THE HEIGHT OF MOUNT EVEREST A NEW DETERMINATION (1952-5)

B. L. GULATEE

With the consent of the Director of Geodetic and Research W Branch of the Survey of India, Dr. B. L. Gulatee, the following extracts from Technical Paper No. 8, 1954, are reproduced.

The height now accepted by the Survey of India is given as 29,028 feet. But this figure does not appear to have been universally agreed on. And some criticism has been made of the said pamphlet, not so much as to the results set forth but in certain minor respects. The 'Doctors' however have not actually disagreed.

The weighted mean value of the height of Mount Everest works out to be 29,028 feet with a probable error of ± o.8 feet. This probable error is derived from internal evidence alone and is likely to be too small on account of the presence of systematic errors. Bearing in mind the various possible sources of error, it is considered that the odds are 20 to 1 against this value being in error by more than 10 feet.

The height has been determined during the months of December to March. This is the period when the amount of snow on the top is likely to be least as the north-west wind is in its full stride. There is heavy precipitation of snow during the monsoon months— June to September—and, although there is no observational evidence available regarding the change of snow fall at the summit, it is likely to be well over 10 feet.

It might be of interest to record here that Makalu which rises from the main snowy range at a distance of 12 miles to the east of Mount Everest has also been re-observed for height. From the Darjeeling hills, this peak dominates the landscape rather than Mount Everest because it is about 12 miles nearer.

It is supposed to be the fifth highest in the world and has been very much in the news lately, as an American Expedition made a bid to conquer it in 1954 for the first time but had to turn back due to bad weather and difficult terrain.

Makalu was observed in 1849-50 from six low-lying stations in the plains, at distances of about 110 miles from it. Like Mount Everest, its height was also computed with a faulty value of the coefficient of refraction and without proper considerations of datum and deflection of the plumb-line and the value adopted was 27,790 feet. In 1952-53, observations were taken to this peak from five stations at distances varying from 35 to 80 miles. The value resulting from these observations after taking due count of the geoid Makalu is 27,824 feet. This is the value which will be adopted for the future.

It might be noted that although the present observations enable the height of Mount Everest to be determined with a high degree of precision, they do not contribute to the question of the uplift of the Himalayas. The question of the amount of erosion at the top of such high hills and the secondary rise to achieve isostasy must still remain a matter of speculation. Although the rock summit is subject to violent seasonal winds, it is never bare of snow and the erosion is not likely to be considerable.

Summary.—The newly determined height of Mount Everest is 29,028 feet. It is but timely that the challenge of its height determination should have been met shortly after its actual conquest. This is the first time that the height of an important inaccessible peak has been determined by a rigorous technique involving a relatively complicated nexus of facts and ideas. Geodetic observations had to be carried close to the peak to get quantitative figures for the distortion of the mean sea-level and the tilt of the vertical produced by the colossus.

The new determination stands in a class by itself and its close agreement with the older value does not signify that the latter was well determined. It is really due to the fact that like is not being compared with like. Judged by modern standards, the earlier deduction of the height of Mount Everest was vague in several respects, and was burdened with large errors on account of neglect or incomplete consideration of certain physical factors. It so happened that by chance the various individual errors, although large, have tended to cancel each other.

There are several outstanding peaks in the Himalayan range —K2, Kangchenjunga, Nanga Parbat, Dhaulagiri, etc.—which also need treatment similar to that in this paper. Doubt still remains whether K2 or Kangchenjunga should occupy the next place. Their accepted heights are 28,250 feet and 28,146 feet respectively and the difference is well within the errors of older determination. Some recent observations have been taken to Kangchenjunga and preliminary computations show that its adopted height needs increasing by 60 feet or so.

Highly-placed Pundits are still arguing about the height.—Editor.

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