"Because the diamond is a gem possessing a greater refractive power than any other precious stone, and reflects every atom of light which falls upon it at an angle of incidence greater than twenty-four and a half degrees, even before being cut. I remember that Benvenuto Cellini, in his History of Jewelry, mentions a magnificently colored carbuncle, which was found in a vineyard near Rome simply by its shining in the night. Stand steadily where you are, Dick, and don't lose sight of it, while I advance up the ravine."
He did so thrice, and each time found that on proceeding about twenty yards, it faded away altogether.
"It is very probably a mere rock crystal," said I.
"No rock crystal ever shone with a brilliance like that!" replied Hislop, vehemently; "but whether it is a diamond of the purest water or a will-o'-the-wisp—a spunkie, as we call it in Scotland—I'll give it a touch with a short Enfield, point-blank."
Hislop's rifle was already capped and loaded, but with his knife he shaped an oblong bullet of the hard white chalk which he had procured at Orotava, and carefully rammed it down the barrel.
Having some matches about him, he touched the knob of the foresight and the notch of the back-sight with phosphorus, and thus bringing the two lights in a line with the diamond, he took a long and steady aim from his left knee, and fired!
The dark valley and the steep mountains rang with a thousand reverberations, as they seemed to toss the sharp report from echoing rock to rock, until it died away in mid-air; but still the diamond shone as brightly as ever, and our horses plunged so wildly that they nearly broke away from us.
"If my aim is true, and the chalk bullet has struck the rock, it will indicate the bearings of the diamond, and we may unship it somehow in the morning," said the practical Scotchman, as he quietly reloaded.
"Morning? Must we wait here till then?"
"Well, Dick, it is worth waiting for; and after all we have gone through since that day when we picked you up adrift in the chops of the Channel, we may sleep here pleasantly enough in one of the thickets."