m exclaim, "_Donnerwetter!_"
half under his breath. But with a few careful turns of the wheel he
found the planet again, and moved him to the right part of the field.
Meanwhile the Full Moon shone on us with its pale glimmer. But a thin
rim of it next to the Earth gleamed brightly with rich silver light.

"I thought you said we had started in the dark of the Moon. I thought it
was behind the Earth," I interposed.

"That is the New Moon just emerging. It will probably not be seen on the
Earth until to-morrow night, but as we are at a greater distance we see
it first," replied the doctor.

"But that is not a New Moon, it is a Full Moon, which should not be seen
for fourteen days yet," I objected.

"Pardon me, it _is_ a New Moon," he insisted. "That inner rim of
brightness is all the sunlight she reflects. The paler glimmer is
Earth-light, which she reflects. When she is really a Full Moon, she
will be perfectly dark to us."

Then I explained to him the first umbrella appearance, and its gradual
swelling and final disappearance.

"Rainbow colours around the edge and a gradual changing of the shape,
you say? That means refraction. The Earth's atmosphere has been playing
tricks on you. The umbrella of dull red light was a refracted view of
the Moon before she really came into sight. Rays of light from the
hidden Moon were bent around to you. Then, as she gradually moved from
behind the Earth, her appearance was magnified by the convex lens formed
by the atmosphere, bent over that planet. Presently it diminished and
went out altogether, you say?"

"Yes, but that was because I steered away from her," I replied.

"No; you could hardly lose her so easily," he answered. "Did you ever
try holding an object behind a water-bottle or a gold-fish jar? There is
a place near the edge of the jar where a thing cannot be seen, though
the glass and water are perfectly transparent. The rays of light from
the object are bent around, through the glass and water, away from the
eyes of the observer. It was like that with the Moon when she
disappeared. She was really drawing out from the Earth all the time.
Finally, when her light passed beyond the atmosphere altogether, she
became suddenly visible in a different place and shining with another
colour. What we see now is the real Moon in her true place. The other
appearances were all tricks of refraction."

"But when I had turned away," I explained, "there came a thin rim of
bright ligh