"He has sent all but a few of his ships away, and we believe that they have returned to the frozen north for reinforcements. We who were on herd duty at the beginning of the investment are unable to return to the city, but we are continually harassing the warriors of Hin Abtol who are encamped upon the plain."

"So they are using equilibrimotors," I said; "it seems strange that any peoples from the frozen north should have these. They were absolutely unknown in Okar when I was there."

The equilibrimotor is an ingenious device for individual flying. It consists of a broad belt, not unlike the life belt used aboard passenger ships on Earth; the belt is filled with the eighth Barsoomian ray, or ray of propulsion, to a sufficient degree to equalize the pull of gravity and thus to maintain a person in equilibrium between that force and the opposite force exerted by the eighth ray. Attached to the back of the belt is a small radium motor, the controls for which are on the front of the belt; while rigidly attached to and projecting from the upper rim of the belt is a strong, light wing with small hand levers for quickly altering its position. I could understand that they might prove very effective for landing troops in an enemy city by night.

I had listened to Gan Hor with feelings of the deepest concern, for I knew that Gathol was not a powerful country and that a long and persistent siege must assuredly reduce it unless outside help came. Gathol depends for its food supplies upon the plains which comprise practically all of its territory. The far northwest corner of the country is cut by one of Barsoom's famous canals; and here the grains, and vegetables, and fruits which supply the city are raised; while upon her plains graze the herds that supply her with meat. And enemy surrounding the city would cut off all these supplies; and while Gahan doubtless had reserves stored in the city, they could not last indefinitely.

In discussing this with Gan Hor, I remarked that if I could get hold of a flier I'd return to Helium and bring a fleet of her mighty war ships and transports with guns and men enough to wipe Hin Abtol and his Panars off the face of Barsoom.

"Well," said Gan Hor, "your flier is here; it came with Hin Abtol's fleet. One of my men recognized it and your insigne upon it the moment he saw it; and we have all been wondering how Hin Abtol acquired it; but then, he has ships from a score of different nations, and has not bothered to remove their insignia."

"He found it in a courtyard in the deserted city of Horz," I explained; "and when he was attacked by green men, he made off in it with a couple of his warriors, leaving the others to be killed."