we should have sufficient time to slacken speed at
the end of the journey. (See the chart.)

Mars was rapidly growing in size and brightness, for the distance
between the planet and the _Areonal_ was quickly diminishing as our
paths converged, and the various markings on its almost full round disc
formed the subject of continual observation and conversation. We had
noticed on several occasions a mistiness on some parts of the planet,
which I attributed to the vapours raised from the canals by the heated
atmosphere.

On the 21st of September, when we were all enjoying a smoke in the
"evening," and conversation had dragged somewhat, John started us off on
a fresh tack and gave us something to talk about for a very long time.

He winked at M'Allister and, looking at me with a knowing smile, said:
"Professor, as we are nearing our destination it might perhaps be well
if you now gave us some detailed information respecting the planet,
similar to that which you gave us when we were approaching the moon. It
would be both interesting and useful; for we should learn much more from
an orderly statement of the facts than we should from several long but
desultory conversations."

"Yes, Professor," chimed in M'Allister, "I'm quite ready to learn
something definite about Mars, for I can't say I really know much about
it at present."

"Very well then," I replied, "it is upon your own heads, and if you are
willing to listen to a rather long story, I am prepared to do the
talking. Please remember, however, that it will require some time to
make matters clear and understandable."

"Fire away, mon," cried M'Allister, "we will listen as long as you care
to talk."

So I began--"Mars, as no doubt you are aware, is a much smaller planet
than the earth, its diameter being only 4220 miles, which is a little
less than twice the diameter of our moon.

"It would require nine and a half globes the size of Mars to make one
globe the size of the earth; and even then it would not be so heavy,
because the average density of Mars is only about three-fourths of that
of the earth. Mars is the next planet outside the earth's orbit, so is
the fourth from the sun. The orbit in which Mars moves in its journey
round the sun is very much more eccentric than the earth's orbit; in
fact it is more eccentric than the orbits of any of the larger planets.
As a consequence, the planet's distance from the sun varies greatly
according to the particular part of