It had been the south-western wall which had sustained damage, and now — I could not help myself — I glanced that way, but there was nothing to distinguish it, for the repair work had been thorough. Moses noted my glance, curiously, for he had not indicated which wall it had been.
“After this failure,” he went on, “I was still no closer to unraveling the mysteries of Plattnerite. Then, however” — his tone grew more animated — “I began to apply a little more reason to the case. The translucence is an optical phenomenon, after all. So — I reasoned — perhaps the key to the secrets of Plattnerite lay not in its chemistry, but in its optical properties.”
I felt a peculiar satisfaction — a kind of remote self-regard — at hearing this summary of my own clear thinking processes! And I could tell that Moses was enjoying the momentum of his own narrative: I have always enjoyed recounting a good tale, to whatever audience — I think there is something of the showman in me.
“So I swept aside my clutter of Schoolboy Chemistry,” Moses went on, “and began a new series of tests. And very quickly I came upon striking anomalies: bizarre results concerning Plattnerite’s refractive index — which, you may know, depends on the velocity of light within the substance. And it turned out that the behavior of light rays passing through Plattnerite is highly peculiar.” He turned to the experiment on the bench-top. “Now, look here; this is the clearest demonstration of Plattnerite’s optical oddities which I have been able to devise.”
Moses had set up his test in three parts, in a line. There was a small electric lamp with a curved mirror behind it, and, perhaps a yard away, a white screen, held upright by a retort stand; between these two, clamped in the claws of another retort, was a cardboard panel which bore the evidence of fine scoring. Beside the lamp, wires trailed to an electromotive cell beneath the bench.
The set-up was lucidly simple: I have always sought as straightforward as possible a demonstration of any new phenomenon, the better to focus the mind on the phenomenon itself, and not on deficiencies in the experimental arrangement, or — it is always possible — some trickery on behalf of the experimenter.
Now Moses closed a switch, and the lamp lit; it was a small yellow star in the candle-lit room. The cardboard panel shielded the screen from the light, save for a dim central glow, cast by rays admitted by the scoring in the panel. “Sodium light,” Moses said. “It is nearly a pure color — as opposed, say, to white sunlight, which is a mixture of all the colors. This mirror behind the lamp is parabolic, so it casts all the lamp’s light towards the interposed card.”
He traced the paths of the light rays towards the card. “On the card I have scored two slits. The slits are a mere fraction of an inch apart — but the structure of light is so fine that the slits are, nevertheless, some three hundred wavelengths apart. Rays emerge from the two slits” — his finger continued on “and travel onwards to the screen, here. Now, the rays from the two slits interfere — their crests and troughs reinforce and cancel each other out, at successive places.” He looked at me uncertainly. “Are you familiar with the idea? You would get much the same effect if you were to drop two stones into a still pond, and watch how the spreading ripples coalesced…”
“I understand.”
“Well, in just the same way, these waves of light — ripples in the ether — interfere with each other, and set up a pattern which one may observe, here on this screen beyond.” He pointed to the patch of yellow illumination which had reached the screen beyond the slits. “Can you see? — one really needs a glass — right at the heart of it, there, you’ll see bands of illumination and darkness, alternating, a few tenths of an inch apart. Well, those are the spots where the rays from the two slits are combining.”
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!
[5]
Honesty and Doubt
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!