We had soon touched land in the same place as before and set to provision the block house. All three made the first journey, heavily laden, and tossed our stores over the palisade. Then, leaving Joyce to guard them—one man, to be sure, but with half a dozen muskets—Hunter and I returned to the jolly–boat and loaded ourselves once more. So we proceeded without pausing to take breath, till the whole cargo was bestowed, when the two servants took up their position in the block house, and I, with all my power, sculled back to the HISPANIOLA.

That we should have risked a second boat load seems more daring than it really was. They had the advantage of numbers, of course, but we had the advantage of arms. Not one of the men ashore had a musket, and before they could get within range for pistol shooting, we flattered ourselves we should be able to give a good account of a half–dozen at least.

The squire was waiting for me at the stern window, all his faintness gone from him. He caught the painter and made it fast, and we fell to loading the boat for our very lives. Pork, powder, and biscuit was the cargo, with only a musket and a cutlass apiece for the squire and me and Redruth and the captain. The rest of the arms and powder we dropped overboard in two fathoms and a half of water, so that we could see the bright steel shining far below us us in the sun, on the clean, sandy bottom.

By this time the tide was beginning to ebb, and the ship was swinging round to her anchor. Voices were heard faintly halloaing in the direction of the two gigs; and though this reassured us for Joyce and Hunter, who were well to the eastward, it warned our party to be off.

Redruth retreated from his place in the gallery and dropped into the boat, which we then brought round to the ship’s counter, to be handier for Captain Smollett.

“Now, men,” said he, “do you hear me?”

There was no answer from the forecastle.

“It’s to you, Abraham Gray—it’s to you I am speaking.”

Still no reply.

“Gray,” resumed Mr. Smollett, a little louder, “I am leaving this ship, and I order you to follow your captain. I know you are a good man at bottom, and I dare say not one of the lot of you’s as bad as he makes out. I have my watch here in my hand; I give you thirty seconds to join me in.”

There was a pause.

“Come, my fine fellow,” continued the captain; “don’t hang so long in stays. I’m risking my life and the lives of these good gentlemen every second.”

There was a sudden scuffle, a sound of blows, and out burst Abraham Gray with a knife cut on the side of the cheek, and came running to the captain like a dog to the whistle.

“I’m with you, sir,” said he.

And the next moment he and the captain had dropped aboard of us, and we had shoved off and given way.

We were clear out of the ship, but not yet ashore in our stockade.

THIS fifth trip was quite different from any of the others. In the first place, the little gallipot of a boat that we were in was gravely overloaded. Five grown men, and three of them—Trelawney, Redruth, and the captain—over six feet high, was already more than she was meant to carry. Add to that the powder, pork, and bread–bags. The gunwale was lipping astern. Several times we shipped a little water, and my breeches and the tails of my coat were all soaking wet before we had gone a hundred yards.

“As though knowing could be any satisfaction to a man!

“But I went to work — like a slave. And I had hardly worked and thought about the matter six months before light came through one of the meshes suddenly — blindingly! I found a general principle of pigments and refraction — a formula, a geometrical expression involving four dimensions. Fools, common men, even common mathematicians, do not know anything of what some general expression may mean to the student of molecular physics. In the books — the books that tramp has hidden — there are marvels, miracles! But this was not a method, it was an idea, that might lead to a method by which it would be possible, without changing any other property of matter — except, in some instances colours — to lower the refractive index of a substance, solid or liquid, to that of air — so far as all practical purposes are concerned.”

“Phew!” said Kemp. “That’s odd! But still I don’t see quite ... I can understand that thereby you could spoil a valuable stone, but personal invisibility is a far cry.”

“Precisely,” said Griffin. “But consider, visibility depends on the action of the visible bodies on light. Either a body absorbs light, or it reflects or refracts it, or does all these things. If it neither reflects nor refracts nor absorbs light, it cannot of itself be visible. You see an opaque red box, for instance, because the colour absorbs some of the light and reflects the rest, all the red part of the light, to you. If it did not absorb any particular part of the light, but reflected it all, then it would be a shining white box. Silver! A diamond box would neither absorb much of the light nor reflect much from the general surface, but just here and there where the surfaces were favourable the light would be reflected and refracted, so that you would get a brilliant appearance of flashing reflections and translucencies — a sort of skeleton of light. A glass box would not be so brilliant, not so clearly visible, as a diamond box, because there would be less refraction and reflection. See that? From certain points of view you would see quite clearly through it. Some kinds of glass would be more visible than others, a box of flint glass would be brighter than a box of ordinary window glass. A box of very thin common glass would be hard to see in a bad light, because it would absorb hardly any light and refract and reflect very little. And if you put a sheet of common white glass in water, still more if you put it in some denser liquid than water, it would vanish almost altogether, because light passing from water to glass is only slightly refracted or reflected or indeed affected in any way. It is almost as invisible as a jet of coal gas or hydrogen is in air. And for precisely the same reason!”

“Yes,” said Kemp, “that is pretty plain sailing.”

“And here is another fact you will know to be true. If a sheet of glass is smashed, Kemp, and beaten into a powder, it becomes much more visible while it is in the air; it becomes at last an opaque white powder. This is because the powdering multiplies the surfaces of the glass at which refraction and reflection occur. In the sheet of glass there are only two surfaces; in the powder the light is reflected or refracted by each grain it passes through, and very little gets right through the powder. But if the white powdered glass is put into water, it forthwith vanishes. The powdered glass and water have much the same refractive index; that is, the light undergoes very little refraction or reflection in passing from one to the other.