The cylinders containing our oxygen were found to be in good condition; but the apparatus—through no fault of the makers, who had, indeed, done their work admirably—leaked very badly, and to get them into satisfactory working order, four days of hard toil with soldering-iron, hacksaw, pliers, and all the other paraphernalia of a fitter’s shop were necessary. Our workshop was in the open. The temperature played up and down round about 0° F., but inclined more to the negative side of that irrational scale. The masks from which the oxygen was to be breathed proved useless, but by tackling the problem with a little thought and much cheerfulness a satisfactory substitute was eventually evolved, making it possible to use the oxygen apparatus in an efficient manner. Without this new mask no real use could have been made of our oxygen supplies; oxygen would have been misjudged as being useless, and the solution of the problem of climbing Mount Everest would have been as distant as ever. Preparatory to embarking on the climb itself, we went for several trial walks—one over to the Rapiu La, a pass 21,000 feet high, at the foot of the North-east ridge of Everest, from which we hoped to obtain views of the country to the south. But only part of the North-east ridge showed hazily through drifting mists. Towards the north and looking down the East Rongbuk Glacier, views were clearer, though partially obscured by rolling banks of cloud. Colonel Strutt and Dr. Wakefield, unoxygenated, accompanied us on this little expedition, and oxygen at once proved its value, so easily did Bruce and I outpace them. On May 22, acting on instructions from Colonel Strutt, Geoffrey Bruce, Wakefield, Tejbir, and I, with a number of porters, set out for the North Col to meet and afford any required assistance to the members of the first climbing party who were on their way down from the mountain. It was also our intention to bring stores up into the North Col as well as give the oxygen apparatus a final severe try-out prior to embarking upon an attack upon Mount Everest itself. We met the first climbing party just above the foot of the final steep slopes leading up to the North Col. They were more or less in the last stage of exhaustion, as, indeed, men who have done their best on such a mountain should be. After supplying them with what liquid nourishment was available, and leaving Wakefield and two porters to see them back to Camp III, we carried on up to the North Col. In the afternoon we returned to Camp III. There had been a considerable amount of step-cutting, for fresh snow had fallen, compelling us to deviate from the usual route; but even so, oxygen had made a brief Alpine ascent of what is otherwise a strenuous day’s work. We took three hours up and fifty minutes down, with thirty-six photographs taken _en route_. [Illustration: EAST RONGBUK GLACIER NEAR CAMP II. ]