Observations placeholder

THE METAL-BENDERS” by JOHN B. HASTED

For a single-handed bend the situation is more complicated. When a specimen is held and stroked between fingers and thumb, parts of the specimen are concealed from view by parts of the hand. This screening is minimized when the observers view from different angles and different heights (e.g., with a mirror-surface table). A three-point load can most easily be applied to a specimen, using one hand, by

(a) the ball of the thumb,
(b) the first or second joint of the forefinger, and
(c) the base of the palm.

The bend will then be centred on the point of application of the forefinger.

If the specimen is only about 5 cm long (e.g., a latchkey), then it is not possible to apply a three-point load in this way; instead the thumb and two fingers would be used; in this operation much more of the specimen is exposed to view.

I have used latchkey specimens for this reason.

On occasions I have noticed that paranormal bending takes place beyond the end of the thumb and fingers, which would be impossible under normal bending from a physical three-point load.

When the bend is gradual, it is difficult to be certain that there is no physical three-point load throughout the time of bend. But on one occasion a single crystal of zinc was stroked between the fingers and thumb by Graham P., under good conditions of observation; I observed an instantaneous cleavage beyond the end of the fingers and thumb. The end of the crystal dropped to the table, leaving the remainder of the crystal exposed, projecting beyond the fingers and thumb.

A sudden event of this sort enables the observer to be certain that the position of cleavage is not between the two outer loading points and, therefore, that physical force of the fingers and thumb could not have caused the cleavage.