Alexander Kellas was educated at Aberdeen Grammar School and in 1889 went to Edinburgh to study for two years at the University and the Heriot-Watt College there. He then moved to University College, London, where he obtained his BSc in 1892. He already had a stepbrother in London, James N. F. Kellas; Alexander used to visit the family on Sunday evenings and later brought them small presents from Tibet and India.³

For a time Alexander Kellas was a Research Assistant at University College, London, with Sir William Ramsey, who worked on the chemistry of the noble gases. In 1895 Kellas went to Heidelberg University in Germany to study for his DPhil degree, which he received in 1897. He was appointed Lecturer in Chemistry at the Middlesex Hospital Medical School in London in 1900 and held that appointment until 1919. The University of London awarded him the degree of DSc in 1918.

Kellas developed an early love for hill walking. His brother Henry wrote to the Secretary of the Royal Geographical Society after Alexander’s death as follows⁴: “As a boy, the hills seemed to have a fascination for him, and he was ardently devoted to walking and climbing, first among the Grampians, and later on in Wales and on the continent. When he was only 14, he and a younger companion slept under the shelter stone in the Cairngorms, ascending Ben Macdhui and other mountains.” His first expedition to the Himalayas was in 1907, when he spent the months from August to October exploring mountains in Kashmir and Sikkim, the region of India north of Darjeeling and east of Mt. Everest. This was followed by further visits in the summers of 1909, 1911, 1912, 1913, 1914, and 1920 and the early spring of 1921.

It was impossible for Kellas to visit India between 1914 and 1918 because of the First World War. However, we know that he had planned expeditions to Sikkim to take place in both 1915 and 1916 because a typewritten proposal for these still exists. The proposal sets out an ambitious plan including making a large-scale map of the north and west approaches to Everest and obtaining a series of photographs showing the best prospects for climbing the mountain.

Kellas particularly explored the mountains of north Sikkim and thus became familiar with the approaches to the Everest region from the east and north [7]. He also spent some time in southern Tibet especially near the village of Kampa Dzong. Kellas was not a prolific writer but accounts of some of these expeditions were published in the Alpine Journal and the Geographical Journal [11–14, 16, 18, 19].

These explorations to extremely remote regions were carried out during the summer vacations, and it is remarkable that Kellas was able to find the time. The expeditions themselves lasted 3 or 4 months and at that time it would take some 3 weeks to sail from London to India and an additional 3 weeks to return. In spite of this, Kellas was described as a conscientious faculty member who was commended for his teaching [26]. However, there are indications in one of his letters of tensions between the medical school administration and himself over the amount of extra leave he requested for these expeditions.⁵

On most of these expeditions, Kellas went alone accompanied only by some native porters. Occasionally he had an English companion; for example, Henry Morshead accompanied him on his expedition to Kamet in 1920. Kellas was apparently the first Himalayan explorer to recognize the immense value of the Sherpas, the people of Tibetan origin who live near Mt. Everest, to exploration in these regions [27]. Since his early contact with the Sherpas, they have played critical roles in expeditions to Everest and other Himalayan mountains.

From a physical point of view, Kellas must have been remarkably tough to withstand the rigors of these small expeditions to remote areas at great altitudes. It is believed that he probably made more ascents over 20,000 ft than anyone else [26]. However, his appearance belied his athletic abilities. The well-known British climber, George Leigh Mallory, described him in a letter to his wife during the early stages of the 1921 Everest reconnaissance expedition thus: “Kellas I love already. He is beyond description Scotch and uncouth in his speech—altogether uncouth. He arrived at the great dinner party 10 min after we had sat down, and very dishevelled, having walked in from Grom, a little place four miles away. His appearance would form an admirable model to the stage for a farcical representation of an alchemist. He is very slight in build, short, thin, stooping, and narrow-chested; his head… made grotesque by veritable gig-lamps of spectacles and a long-pointed moustache. He is an absolutely devoted and disinterested person” [30].

The first two decades of this century were an exciting time in the physiology of extreme altitude. In the late 1900’s many people were of the opinion that ~ 21,500 ft (6,500 m) represented the maximum height attainable by humans. Kellas quotes the President of the Alpine Club, T. W. Hinchliff, who wrote in 1876 after visiting Santiago, Chile, as follows⁶ “I could not repress a strange feeling as I looked at Tupungato (21,550 ft) and Aconcagua (23,080 ft) and reflected that endless successions of men must in all probability be forever debarred from their lofty crests…. Those who, like Major Godwin-Austen, have had all the advantages of experience and acclimatization to aid them in attacks upon the higher Himalaya agree that 21,500 ft is near the limit at which man ceases to be capable of the slightest further exertion” [9].

However in 1909 the Duke of the Abruzzi led an expedition to the Karakorum that was designed “to contribute to the solution of the problem as to the greatest height to which man may attain in mountain climbing,” as the Duke’s biographer put it [4]. His party reached 7500 m (24,600 ft) without supplementary oxygen, far higher than anyone had been before. This feat astonished climbers and physiologists alike. The English physiologists Douglas, Haldane, and their co-workers [5] estimated from the reported barometric pressure of 312 Torr that the alveolar P_O2 was only 30 Torr, and they concluded that adequate oxygenation of the blood would be impossible under these conditions without active secretion in the lung. However, this conclusion was disputed by Marie Krogh [22], who had recently developed a technique for measuring the diffusion characteristics of the lung using carbon monoxide. She argued that Douglas and his colleagues had markedly underestimated the pulmonary diffusing capacity. This was just one of the exchanges between the two camps arguing for and against active secretion of oxygen by the lung in a controversy that lasted into the mid-1930’s.

Kellas had trained in chemistry, and he taught this subject to medical students at Middlesex Hospital Medical School for some 18 years. At this time, many students would have received relatively little chemistry before coming to medical school, and Kellas lectured in both inorganic and organic chemistry. His obituary in the Mddlesex Hospital Journal [25] refers to his great interest in teaching, especially to the weaker students, and he wrote three short textbooks to assist with his laboratory classes in chemistry.

Kellas’ early research was on various aspects of organic and inorganic chemistry. His DPhil thesis was devoted to the esterification of benzoic acids, and after his period with Sir William Ramsey, he studied the distribution of argon in human expired gas and in various vegetable and animal substances. He also carried out an extensive investigation on “The molecular complexity of liquid sulphur,” which was published in 1891.

Kellas gradually became increasingly interested in the physiology of high altitude, which was not surprising given his scientific background and his immense personal experience at extreme altitude. He became an authority on acute mountain sickness and contributed two short articles on this subject [20]. At one stage he even began studying to take a medical degree at the Middlesex Hospital Medical School⁷. In 1918 he collaborated with J. S. Haldane, one of the most eminent British physiologists of the day, on a study of acclimatization obtained by repeated exposures to low pressure in a chamber at the Lister Institute in London. A description of this work was published in the Journal of Physiology (London) and is referred to again below [8].

Although Kellas’ early Himalayan expeditions were primarily exploratory in nature, he became progressively more interested in using them to study the physiological problems of extreme altitude. At one stage he wrote a tentative proposal for a medical scientific expedition to remain for a period of several months at an altitude of 20,000 ft to study the physiology of acclimatization. In a letter to Hinks dated October 9, 1917¹, he suggested possible locations for a long-term camp, for example, the summit of Kanchenjhau (22,700 ft), and added “it might even be possible to drag up in small parts the framework of a small wooden hut.” He planned to carry out the types of experiments that Haldane and his colleagues had made on Pikes Peak. It is remarkable that such an expedition was not organized until over 40 years later, and even then the altitude was a more modest 19,000 ft. [28].

The major published contribution in the area of physiology by Kellas was his paper entitled “A consideration of the possibility of ascending the loftier Himalaya,” which was read at the meeting of the Royal Geographical Society on May 18, 1916, and subsequently published in the Geographical Journal [15]. The fact that the article was published in a geographical rather than physiological journal might indicate that Kellas thought of himself more as an explorer than a physiologist, although another factor may well have been that he received some financial support for his Himalayan expeditions from the Royal Geographical Society and presumably wanted to report his findings directly to them. The paper contains many features of interest that throw light on the state of high-altitude physiology at the time. For example, Kellas correctly predicts the barometric pressure on the summit of Mt. Everest to be 251 Torr (for a mean air temperature of 0 °C) based on the work of FitzGerald [6]. This correct value contrasts with later estimates made in the 1940’s, when the pressure was thought to be much lower based on the inappropriate use of the standard atmosphere.

The article in the Geographical Journal created a great deal of interest, particularly among climbers, and it was extensively reviewed in a subsequent issue of the Alpine Journal [15]. However, it is probable that Kellas’ choice of the Geographical Journal resulted in relatively few physiologists seeing the article, and this no doubt contributed to the fact that Kellas’ work is not well known.

Kellas’ most interesting study was entitled “A consideration of the possibility of ascending Mount Everest”. Although two complete manuscripts survive, one in the archives of the Royal Geographical Society and the other in the archives of the Alpine Club library,⁸ the paper was never published. One manuscript was sent to A. R. Hinks on April 24, 1920, at a time when Kellas was very busy preparing for what were to be his last two Himalayan expeditions. It is not clear why the manuscript was never published, although it may simply be that because he died abroad and never returned to England, no one pressed for publication. A French translation of the manuscript was published in a very obscure place, the proceedings of the Congres de l’Alpinisme held in Monaco in 1920 [17]. Kellas apparently presented the paper at this meeting when he was en route to India.⁹

Kellas begins by stating his main question: “Is it possible for man to reach the summit of Mount Everest without adventitious aids [by which he meant supple-mentary oxygen], and if not, does an ascent with oxygen appear to be feasible?” He divides the problems to be overcome into two groups: “I. Physical difficulties” and “II. Physiological difficulties,” and he considers each of these in considerable detail.

The introduction to the paper is interesting because he cites the altitude of Everest as 29,141 ft (8882 m). The official altitude at that time was 29,002 ft, having been determined by Sir Andrew Waugh, Surveyor-General of India, in 1852. Waugh succeeded Sir George Everest, the Surveyor-General after whom the mountain was named; this was when Everest was first identified as the highest mountain in the world. However, in 1909 Sir Sidney Burrard, a later Surveyor-General, recomputed the altitude from the original sightings but using different values for the refractive errors caused by the bending of light in the lower atmosphere, and he came up with the figure of 29,141 ft. It is not clear why Kellas preferred the higher altitude when most people accepted the official lower value. It was not until the 1950’s that D. L. Gulatee used new sightings to establish the now-accepted altitude of 29,028 ft (8848 m).

The first physical difficulty discussed by Kellas is that of access to the mountain. He points out that “The mountain has so far never been visited by white men, and it is unlikely that any mortal has reached an altitude of even 20,000 ft (6096 m) upon it.” However, with his unrivaled experience of the geography of the region, Kellas was able to suggest three possible routes from Darjeeling depending on whether the authorities of Tibet or Nepal gave permission. He believed the former to be more likely, which indeed proved to be true. Kellas’ knowledge of the area was supplemented by explorations made by Captain J. B. Noel, who at one stage disguised himself as a Tibetan to reconnoiter the Himalayan range east of Everest [24].

Kellas then goes on to discuss the best time of the year for an ascent. He correctly reasoned that the monsoon period would be impossible because of the heavy snowfall and recommended the months immediately preceding or succeeding the summer monsoon. These have proved to be the most suitable periods up to the present time. Kellas also considered possible routes on Everest itself. Here he was at a very considerable disadvantage because no climber had been anywhere near the mountain and available photographs were taken from many miles away. The two routes to the summit selected by Kellas were the east face and the northeast ridge. The latter was a good choice and was the route attempted by all the early expeditions from the north side, but the former proved to be exceptionally difficult and indeed was not climbed until 1983.¹⁰ Kellas also made the point that the climbing on Mt. Everest above an altitude of 26,500 ft looked easier than on some other Himalayan peaks such as Kanchenjunga, K2, and Nanga Parbat. In this he was correct.

Kellas’ most interesting studies from our point of view are in the section headed “Physiological difficulties.” He divided this section into four parts: (1) information from balloon ascents, (2) studies in low pressure chambers, (3) observations up to altitudes of 20,000 ft, and (4) the physiology of acclimatization to high altitude.

Under balloon ascents, Kellas briefly describes the experiences of the Englishmen Glaisher and Coxwell and the three Frenchmen led by Tissandier, who both ascended to altitudes near the summit of Mt. Everest. All five men lost consciousness, and in the ill-fated French ascent only Tissandier survived, the other two men dying from acute hypoxia. However, Kellas was quite clear that these dramatic consequences would not be expected during a climb up Mt. Everest because of the advantages coming from acclimatization. He also noted that even higher ascents in more recent times had been made safe by the balloonists inhaling oxygen.

The air chamber experiments fall into two categories. The acute exposure experiments gave results similar to those found in ballooning in that they also showed that humans could not survive the low barometric pressure on Mt. Everest without losing consciousness. Kellas quoted E. H. Starling’s influential textbook [31] which stated that “the lowest limit at which life is possible corresponds to an oxygen tension in the alveoli of 27–30 mm, which is distinctly above that calculated for Mt. Everest.” Parenthetically, recent work shows that these estimates are too low [34].

Kellas then briefly describes a very interesting set of experiments in which two subjects (J. S. Haldane and himself) spent 4 consecutive days in a low-pressure chamber at altitudes equivalent to 11,600, 16,000, 21,000, and 25,000 ft. This was the study referred to earlier [8] that was carried out at the Lister Institute in London and was apparently the only time that Kellas had an opportunity to collaborate with J. S. Haldane, one of the leading British high-altitude physiologists. Both subjects spent several hours in the chamber on each of the 4 days, and many interesting physiological observations were made. On the 4th day, when the pressure was only 312 Torr (corresponding to an altitude of 25,000 ft), Haldane’s alveolar P_CO2 was 19.8 and P_O2 30.1 Torr. Nevertheless he was able to cycle on the ergometer and do 3300 foot-pounds of work for 4 min but stopped because “he was exhausted and vision was becoming blurred.” This work rate corresponds to 456 kg.m.min⁻¹ which is not a great deal less than the 600 kg.m.min⁻¹ measured as the maximal work rate for subjects at an equivalent altitude after several weeks of acclimatization [33]. Administering oxygen at a low flow rate resulted in a dramatic improvement. Haldane stated: “The light seemed to increase and there was a short apnea. At the same time the lips and face became bright red.”