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THE METAL-BENDERS” by JOHN B. HASTED

The detection of metal-bending action

It occurred to me at a very early stage, during the Society for Psychical Research 1975 experiments carried out with Graham and Valerie P. at City University, London, that very small elastic deformations might be of common occurrence in metal-bending sessions; they would be undetectable by eye, and would result in no permanent deformation; but they could possibly be detected by instruments. Therefore I thought it would be useful to provide the metal specimens with a sensitive device capable of detecting small strains (elongations or deformations), such as are produced by, or at any rate associated with, stress (force or moment).

I found the resistive strain gauge(22) to be by far the most suitable instrument for this purpose. One modern type of gauge consists of a thin film, typically of the alloy constantan, in the form of a folded filament, deposited on a small thin plastic sheet (see Figure 4.l). The gauge is either stuck onto a metal surface or onto the inner surface of a cavity machined in the metal; the plastic is sufficiently thin (<= 0.05 mm) for it not to reinforce the metal but to bend or extend with it.

The electrical resistance of the constantan filament varies proportionally to its length (normal length plus strain), so that a suitable battery operated electrical bridge circuit and amplifier (Figure 4.1, as first built by my technician Nick Nicola) produces a time-varying voltage proportional to time-varying strain. This ‘analogue signal’ can be recorded on magnetic tape, or better still on a chart-recorder; thereby we obtain a measure of how long the strain lasts and how large it is.

Suitable design enables very small strains to be measured, so that weak ‘powers’ of a paranormal metal-bender can be detected even though the specimen is far below the condition of permanent deformation. Calibration of the instrument is summarized in Table 4.1.

Figure 4.1 Bridge and amplifier circuit for use with resistive strain gauge and chart-recorder; strain gauge (Micro-Measurements type EAO9 125 BT 120) is shown enlarged.
 

I built the device with electrical screening of the wires, sufficient to ensure that artefacts would not occur from electrostatic or electromagnetic causes.

In the initial version a gauge was stuck onto a brass strip by Mr Chapman at the City University, and the boy whom we were studying (Graham P.) was allowed to stroke the strip with the ball of his forefinger.

To our surprise some sharp little pulses appeared on the chart-record. When I myself stroked the sensor in a similar manner no pulses appeared. But at this stage Chapman and I were not convinced that we had recorded the phenomenon for the first time. We were both sceptical and thought that electrostatic artefacts must have been responsible. The signals were small, and I thought it possible that they could have arisen from the finger’s jumping from point to point, in the manner of chalk producing an involuntary dotted line on a blackboard. In retrospect it now seems possible that these were genuine paranormal signals, but I decided at the time to make two drastic changes:

1 The strain gauge was to be enclosed within a cavity in the metal, and electrically screened as far as possible.
2 The child must not be allowed to touch the metal with his fingers.

With the new policy l started exposing strain gauges in latchkeys to the children l visited,

• Belinda H.,
• Julie Knowles,
• Andrew G.,
• Willie G.,
• Richard B.,
• Nicholas Williams,
• Alison Lloyd,
• Mark Henry,
• David and Steven Nemeth,
• Clifford White,
• Gill Costin and
• Neil Howarth.

All of them managed to produce signals without touch, and l have since successfully exposed the sensors to other subjects in other countries.

Children enjoyed playing with the latchkeys in which the first strain gauges were mounted (Plate 4.1). When the key is deformed elastically between the fingers and thumb, a deflection can be seen on the chart-record, with the paper moving typically at a speed of 1 inch every 5 seconds.

A latchkey is difficult to deform permanently by finger pressure alone, so the chart-recorder trace returns to approximately its original level. The device is such a pleasant toy that we might recommend its production commercially. Of course we must avoid the use of ferromagnetic metals, since spontaneous relaxation of domains might cause signals due to the Barkhausen effect.