process hinges on the use of the ninth ray, one of
the beautiful scintillations which I had noted emanating from the great
stone in my host's diadem.

This ray is separated from the other rays of the sun by means of finely
adjusted instruments placed upon the roof of the huge building,
three-quarters of which is used for reservoirs in which the ninth ray
is stored. This product is then treated electrically, or rather
certain proportions of refined electric vibrations are incorporated
with it, and the result is then pumped to the five principal air
centers of the planet where, as it is released, contact with the ether
of space transforms it into atmosphere.

There is always sufficient reserve of the ninth ray stored in the great
building to maintain the present Martian atmosphere for a thousand
years, and the only fear, as my new friend told me, was that some
accident might befall the pumping apparatus.

He led me to an inner chamber where I beheld a battery of twenty radium
pumps any one of which was equal to the task of furnishing all Mars
with the atmosphere compound. For eight hundred years, he told me, he
had watched these pumps which are used alternately a day each at a
stretch, or a little over twenty-four and one-half Earth hours. He has
one assistant who divides the watch with him. Half a Martian year,
about three hundred and forty-four of our days, each of these men spend
alone in this huge, isolated plant.

Every red Martian is taught during earliest childhood the principles of
the manufacture of atmosphere, but only two at one time ever hold the
secret of ingress to the great building, which, built as it is with
walls a hundred and fifty feet thick, is absolutely unassailable, even
the roof being guarded from assault by air craft by a glass covering
five feet thick.

The only fear they entertain of attack is from the green Martians or
some demented red man, as all Barsoomians realize that the very
existence of every form of life of Mars is dependent upon the
uninterrupted working of this plant.

One curious fact I discovered as I watched his thoughts was that the
outer doors are manipulated by telepathic means. The locks are so
finely adjusted that the doors are released by the action of a certain
combination of thought waves. To experiment with my new-found toy I
thought to surprise him into revealing this combination and so I asked
him in a casual manner how he had managed to unlock the massiv