All observers except Clewe kept well back from the edge of the frightful hole of light down which they peered; and once, when the weight of the telescope which she held had caused Margaret to make an involuntary step forward, she gave a fearful scream, for she was sure she was going to fall into the bowels of the earth.

Clewe, who stood always near by, with his hand upon the lever which controlled the ray, instantly shut off the light; and although Margaret was thus convinced that she stood upon commonplace ground, she came from within the screen, and did not for some time recover from the nervous shock occasioned by this accident of the imagination.
Clewe himself took great pleasure in making experiments connected with the relation of the observer to the action of the Artesian ray.

For instance, he found that when standing and gazing down into the great photic perforation below him, he could see into it quite as well when he shut his eyes as when they were open; the light passing through his head made his eyelids invisible.

He stood in the very centre of the circle of light and looked down through himself.
That this application of light which he had discovered would be of the greatest possible service in surgery, Roland Clewe well knew.

By totally eliminating from view any portion of the human body so as to expose a section of said body which it was desirable to examine, the interior structure of a patient could be studied as easily as the exterior, and a surgeon would be able to dissect a living being as easily as if the subject were a corpse.