Greatly astonished, he lifted it out of the light ray and carried it to the darkest part of the shop. It remained bright for some four or five minutes, when it slowly faded and went out. He placed it in the thin streak of daylight, and its luminousness was almost immediately restored.
So far, at least, Mr. Wace was able to verify the remarkable story of Mr. Cave. He has himself repeatedly held this crystal in a ray of light (which had to be of a less diameter than one millimetre). And in a perfect darkness, such as could be produced by velvet wrapping, the crystal did undoubtedly appear very faintly phosphorescent. It would seem, however, that the luminousness was of some exceptional sort, and not equally visible to all eyes; for Mr. Harbinger—whose name will be familiar to the scientific reader in connection with the Pasteur Institute—was quite unable to see any light whatever. And Mr. Wace's own capacity for its appreciation was out of comparison inferior to that of Mr. Cave's. Even with Mr. Cave the power varied very considerably: his vision was most vivid during states of extreme weakness and fatigue.
Now, from the outset this light in the crystal exercised a curious fascination upon Mr. Cave.
