The main question for Mallory and Irvine’s climb in terms of the oxygen is whether they went with 2 bottles or 3 bottles each. An excellent source of information on the various oxygen systems and bottles used on Everest, is Detectives on Everest by Jochen Hemmleb and Eric Simonson because it covers not only the 1924 systems, but also the bottles used by later expeditions. It also sheds some light on “Bottle #9”, a 1924 bottle that was found between the First Step and the ice axe. The “Mallory and Irvine Research Expeditions” uncovered a wealth of information, but it is important to distinguish factual evidence that they uncovered as opposed to opinions expressed by different members of the team.
For instance, when Jake Norton (no relation to E.F. Norton from the 1924 expedition) and Brent Okita located Camp VI at 26,700ft, it resolved the conflicting accounts of its altitude. Odell had reported it at 27,000 and implied that Mallory had moved it further up the ridge, but Okita and Norton photographed it at 26,700. Whether Mallory moved it up the ridge or not remains unanswered — as there is no record of whether Norton’s initial placement of the camp was lower.
The basic theory of Detectives on Everest, is that Mallory and Irvine attempted to climb the Second Step along a full north-east arete route. My analysis differs regarding which route Mallory took, but I still use all the facts and evidence they uncovered on the mountain — for the most part. For instance, Jake Norton found a mitten along the ridge. I do not assign any weight to that evidence. There are a variety of ways it could have gotten there and it does help to prove or disprove any of the various theories.
The basics facts of the oxygen bottles can be found in this article about the 1999 Mallory and Irvine Research Expedition by Eric Simonson. An interesting item that they uncovered was the Mallory had a list of 5 oxygen cylinders on a note found on his body. Jochen Hemmleb noted that a sixth might have been omitted if it held a full charge of 120 atmospheres — all the other cylinders listed either 100 and 110. In a different article Hemmleb questions whether a “compromise” solution was used — with Irvine carrying 3 bottles and Mallory 2. That is certainly a possibility, but it does not really change the analysis. In that case, Irvine would cache his first bottle at about the 3 hour mark and Irvine would turn his oxygen on at that point and they would then continue in sync. As a note, Irvine was a little taller than Mallory’s 6 feet and looked a little more muscular. As such, the extra weight would not be as big a deal and his body would naturally require more oxygen due to the size.
Mallory had the porters carry up a total of 6 oxygen bottles to the high camp, and Mallory and Irvine left North Col carrying two bottles each, as seen in the final still photograph taken of the pair. Mallory’s note indicates that he made it to high camp on 90 atmospheres (a little less than one bottle), so the oxygen inventory at arrival to high camp was 10 bottles, 2 empty and 8 full. That night, they would have slept using half a bottle each which left exactly 6 full bottles for a summit attempt. As Mallory had to go to great lengths to get the porters to carry the bottles up, it is not likely that he had them carry bottles he did not intend on using.
The location of Oxygen Bottle #9 is only consistent with at least one climber using a 3 bottle caching strategy.
Oxygen Bottle #9 was located approximately “170-180 m horizontally away from the top of the First Step, at an altitude of c. 8470-8475m”. (See Hemmleb’s analysis). As the ice-axe was 250 yards from the First Step, the bottle would be approximately 160 feet (50m) from the ice axe +/- 50 feet to account for potential differences in the “First Step” — that is, the bottle was closer to the ice axe than it was to the First Step.
Any 1924 oxygen bottle found below the First Step is only consistent with them taking 3 bottles from Camp VI. Obviously, there are extreme examples to the contrary. For instance, Mallory and Irvine could have climbed up to the bottle location with one bottle, had tea, left the bottle, and turned around and in a short distance they had an unfortunate accident. However, in terms of realistic scenarios, it can be broken down as follows:
M&I depart with 2 bottles each and do not turn it on immediately. They realized that the climb will take them longer than the 2 bottles will last and want the oxygen for higher up.
M&I depart with 2 bottles each and go on oxygen immediately. In this case, they believe that can make the summit on the 2 bottles.
M&I depart with 3 bottles each. The oxygen would be turned on.
M&I depart with 2 bottles for Mallory and 3 bottles for Irvine. Irvine’s oxygen in on.
The bottle is too close to have been dropped on the ascent.
Looking at the reports from the 1933 expedition, we know exactly how long the climb from Camp VI (1924) to the First Step took for people without oxygen and carrying heavy loads (at least part of the way). Wyn Harris and a group of porters started out from Camp V (25,260) at 8:00AM. They were carrying all the equipment and provisions up to establish the new Camp VI (1933). Along the way, they passed the old Camp VI (1924) at 26,700 and proceed up to the new location at 27,400. They arrived at 27,400 at 1:30 PM for an entire trip of 5.5 hours. Wyn reported the climb time below 27,000ft as 400ft/hr but noted it got slower after that. With a little basic math, we can figure out that the climb time above 27,000ft was about 350ft/hr. So after old Camp VI (1924), 300 vertical feet were climbed at 400ft/hr and 400 vertical feet were climbed at 350ft/hr to get to new Camp VI (1933). This gives 1.64 hours from old Camp VI to new Camp VI.
For the second leg of the trip, Wyn listed his climb time from new Camp VI (1933) to the First Step as 1 hours, 20 minutes (1.33 hr). The climb from Camp VI (1933) to the ice axe was approximately 1 hour.
This means that a party carry loads below new Camp VI (1933) and then proceeding normally to the First Step took a total of 3 hours. None of these climbers were using oxygen. In contrast, M&I used oxygen the whole way from Camp IV.
Turning to our “realistic scenarios,” under (1) — don’t use oxygen immediately, M&I would not turn their oxygen on until after the First Step. If they then used a bottle cache strategy on the two bottles, they would not turn the O2 on for another 2.5 hours. As such, there is no reason they would drop a bottle below the First Step, and all bottles dropped on the decent would also be at or above the First Step. That is, if you turned oxygen on at the first step and and climbed for 4 hours, dropped a bottle, climbed for 1 more hour, turned around and headed back, you would be at or above the First Step at the time you ran out of your second bottle. Any other scenarios (such as climbing for 3 hours and then turning around) are not realistic.
Under (2) — carrying 2 bottles, max oxygen flow right out of camp. Under this scenario, the oxygen bottle would last 4 hours. They would be well beyond the First Step at the time. Wyn Harris’ group was carrying loads for 1/2 of the trip and had oxygen for none of it. It is not believable that Mallory would take 4 hours using oxygen to get to a location Harris got to in less than 3 hours. Harris was at the First Step at the 3 hour mark and Bottle #9 was below the First Step. Exactly how much lower, we don’t know, but anything lower basically has Mallory with oxygen climbing at 60% of the speed of Harris without oxygen. That is not realistic. A a slight variation on this would be Mallory carrying 2, Irvine 3, non-caching — that is, use the oxygen until it is empty and then drop the bottle. Under this variation, bottle #9 would not be dropped first. Bottle #100 was the least full, as noted by Mallory on the envelope he was carrying. Using a simple “carry them until they are empty” strategy, you would start with the least full bottle so that you could discard the extra weight sooner.
Under (3) — carrying 3 bottles. Under this scenario, there are a variety of ways that an oxygen bottle got to that location. It could have been left on the way up as a bottle cache. Typically, this would mean that two bottles would be cached, but one of the bottles might have fallen in the 60+ years prior to it being found. More likely, it would have been dropped on the descent, as that location would line up with the timeline outlined in the video.
Under (4) — Mallory with 2, Irvine with 3. This is similar to (3) except that Mallory would not use oxygen for the first 2.5 hours and last 2.5 hours of the trip. Mallory would not discard any bottles below the First Step. He would switch his oxygen on 2.5 hours before the second cache point, cache a 1/2 bottle at the second point, summit and back on a single bottle, discard the empty bottle far above the First Step (close to the Third), use his cached 1/2 bottle, and discard that at or above the First Step.
Any “final bottle” would result in the entire rig being dropped. The apparatus was fairly heavy — about 4 lbs. There were multiple sets, and Mallory had already discarded a broken system down between Camps IV and V on a earlier climb. Odell found the rig and brought it to Camp V where he tried unsuccessfully to get it working. The notion that Irvine would want to keep the system so that he had a example is not realistic because he had working systems down in the lower camps, all of which he personally modified. As such, there would be no need to carry down an apparatus, and Irvine had already abandoned a broken apparatus, so he had no qualms about leaving them on the mountain.
The oxygen “rig” most likely used by Mallory and Irvine likely discarded the entire aluminum frame and just carried the bottles in a back pack — the way the porters carried the bottles up and the way every climber on Everest today climbs. There was no need for the frame, and Irvine likely modified the apparatus to discard the entire frame. This was noted by Odell when he noted the various pieces of the frame left in the camp. As such, the “rig” would consist of just the regulator and attaching tubes.
Mallory’s body did not have an oxygen apparatus strapped to it. It also only had one boot on. It is possible that Mallory fell while walking down the mountain with one boot and no oxygen, but it is more likely that those items came off in the 1000+ foot fall. It is also possible that Mallory was carrying only 2 bottles initially, with Irvine carrying 3. In that case, Mallory would have discarded his apparatus around the First Step when his final bottle ran out. Because no oxygen rig was found by the 1933 expedition even though they found an ice axe, it is an indication that neither Mallory nor Irvine had discarded their rigs yet.
In terms of the 1000+ foot fall, there has been some speculation about “broken up” bodies. The theory is that people who fall from high on the ridge have “broken up” bodies, while Mallory’s body was not “broken up.” Therefore, he could not have fallen from high on the ridge. I will only note that people do not always fall immediately. Some people sit down and die high on the ridge. Shortly thereafter, they become frozen solid. Later, the wind, snow, etc. causes them to fall down the ridge where their bodies become “broken up.” This is just speculation, but I suspect that a frozen body would be more inclined to break up than a warm body. As such, I do not assign any weight to the “broken up” bodies theory. It should also be noted that Mallory’s body was seriously injured. At some point, he fell with enough force to create a compound fracture of his leg.
The “Sherpa moved it” theory. Under this theory, Bottle #9 was originally up higher, but someone picked it up and moved it down the mountain at an unknown time for an unknown reason. First, this largely would not make any difference. As noted, any bottle dropped at or below the First Step is only consistent with a 3 bottle system. In terms of the Chinese climbers, they were generally following the ridge route up the First Step so there would not be any 1924 bottles above the First Step on the “modern route.” The route below the ridge but beyond the First Step was climbed by Wyn and another team in 1933. There were no obvious oxygen bottles along the route in 1933, so it is not clear how a Sherpa would see them in subsequent years. When the bottle was found, it was in a crack that was not easily visible. If the bottle was originally in a more obvious location higher up the route, then Wyn Harris’ group would have seen it in 1933. In terms of the conspiracy theory that the bottle was found close to the Third Step and then moved down the mountain as part of a “cover up.” If that were the case, it would be much easier to simply drop it off the Kangshung face.
The “Sherpa moved it, Theory 2.” Under this theory, a Sherpa found a bottle “sticking out of the snow below the exit from the Yellow Band” — which I take to mean the “exit cracks” along the standard route. The Sherpa then moved the bottle higher. Later, Tap Richards recovered a bottle on the descent but it is not clear whether this was the same bottle previously moved by the Sherpa. This scenario , if true, would prove the bottle caching theory. The only reasonable way a bottle would be at the exit cracks would be if it was cached there on the ascent. As they did not make it back to the exit cracks on their descent, the bottle would have remained there. Under this scenario, there were likely the two bottles, and Hemmleb mentions that possibility in his analysis. The reason is that the bottle by the “exit cracks” would not be bottle #9 — it would be bottle #100, as that scenario matches with Mallory carrying 2 and Irvine carrying 3 — it is also possible that there were originally 2 bottles there but one of them rolled down at some point. Irvine would cache the first bottle after 2 hours climbing and they would anticipate an 8 hour round trip from that point. Unfortunately, we will likely never know exactly where each oxygen bottle was, but the mere fact that a 1924 bottle was recovered from somewhere below the First Step essentially confirms the bottle cache theory. In addition, finding two different bottles is also consistent with the bottle cache theory. Finding two bottles is not consistent with a 2-bottle non-caching theory. That is, if both Mallory and Irvine had fully exhausted a bottle — one at the exit cracks, and one 170m meters from the base of the First Step, then 50% of their oxygen was expired and they had no hope of completing the climb. Even if they did try to “explore the ridge” or “explore the second step,” they would do so and then turn around at or before running out of oxygen and return to camp — the exact same way that every other group of climbers turned around after realizing there was no hope of making the summit.
For Mallory & Irvine, the simple theories work. Mallory and Irvine, using oxygen, climbed at or above the rate of climbers doing the exact same route without oxygen. They used a common sense bottle caching system to reduce the weight. Under this system, they would discard their second bottle at about the 12-13 hour mark. Going from Camp VI (1924) to the summit and back via the “zig-zag” route would put them on the descent just below the First Step at about the 12-13 hour mark, at which point one of them discarded a finished bottle. The bottle sat there until it was retrieved by the Mallory and Irvine Research Expedition.