Moses straightened up. “This interference is a well-known effect. Such an experiment is commonly used to determine the wavelength of the sodium light — it works out at a fifty-thousandth part of an inch, if you’re interested.”

“And the Plattnerite?” Nebogipfel asked.

Moses started at hearing the Morlock’s liquid tones, but he carried on gamely. From another part of the bench he produced a glass slide, perhaps six inches square, held upright in a stand. The glass appeared to be stained green. “Here I have some Plattnerite — actually, this slide is a sandwich of two glass sheets, with the Plattnerite sprinkled and scattered between — do you see? Now, watch what happens when I interpose the Plattnerite between card and screen…”

It took him some adjusting, but he arranged affairs so that one of the slits in the cards remained clear, and the other was covered by the Plattnerite slide. Thus, one of the two interfering sets of rays would have to pass through Plattnerite before reaching the screen.

The image of interference bands on the screen was made fainter — it was tinged with green — and the pattern was shifted and distorted.

Moses said, “The rays are rendered less pure, of course some of the sodium light is scattered from the Plattnerite itself, and so emerges with wavelengths appropriate to the greener part of the spectrum but still, enough of the original sodium light passes through the Plattnerite without scattering to allow the interference phenomenon to persist. But — can you see the changes this has made?”

Nebogipfel bent closer; the sodium light shone from his goggles.

“The shifting of a few smears of light on a card may not seem so important to the layman,” Moses went on, “but the effect is of great significance, if analyzed closely. For and I can show you the mathematics to prove it,” he said, waving unconvincingly at a heap of notes on the floor, “the light rays, passing through the Plattnerite, undergo a temporal distortion. It is a tiny effect, but measurable — it shows up in a distortion of the interference pattern, you see.”

“A ’temporal distortion’?” Nebogipfel said, looking up. “You mean…”

“Yes.” Moses’s skin was coldly illuminated in the sodium light. “I believe that the light rays — in passing through the Plattnerite — are transferred through time.”

I gazed with a sort of rapture at this crude demonstration, of bulb and cards and clamps. For this was the start — it was from this naive beginning that the long, difficult experimental and theoretical trail would lead, at last, to the construction of the Time Machine itself!

I could not betray how much I knew, of course, and I did my best to simulate surprise and shock at his pronouncement. “Well,” I said vaguely, “well — Great Scott…”

He looked at me, dissatisfied. He was evidently forming the opinion that I was something of an unimaginative fool. He turned away and began to tinker with his apparatus.

I took the opportunity to draw the Morlock to one side. “What did you make of that? An ingenious demonstration.”

“Yes,” he said, “but I am surprised he has not noticed the radioactivity of your mysterious substance, Plattnerite. The goggles show clearly—”

“Radio-activity?”

He looked at me. “The term is unfamiliar?” He gave me a quick survey of this phenomenon, which involves, it seems, elements which break up and fly into pieces. All elements do this — according to Nebogipfel — at more or less perceptible rates; some, like radium, do it in a manner spectacular enough to be measurable — if one knows what to look for!

All this stirred up some memories. “I remember a toy called a spinthariscope,” I told Nebogipfel. “Where radium is held in close proximity to a screen, coated with sulphide of zinc—”

“And the screen fluoresces. Yes. It is the disintegration of the cores of radium atoms which causes this,” he said.

“But the atom is indivisible — or so it is thought—”

“The phenomenon of subatomic structure will be demonstrated by Thomson at Cambridge, no more than a few years — if I recall my studies — after your departure into time.”

“Subatomic structure — by Thomson! Why, I’ve met Joseph Thomson myself, several times — a rather pompous buffer, I always thought — and only a handful of years younger than me…”

Not for the first time I felt a deep regret at my precipitate plummeting into time! If only I had stayed to take part in such intellectual excitement — I could have been at the thick of it, even without my experiments in time travel — surely that would have been adventure enough, for any one lifetime.

Now Moses seemed to be done, and he reached out to turn off the sodium lamp — but he snatched his hand back with a cry.

Nebogipfel had touched Moses’s fingers with his own, hairless palm. “I am sorry.”

Moses rubbed his hand, as if trying to wipe it clean. “Your touch,” he said. “It’s so — cold.” He stared at Nebogipfel as if seeing him, in all his strangeness, for the first time.

Nebogipfel apologized again. “I did not mean to startle you. But—”

“Yes?” I said.

The Morlock reached out with one worm-like finger, and pointed at the slab of Plattnerite. “Look.”

With Moses, I bent down and squinted into the illuminated slab.

At first I could make out nothing but the speckled reflection of the sodium bulb, a sheen of fine dust on the surface of the glass slides… and then I became aware of a growing light, a glow from deep within the substance of the Plattnerite itself: a green illumination that shone as if the slide was a tiny window into another world.

The glow intensified further, and evoked glittering reflections from the test tubes and slides and other paraphernalia of the laboratory.

We retired to the dining-room. It was now long hours since the fire had died, and the room was growing chilly, but Moses did not show any awareness of my discomfort. He, supplied me with another brandy, and I accepted an offer of a cigar; Nebogipfel asked for some clear water. I lit up my cigar with a sigh, while Nebogipfel watched me with what I took to be blank astonishment, all his acquired human mannerisms forgotten!

“Well, sir,” I said, “when do you intend to publish these remarkable findings?”

Moses scratched his scalp and loosened his gaudy tie. “I’m not certain,” he said frankly. “What I have amounts to little more than a catalogue of observations of anomalies, you know, of a substance whose provenance is uncertain. Still, perhaps there are brighter fellows than me out there who might make something out of it learn how to manufacture more Plattnerite, perhaps…”

“No,” Nebogipfel said obscurely. “The means to manufacture radio-active material will not exist for another several decades.”

Moses looked at the Morlock curiously, but did not take up the point.

I said bluntly, “But you’ve no intention of publishing.”

He gave me a conspiratorial wink — another grating mannerism! — and said, “All in good time. You know, in some ways I’m not quite like a True Scientist — you know what I mean, the careful, miniature sort of chap who ends up known in the Press as a ’distinguished scientist.’ You see such a chap giving his little talk, on some obscure aspect of toxic alkaloids, perhaps, and floating out of the magic-lantern darkness you might hear the odd fragment the chap imagines himself to be reading audibly; and you might catch a glimpse of gold-rimmed spectacles and cloth boots cut open for corns…”

I prompted, “But you—”

“Oh, I’m not meaning to decry the patient plodders of the world! — I daresay I have my share of plodding to do in the years to come — but I also have a certain impatience. I always want to know how things turn out, you see.” He sipped his drink. “I do have some publications behind me — including one in the Philosophical Transactions and a number of other studies which should yield papers. But the Plattnerite work…”