Zöllner describes how in December 1877 he put some coins in a small cardboard box and had closed it by glueing a strip of paper round the sides. He had done this in the expressed hope that Slade might be able to remove them and thus give a proof of the reality of the fourth dimension which was Zöllner's pet hobby. In May 1878 Slade came again to Leipsic and performed the feat, at any rate to the satisfaction of Zöllner.
The box was put on a table together with some slates and other objects and Slade and Zöllner and his colleagues sat round. Zöllner satisfied himself by shaking the box that the coin was still inside and in answer to Slade's enquiries explained the purpose of the experiment and its importance if successful. There was a little preliminary slate writing and then Slade began staring into a corner of the room and saying "I see funf and eighteen hundred seventy six." Then a hard object was heard to fall on the slate which Slade had held under the table all the time and on withdrawing the slate it was found to be a five mark piece of date 1876. Zöllner then snatched up the cardboard box and shook it only to find that it was empty.
This is a very highly condensed description of the proceedings but I do not think I have been guilty either of "suggestio falsi" or of "suppressio veri".
Interested readers can refer to the original.
Now, if Zöllner had been writing no more than a casual account of a well-known experiment, inserted for the sake of completeness or for similar reasons, it would be well enough.
But to offer his account, in the face of a very natural scientific incredulity, as a conclusive demonstration of a highly controversial point, was an insult to one's intelligence.
There are numerous criticisms that might be made, but I shall confine myself to pointing out only the more conspicuous of them.
In this experiment there are two main methods by which the result might have been obtained by fraudulent means.
There seems no doubt that the coin was really in the box at the beginning of the sitting. We may equally accept the statement that the box shaken at the end of the experiment did not contain a coin.