Hastily I dumped the contents of my pocket-pouch upon the ground before me. Could I but find a slender bit of steel I might yet fashion a key that would give me ingress to the temple prison.

As I examined the heterogeneous collection of odds and ends that is always to be found in the pocket-pouch of a Martian warrior my hand fell upon the emblazoned radium flash torch of the black dator.

As I was about to lay the thing aside as of no value in my present predicament my eyes chanced upon a few strange characters roughly and freshly scratched upon the soft gold of the case.

Casual curiosity prompted me to decipher them, but what I read carried no immediate meaning to my mind. There were three sets of characters, one below another:

3 |-| 50 T 1 |-| 1 X 9 |-| 25 T

For only an instant my curiosity was piqued, and then I replaced the torch in my pocket-pouch, but my fingers had not unclasped from it when there rushed to my memory the recollection of the conversation between Lakor and his companion when the lesser thern had quoted the words of Thurid and scoffed at them: "And what think you of the ridiculous matter of the light? Let the light shine with the intensity of three radium units for fifty tals"-ah, there was the first line of characters upon the torch's metal case-3-50 T; "and for one xat let it shine with the intensity of one radium unit"-there was the second line; "and then for twenty-five tals with nine units."

The formula was complete; but-what did it mean?

I thought I knew, and, seizing a powerful magnifying glass from the litter of my pocket-pouch, I applied myself to a careful examination of the marble immediately about the pinhole in the door. I could have cried aloud in exultation when my scrutiny disclosed the almost invisible incrustation of particles of carbonized electrons which are thrown off by these Martian torches.

It was evident that for countless ages radium torches had been applied to this pinhole, and for what purpose there could be but a single answer-the mechanism of the lock was actuated by light rays; and I, John Carter, Prince of Helium, held the combination in my hand-scratched by the hand of my enemy upon his own torch case.

In a cylindrical bracelet of gold about my wrist was my Barsoomian chronometer-a delicate instrument that records the tals and xats and zodes of Martian time, presenting them to view beneath a strong crystal much after the manner of an earthly odometer.

Timing my operations carefully, I held the torch to the small aperture in the door, regulating the intensity of the light by means of the thumb-lever upon the side of the case.

For fifty tals I let three units of light shine full in the pinhole, then one unit for one xat, and for twenty-five tals nine units. Those last twenty-five tals were the longest twenty-five seconds of my life. Would the lock click at the end of those seemingly interminable intervals of time?

Twenty-three! Twenty-four! Twenty-five!

I shut off the light with a snap. For seven tals I waited-there had been no appreciable effect upon the lock's mechanism. Could it be that my theory was entirely wrong?

Hold! Had the nervous strain resulted in a hallucination, or did the door really move? Slowly the solid stone sank noiselessly back into the wall-there was no hallucination here.

Back and back it slid for ten feet until it had disclosed at its right a narrow doorway leading into a dark and narrow corridor that paralleled the outer wall. Scarcely was the entrance uncovered than Woola and I had leaped through-then the door slipped quietly back into place.

Down the corridor at some distance I saw the faint reflection of a light, and toward this we made our way. At the point where the light shone was a sharp turn, and a little distance beyond this a brilliantly lighted chamber.

Here we discovered a spiral stairway leading up from the center of the circular room.

Immediately I knew that we had reached the center of the base of the Temple of the Sun-the spiral runway led upward past the inner walls of the prison cells. Somewhere above me was Dejah Thoris, unless Thurid and Matai Shang had already succeeded in stealing her.

We had scarcely started up the runway when Woola suddenly displayed the wildest excitement. He leaped back and forth, snapping at my legs and harness, until I thought that he was mad, and finally when I pushed him from me and started once more to ascend he grasped my sword arm between his jaws and dragged me back.

No amount of scolding or cuffing would suffice to make him release me, and I was entirely at the mercy of his brute strength unless I cared to use my dagger upon him with my left hand; but, mad or no, I had not the heart to run the sharp blade into that faithful body.

Down into the chamber he dragged me, and across it to the side opposite that at which we had entered. Here was another doorway leading into a corridor which ran directly down a steep incline. Without a moment's hesitation Woola jerked me along this rocky passage.

Presently he stopped and released me, standing between me and the way we had come, looking up into my face as though to ask if I would now follow him voluntarily or if he must still resort to force.

Looking ruefully at the marks of his great teeth upon my bare arm I decided to do as he seemed to wish me to do. After all, his strange instinct might be more dependable than my faulty human judgment.

And well it was that I had been forced to follow him. But a short distance from the circular chamber we came suddenly into a brilliantly lighted labyrinth of crystal glass partitioned passages.

At first I thought it was one vast, unbroken chamber, so clear and transparent were the walls of the winding corridors, but after I had nearly brained myself a couple of times by attempting to pass through solid vitreous walls I went more carefully.

We had proceeded but a few yards along the corridor that had given us entrance to this strange maze when Woola gave mouth to a most frightful roar, at the same time dashing against the clear partition at our left.

The resounding echoes of that fearsome cry were still reverberating through the subterranean chambers when I saw the thing that had startled it from the faithful beast.

Far in the distance, dimly through the many thicknesses of intervening crystal, as in a haze that made them seem unreal and ghostly, I discerned the figures of eight people-three females and five men.

At the same instant, evidently startled by Woola's fierce cry, they halted and looked about. Then, of a sudden, one of them, a woman, held her arms out toward me, and even at that great distance I could see that her lips moved-it was Dejah Thoris, my ever beautiful and ever youthful Princess of Helium.

With her were Thuvia of Ptarth, Phaidor, daughter of Matai Shang, and Thurid, and the Father of Therns, and the three lesser therns that had accompanied them.

Thurid shook his fist at me, and then two of the therns grasped Dejah Thoris and Thuvia roughly by their arms and hurried them on. A moment later they had disappeared into a stone corridor beyond the labyrinth of glass.

They say that love is blind; but so great a love as that of Dejah Thoris that knew me even beneath the thern disguise I wore and across the misty vista of that crystal maze must indeed be far from blind.