go to a public medium in London (Mrs. Marshall), where I might see things equally wonderful. Accordingly, in September 1865, I began a series of visits to Mrs. Marshall, generally accompanied by a friend—a good chemist and mechanic, and of a thoroughly sceptical mind. What we witnessed may be divided into two classes of phenomena—physical and mental. Both were very numerous and varied; but I shall only select from each a few which are of a clear and definite nature.
1st. A small table, on which the hands of four persons were placed (including my own and Mrs. Marshall's), rose up vertically about a foot from the floor, and remained suspended for about twenty seconds, while my friend, who was sitting looking on, could see the lower part of the table with the feet freely suspended above the floor.
2nd. While sitting at a large table, with Miss T. on my left and Mr. R. on my right, a guitar which had been placed in Miss T.'s hand slid down on to the floor, passed over my feet, and came to Mr. R., against whose legs it raised itself up till it appeared above the table. I and Mr. R. were watching it carefully the whole time, and it behaved as if alive itself, or rather as if a small invisible child were by great exertions moving it and raising it up. These two phenomena were witnessed in bright gaslight.
3rd. A chair, on which a relation of Mr. R.'s sat, was
lifted up with her on it. Afterwards, when she returned to the table from the piano, where she had been playing, her chair moved away just as she was going to sit down; on drawing it up, it moved away again. After this had happened three times, it became apparently fixed to the floor, so that she could not raise it. Mr. E. then took hold of it, and found that it was only by a great exertion he could lift it off the floor. This sitting took place in broad daylight, on a bright day, and in a room on the first floor with two windows.
However strange and unreal these few phenomena may seem to readers who have seen nothing of the kind, I positively affirm that they are facts which really happened just as I have narrated them, and that there was no room for any possible trick or deception. In each case, before we began, we turned up the tables and chairs, and saw that they were ordinary pieces of furniture, and that there was no connection between them and the floor, and we placed them where we pleased before we sat down. Several of the phenomena occurred entirely under our own hands, and quite disconnected from the "medium." They were as much realities as the motion of nails towards a magnet, and, it may be added, not in themselves more improbable or more incomprehensible.
The mental phenomena which most frequently occur are the spelling out of the names of relations of persons present, their ages, or any other particulars about them. They are especially uncertain in their manifestation, though when they do succeed they are very conclusive to the persons who witness them. The general opinion of sceptics as to these phenomena is, that they depend simply on the acuteness and talent of the medium in hitting on the letters which form the name, by the manner in which persons dwell upon or hurry over them the ordinary
mode of receiving these communications being for the person interested to go over a printed alphabet, letter by letter—loud taps indicating the letters which form the required names. I shall select a few of our experiences, which will show how far this explanation is likely to be a true one.
When I first received a communication myself, I was particularly careful to avoid giving any indication, by going with steady regularity over the letters; yet there was spelt out correctly, first, the place where my brother died, Para; then his Christian name, Herbert; and lastly, at my request, the name of the mutual friend who last saw him, Henry Walter Bates. On this occasion our party of six visited Mrs. Marshall for the first time, and my name, as well as those of the rest of the party, except one, were unknown to her. That one was my married sister, whose name was no clue to mine.
On the same occasion a young lady, a connection of Mr. K.'s, was told that a communication was to be made to her. She took the alphabet, and instead of pointing to the letters one by one, she moved the pencil smoothly over the lines with the greatest steadiness. I watched her, and wrote down the letters which the taps indicated. The name produced was an extraordinary one, the letters making Thomas Doe Thacker. I thought there must be an error in the latter part; but the names were really Thomas Doe Thacker, the lady's father, every letter being correct. A number of other names, places, and dates were spelt out on this occasion with equal accuracy; but I give only these two, because in these I am sure that no clue was given by which the names could have been guessed by the most preternaturally acute intellect.
On another occasion, I accompanied my sister and a lady (who had never been there before) to Mrs. Marshall's,
and we had a very curious illustration of the absurdity of imputing the spelling of names to the receiver's hesitation and the medium's acuteness. She wished the name of a particular deceased relation to be spelled out to her, and pointed to the letters of the alphabet in the usual way, while I wrote down those indicated. The first three letters were y r n. "Oh!" said she, "that's nonsense; we had better begin again." Just then an e came, and thinking I saw what it was, I said—"Please go on, I understand it." The whole was then spelt out thus—yrnehkcocffej. The lady even then did not see it, till I separated it thus—yrneh kcocffej, or Henry Jeffcock, the name of the relation she had wanted accurately spelt backwards.
Another phenomenon, necessitating the exertion both of force and intellect, is the following: —The table having been previously examined, a sheet of note-paper was marked privately by me, and placed with a lead pencil under the centre foot of the table, all present having their hands upon the table. After a few minutes taps were heard, and on taking up the paper I found written on it in a free hand—William. On another occasion, a friend from the country—a total stranger to the medium, and whose name was never mentioned—accompanied me; and, after receiving what purported to be a communication from his son, a paper was put under the table, and in a few minutes there was found written on it Charley T. Dodd, the correct name. In these cases it is certain there was no machinery under the table; and it simply remains to ask, if it were possible for Mrs. Marshall to slip off her boots, seize the pencil and paper with her toes, and write on it a name she had to guess at, and again put on her boots without removing her hands from the table, or giving any indication whatever of her exertions?
I now for some months left off going to Mrs. Marshall's, and endeavoured to produce the phenomena at home. My friend Mr. K. soon found he had the power to produce slight movements of the table, but they were never of such a nature as to satisfy an observer that they were not produced consciously or unconsciously by our own muscles. The style and character of the communications obtained through these movements were, however, such as to satisfy me that our own minds had no part in producing them.
We tried among all our friends to find one who had power to produce distinct taps, a class of phenomena that appeared to us much more satisfactory, because we could not produce them ourselves, either consciously or unconsciously, under the same conditions. It was in November 1866 that my sister discovered that a lady living with her had the power of inducing loud and distinct taps and other curious phenomena, and I now began a series of observations in my own house, the most important of which I shall briefly narrate.
When we sat at a large loo table without a cloth, with all our hands upon it, the taps would generally commence in a few minutes. They sounded as if made on the under side of the leaf of the table, in various parts of it. They changed in tone and loudness, from a sound like that produced by tapping with a needle or a long finger-nail, to others like blows with a fist or slaps with the fingers of a hand. Sounds were produced also like scraping with a finger-nail, or like the rubbing of a damp finger pressed very hard on the table. The rapidity with which these sounds are produced and are changed is very remarkable. They will imitate, more or less exactly, sounds which we make with our fingers above the table; they will keep good time to a tune whistled by one of the party; they will sometimes, at request, play a very fair tune them-
selves, or will follow accurately a hand tapping a tune upon the table. When these sounds are heard repeatedly in one's own well-lighted room, upon one's own table, and with every hand in the room visible, the ordinary explanations given of them seem utterly untenable. Of course the first impression on hearing a few taps only is, that some one is making them with the feet. To set this doubt at rest, we have on several occasions all knelt down round the table, and yet the taps have continued, and have not only been heard as if on the leaf of the table, but have been felt vibrating through it. Another view is, that the sounds are produced by the slipping of tendons or the cracking of joints in some parts of the medium's body; and this explanation is, I believe, the one most commonly accepted by scientific men. But surely, if this be so, some one case can be brought forward in which a person's bones or tendons can make sounds like tapping, rapping, thumping, slapping, scratching, and rubbing, and can repeat some of these so rapidly as to follow every tap of an observer's fingers, or to keep time to music; and further, that all these sounds shall appear to every one present not to come from the individual's body, but from the table at which he is sitting, and "which shall often vibrate when the sounds are heard. Until such a case is produced I must be excused for marvelling at the credulity of those who accept so absurd and inadequate an explanation.
A still more remarkable phenomenon, and one which I have observed with the greatest care and the most profound interest, is the exhibition of considerable force under conditions which preclude the muscular action of any of the party. We stood round a small work-table, whose leaf was about twenty inches across, placing our hands all close together near the centre. After a short time
the table would rock about from side to side, and then, appearing to steady itself, would rise vertically from six inches to a foot, and remain suspended often fifteen or twenty seconds. During this time any one or two of the party could strike it or press on it, as it resisted a very considerable force. Of course, the first impression is that some one's foot is lifting up the table. To answer this objection, I prepared the table before our second trial without telling any one, by stretching some thin tissue paper between the feet an inch or two from the bottom of the pillar, in such a manner that any attempt to insert the foot must crush and tear the paper. The table rose up as before, resisted pressure downwards, as if it were resting on the back of some animal, sunk to the floor, and in a short time rose again, and then dropped suddenly down. I now with some anxiety turned up the table, and, to the surprise of all present, showed them the delicate tissue stretched across altogether uninjured! Finding that this kind of test was troublesome, as the paper or threads had to be renewed every time, and were liable to be broken accidentally before the experiment began, I constructed a cylinder of hoops and laths, covered with canvas. The table was placed within this as in a well, and, as it was about eighteen inches high, it effectually kept feet and ladies' dresses from the table. This apparatus in no way checked the table's upward motion, and as the hands of the medium were always close under the eyes of all present, and simply resting on the top of the table, it would appear that there was some new and unknown power here at work. These experiments have been many times repeated by me, and I am satisfied of the correctness of my statement of the facts.
On two or three occasions only, when the conditions appear to have been unusually favourable, I have witnessed
a still more marvellous phenomenon. While sitting at the large table in our usual manner, I placed the small table about four feet from it, on the side next the medium and my sister. After some time, while we were talking, we heard a slight sound from the table, and looking towards it, found that it moved slightly at short intervals, and after a little time it moved suddenly up to the table by the side of the medium, as if it had gradually got within the sphere of a strong attractive force. Afterwards, at our request, it was thrown down on the floor without any person touching it, and it then moved about in a strange life-like manner, as if seeking some means of getting up again, turning its claws first on one side and then on the other. On another occasion a very large leather arm-chair which stood at least four or five feet from the medium, suddenly wheeled up to her after a few slight preliminary movements. It is, of course, easy to say that what I relate is impossible. I maintain that it is accurately true; and that no man, whatever be his attainments, has such an exhaustive knowledge of the powers of nature as to justify him in using the word impossible with regard to facts which I and many others have repeatedly witnessed.
On Wednesday evening, February 27, 1867, some very remarkable phenomena occurred. The parties present were my sister and Miss Nichol (now Mrs. Volckman), her father, Mr. H. T. Humphreys, and two young friends of mine, Mr. and Miss M. My wife and her sister also sat in the room at some distance from the table looking on. There was no fire, and we lowered the gas so as to give a subdued light, which enabled everything to be seen. The moment we were all in our places, taps were heard indicating that the conditions were favourable. We now sent for a single wine-glass, which was placed on the floor between Miss Nichol and her father, and we requested it might be
truck. After a short time it was gently tapped, producing a clear ringing sound. This soon changed to a sound as if two glasses were gently struck together; and now we were all astonished by hearing in succession almost every possible sound that could be produced by two glasses one inside the other, even to the clang of one dropped into another. They were in every respect identical with such sounds as we could produce with two glasses, and with two only, manipulated in a variety of ways, and yet I was quite sure that only one wine-glass was in the room, and every person's hands were distinctly visible on the table.
We now took up the glass again and put it on the table, where it was held by both Miss N. and Mr. Humphreys, so as to prevent any vibration it might produce. After a short interval of silence an exquisitely delicate sound as of tapping a glass was heard, which increased to clear silvery notes like the tinkling of a glass bell. These continued in varying degrees for some minutes, and then became fainter and gradually died away. We afterwards placed a rude bamboo harp from the Malay Archipelago under the table, and, after several alterations of position, the strings were twanged as clearly and loudly as any of us could do it with our fingers. Having had such success with the glass, we asked if the harp could also be imitated, and having received permission to try, placed it also on the table. After a little time faint vibrating taps were heard, and these soon changed into very faint twangs which formed a distinct imitation of the harp strings, although by no means so successfully as in the case of the wine-glass.
We were informed by taps in the ordinary way that it was through the peculiar influence of Mr. Nichol that this extraordinary production of imitative musical sounds without any material object was effected. I may add that the imitation of the sound produced by two glasses was so
perfect that some of the party turned up the table immediately after we left it, under the impression that the unseen power had brought in a second glass, but none could be found.
It has been objected that we too often use the expression that the phenomena we witness "could not possibly have been produced by any of the persons present." I maintain that in this instance they could not, and I shall continue in that conviction until they are produced under similar conditions and the modus operandi explained.
I have since witnessed a great variety of phenomena, both in this country and in America, some of which are alluded to in other parts of this volume; but I attach most importance to those which I have carefully and repeatedly tested, and which give me a solid basis of fact by which to judge of what others relate or of what I have myself seen under less favourable conditions.