Soon after we reached these remote regions of eternal light, we began to experience considerable difficulty in breathing. At times this became so bad, that all of us lapsed into a state of semi-stupor. This caused us the gravest anxiety and alarm, and as we sped onwards the trouble increased. Clearly something was going wrong. The terrible thought that air was absolutely about to fail us, in spite of all the Doctor's careful experiments and calculations, filled us with thoughts too horrible to express. The condensers worked admirably, but driven at their utmost capacity, they still failed to furnish sufficient breathable atmosphere. Singularly enough, poor Rover felt this diminishing supply of air far more than his human companions, and for hours scarcely moved or breathed. The Doctor was puzzled, Graham was perplexed, Temple and Sandy very much depressed--the latter especially so. After many careful experiments and a thorough examination of the _Sirius_, we at last found the cause in a loosened window. The remedying of this necessitated one of us going out on to the balcony and climbing the corniced sides. Graham volunteered the hazardous duty. The Doctor, with his usual forethought, and showing how well he had planned-out his gigantic scheme to the very smallest detail, and how carefully he had provided for all the contingencies human intelligence could foresee, had brought with him a modified diver's helmet, with the air-tubes attached, and a small cock-tap was fastened in the side of the _Sirius_, through which air-pipes could be passed. This apparatus we adjusted on Graham's head, and round his body hung a coil of fine manilla rope. Our speed was now considerably reduced. While the Doctor assisted him to mount the ladder which led to the door, and opened and closed it as he went through on to the balcony, Temple and Sandy worked the pumps which supplied him with air. This door had to be closed very quickly, to prevent our own air escaping. We eventually heard him at work on the defective window, and the great improvement in the air of our chambers was sufficient evidence that he had succeeded in his task. Still, he did not return; for quite ten minutes we were in the greatest suspense as to his movements. The air-pipes had been drawn out nearly to their fullest extent, which was a singular circumstance, and one that seemed to bode no good, as half their length was amply sufficient for Graham's needs. Our concern rapidly grew into absolute alarm for the safety of our companion, until at last we had the signal that he was waiting to be admitted. It was a welcome relief to us all, and Sandy could not refrain from uttering cheer after cheer of welcome, forgetting his work of pumping until sternly called to his duty by the Doctor. As soon as the door was opened, poor Graham fell into the Doctor's arms, and for several hours he lay unconscious, in spite of all our remedies and careful treatment. Something had happened, and for