For only an instant my curiosity was piqued, and then Ireplaced 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.
