© Tom Lethbridge 1969 
No one with the slightest curiosity in his make-up can resist experimenting with the information freely presented to him by the writers of letters. We saw that something of the personality of an Iron Age slinger remained for two thousand years in the field of the stone he slung.
It is just the same with a letter. Something of your personality remains in it, which is beyond what you said in the words you wrote on the paper. This is in accord with some modern theories of how memory functions, and although these have not yet been presented to the general seeker-after-truth, it seems evident to me that they must be nearer the correct answer than anything that has gone before. The holographic function of the mind is the coming idea.
What do you want to know about the people who have written to you? As this is, we hope, a scientific investigation, you want to catalogue them under various headings. We had over a hundred cards at Christmas and this seemed quite a big enough sample to learn something, although I might not believe what the pendulum said. Again and again I have to stress that I approach all this with complete disbelief. I am a most down-to-earth person and have had a scientific upbringing and training. I just do not accept anything the pendulum says without a struggle in my own mind.
You must understand that we have worked out a table of rates, which comprises many things, and it seemed reasonable to try some of these in relation to others. I chose 9Ĺ inches, which appears to represent the psychic potential of a person, and which I call the psi rate; 16 inches which apparently indicates the sex potential; 19Ĺ, which stands for blood and may show something about its character; and 30 inches, which stands for age. It soon became clear that the age rate had no effect on the sex or psi potential. Nevertheless this is the one I am going to discuss now.
In all, we tested 120 specimens, and whenever we knew a personís age the pendulum was right within two revolutions. The method was to start the pendulum gently swinging over the specimen of handwriting when it had been set at the 30 inches rate for age. Then, quite arbitrarily, but apparently correctly, we counted one year for each turn the pendulum made.
It is not easy to be quite sure when the revolutions start and when they stop and this is why one is liable to an error of a year at either end. Critics of this method must try it out for themselves before they are in a position to form any judgement of its accuracy. It sounds complete nonsense and yet it appears to work. The proof of the pudding is not in what it looks like, but in how it tastes. 
Not long ago, my publisher, Colin Franklin, set me off on a problem, which seems to be in the correct line. Put shortly, he wanted to know whether the reproductions of pictures still retained the sex rate of the painters of the originals. Now this is surely an important question and goes quite a long way to further the investigation. To enlarge it somewhat, one might ask whether a book carries with it part of the original field of force of the author.
If it should do so then a book might be compared with the laying on of hands in consecrating a priest. People have told me that there is a gap of 200 years in this ceremony and that power is no longer handed on in direct succession. I do not know about this; but the possibility that part of the authorís psyche-field might go with each copy of a book which he had written struck me as being very interesting. I did not believe it for a moment.
Now unless you are prepared to wander round public art galleries with a folio of reproductions and a pendulum, it is not very easy to find the answer to Colin Franklinís question. I thought about it for some time before I hit on a possible way of testing it. I draw the illustrations, of doubtful value, which accompany my books. I asked him to send me back the original drawings from one of them. I supposed that they were filed somewhere and not destroyed when the blocks were made.
My idea was to test first an original drawing for the sex and thought rates and then to test the reproduction made from that drawing in a completely new and unopened copy of the book itself. Of course many people handled the drawings in the course of making the blocks from them and some slight handling may have occurred in the printing and binding of the book. That we had to risk, but the risk did not appear to be great.
In due course a folder of drawings arrived and I took them to the slate floor in the hall, where there should not be much interruption from anything but the slate. In a state of considerable interest, I put the first drawing on the floor and tested it for the rate for male sex of 24 inches and then for thought at 27 inches. It responded strongly to both.
Then I opened the new copy of the book at the figure made from the drawing and tested that. There was no reaction of any sort to either rate. The figure appeared to be dead. My wife and I went solemnly through the drawings and the prints made from them. All the drawings responded to the sex and thought rates. Nothing at all happened with the prints. There was no reaction for either rate from the book itself. There was not the slightest indication that any fragment of the authorís personality passed to the book, except that the printed word might mean something to the person who read it. There was no direct contact at all.
The book was not a link in any parapsychological sense between the author and the reader. There was nothing passing between an artist who painted a picture and the reproduction of that picture. The quality of the reproduction, however good it might be, is something entirely mechanical and lacking in the life force which had been impressed by the artist on the original. We have already seen the same kind of thing suggested by thinking about photographs. The photograph appears dead, so is the reproduction by mechanical means of an original picture. A hand-made copy would of course react to the sex rate of the person who made the copy.
The experiment was rather a relief to me. I had not been able to see how anything could really pass from original to reproduction. Whereas everything we had investigated before followed a logical course, however strange that course might appear to be, this transference of something to a reproduction seemed completely illogical. Yes, I was relieved. Crazy though we might seem to be; yet we were not so daft as all that. We had managed to put a brake on.
 Source: Chapter 9 in The Monkey's Tail; Routledge & Kegan Paul, 1969, SBN 7100 6598 1.
 Source from here: Chapter 6 in ESP: Beyond Time and Distance; Routledge & Kegan Paul, 1965.