s the most favourable opposition in which to meet
him for the past quarter of a century. Back in the year 1877 he was only
about thirty-five million miles away, and it was then that we learned
most that we know of his physical features. But we shall not have a more
favourable time than this for the next seventeen years."

"Still it seems like nonsense to talk about travelling such an
incomprehensible distance, doesn't it?" I ventured.

"Not at all!" he replied positively. "If the Earth travels a million
miles per day in her orbit, without any motion being apparent to her
inhabitants, why should we not travel just as fast and just as
unconsciously? We are driven by the same force. The same engine of the
Creator's which drives all the universe, drives us. When we have left
the atmosphere we shall rush through the void of space without knowing
whether we are travelling at a thousand miles per minute or standing
perfectly still. Our senses will have nothing to lay hold on to form a
judgment of our rate of speed. But if we make an average of only five
hundred miles per minute we shall accomplish the distance in about fifty
days, and arrive soon after opposition."

"But have you given up stopping on the Moon?" I asked. "I had great
hopes of making those rich discoveries there."

"We must leave all that until our return trip. I have chosen this
starting time in the dark of the Moon in order to have the satellite on
the other side of the Earth and out of the way. She would only impede
our progress, as we wish to acquire a tremendous velocity just as soon
as we leave the atmosphere. We must accelerate our speed as long as
gravity will do it for us. When we can no longer gain speed, we shall
at least continue to maintain our rapid pace.

"But if we stopped on the Moon, we should only have her weak gravity to
repel us towards Mars, and we could make but little speed. On our
return, the stop on the Moon will be a natural and easy one. We shall be
near home and can afford to loiter."

While the doctor was saying this, he had been busy making tests of his
apparatus. He now called me to see his buoyancy gauge, which was a
half-spherical mass of steel weighing just ten pounds. It was pierced
with a hole at right angles to its plane surface and strung upon a
vertical copper wire. Small leaden weights, weighing from an ounce to
four pounds each, were provided to be placed upon the plane surface of
the steel. The doctor explained it