NATURE 



217 



THURSDAY, JANUARY 7, 1892. 



INDIAN METEOROLOGY. 



Report on the Meteorology of Itidia in 1889. By John 

 Eliot, M.A., Meteorological Reporter to the Govern- 

 ment of India. Fifteenth Year. (Calcutta : Govern- 

 ment Press, 1 891.) 



Reports on tJie Administration of the Meteorological 

 Department of the Government of India, 1 885-1891. 

 (Calcutta, Government Press.) 



MR. ELIOT'S Report on the meteorology of India in 

 1889 is much more than a mere mass of statistics, 

 the raw material for future utilization — more than a retro- 

 spective summary of the weather phases and incidents of 

 the year, which may or may not be turned to future 

 accounf by someone gifted with that scientific imagination 

 that alone can infuse life and meaning into the dry bones 

 of our voluminous weather records. These, indeed, it 

 gives with the usual fulness — not in the fragmentary fashion 

 of a gallery of cabinet studies, but with something of the 

 continuity and breadth of a diorama ; and over and above 

 these, it deals with many topics of general interest, which 

 are real and valuable contributions to the body of the 

 science, and on which the remarkably favourable con- 

 ditions of India — a great tropical country dotted over with 

 a well-organized system of observatories under the direc- 

 tion of a competent physicist — are peculiarly fitted to 

 throw light. 



Foremost among these, stands the question of the 

 incident solar heat, which is at once the most important, 

 and at the same time one of which we have the least 

 exact knowledge. To this question more attention has 

 been given by the Meteorological Department of India 

 than by that of any other country ; and if we must regret- 

 fully admit that the results bear but a small proportion to 

 the labour expended on obtaining them, the experience 

 gained of the difficulties attending the inquiry is not 

 without its value. 



Some years ago it was thought that the position of Leh, 

 in the dry climate of Western Tibet, 11,500 feet above 

 the sea, offered peculiar facilities for obtaining trustworthy 

 measurements of the solar heat ; and in 1882, Sergeant 

 Rowland, a highly intelligent officer of the Royal 

 Engineers, was selected in England, and after a year's 

 careful training at Roorkee in the use of Balfour Stewart's 

 actinometer, under the personal superintendence of Mr. 

 J. B. N. Hennessey, was despatched to Leh, together 

 with a European assistant, who had been equally trained 

 to the work. They were furnished with elaborate in- 

 structions, drawn up by Mr. Hennessey, which contem- 

 plated observations of two classes. On all clear days 

 observations were to be taken at noon, and also once in 

 the morning and once in the afternoon, with the sun at 

 certain definite altitudes ; and on certain selected days 

 (from one to six in each month) similar observations were 

 to be taken at short intervals in succession during so many 

 hours as the altitude of the sun should exceed a certain 

 assigned minimum. The observers remained at Leh 

 nearly two years, and undoubtedly accomplished all that 

 NO. I 158, VOL. 45] 



it was possible to do under the circumstances of the 

 climate ; but this proved to be little, if at all, superior 

 to that which might have been obtained at some of the 

 easily accessible stations of the outer Himalaya, and the 

 total outcome of the twenty-three months' work was seven 

 complete series recorded at short intervals, and sixty of 

 of the tri-daily measurements, together with fifteen in- 

 complete series of the former and ninety-five of the latter, 

 which had been more or less interrupted by the obscura- 

 tion of the sky. Moreover, the instrument by no means 

 answered to the expectations of the inventor. Its chief 

 apparent recommendation was the simplicity of its 

 manipulation ; but it was found to require careful at- 

 tention to a number of minute and elaborate details in 

 order to insure that the observations should be com- 

 parable inter se, and although the registers obtained 

 were examined and discussed by Prof. Balfour Stewart 

 shortly before his death, they were not found to lead to 

 any definite conclusions of such importance as to justify 

 their publication. 



Notwithstanding the discouraging results of this ex- 

 pedition, the investigation has not been abandoned. After 

 Sergeant Rowland's return from Leh, actinometric observa- 

 tions were carried on during the clear season at Mussoorie, 

 and lately under Mr. Eliot's supervision at Simla, and the 

 late Prof. Hill was engaged in the examination of some 

 of this later work, when it was brought to a standstill by 

 his premature death. It is, we believe, now contemplated 

 to make actinometric and other physical observations a 

 part of the future work of the Madras Observatory, and 

 with that view, and also in the interests of astronomy, to 

 transfer the Observatory to some suitable site on one 

 of the lofty hill-groups of Southern India, a step long since 

 recommended on general grounds. 



From the first establishment of the Indian Meteoro- 

 logical Department, the sun-thermometer in vacuo has 

 formed part of the equipment of every observatory ; and 

 every instrument, before being issued, has been subjected 

 to a prolonged comparison with an arbitrary standard, in 

 order to evaluate the mean effect of those irregularities 

 which affect the readings of all instruments of this class, 

 and in many cases amount to differences of 15° and more 

 between thermometers constructed by the best makers. 

 This precaution, however, has proved inadequate. It has 

 long been known that the average readings of many of 

 these instruments undergo a considerable decline in the 

 course of a few years, and that in many cases the glass of 

 the inclosing jacket becomes gradually opaque. During 

 the year 1889, twenty-four observatories were each 

 provided with three carefully compared instruments of 

 different ages, and the observers were instructed to take 

 the observations as accurately as possible. Mr. Eliot 

 says :— 



" The results of the three instruments exposed under 

 identical conditions were in the great majority of cases so 

 widely discrepant as to show that the instrument, from 

 defects in its construction, cannot, at least under the con- 

 ditions of its employment in India, be relied upon to give 

 consistent and reliable results." 



The late Prof. Hill subjected these registers to a critical 

 examination, and his conclusions, being based on the 

 results of seventy-two instruments, may be taken as fairly 



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