Page:A princess of Mars.djvu/250

A PRINCESS OF MARS 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 on Mars is dependent upon the uninterrupted working of this plant.

One curious fact I discovered as I watched his [226]