406 



NATURE 



[August 23, 1883 



In the matter of vertical range we are no less badly off, our 

 loftiest elevation being less than one-fourth of that attainable in 

 some countries. 



Fortunately for us, however, we have a dependency which 

 offers rare facilities for the study, not merely of climate and 

 weather, but of what is acknowledged to be the "highest 

 branch of meteorology," viz. atmospheric physics. ^ 



India has, in fact, been often specially alluded to by leading 

 meteorologists as a golden field for this line of re-earch, and Mr. 

 Blanford has with evident pride ventured to predict that, "given 

 a few earnest and intelligent workers, this country [India] will 

 one day play a part second to none in the advancement of 

 rational meteorology." - 



The characteristics presented by India, and which have been 

 specially noticed by Blanford, Buchan, and others, are (1) its 

 great size— more than fifteen times that of what we are pleased 

 to call Great Britain ; (2) its proximity to the equator ; (3) the 

 seclusion of its area by the Himalaya on the mrth ; and (4) the 

 physiographical contrasts it presents. If anything further were 

 needed to show the desirability of investigating the meteorology 

 of India, it would be the fact noticed by Prof. Eliot in his 

 "Report" for 1877 (p. 48), that while in Europe the changes 

 of weather take place mainly in a horizontal direction, the homo- 

 geneity of those in India over large areas shows that they are 

 rather the result of vertical (expansive and contractive) actions, 

 from which it follows as a necessary corollary that if the dyna- 

 mics of the atmosphere are ever to be solved, we must c unbine 

 the facts obtained from regions of vertical with those from 

 regions of horizontal motion, and, as Eliot says, " the two sets of 

 facts must be regarded, not as opposed to, but as supplementing 

 each other." Some idea of the work that is being done and the 

 area it represents may be gathered from the fact that according 

 to the "Report on the Meteorology of India for 1880" there 

 are now 121 stations in the Indian area (including Ceylon and 

 I'.umah) where meteorological observations are regularly made, 

 together with 385 raingauge stations, representing in all an area 

 of 1,131,000 square miles. 



This work finds an official outlet in the excellent "Annual 

 Reports" published by Blanford, as well as the valuable 

 monographs on the " Meteorology of Bombay," by Mr. Charles 

 Chambers, F.R.S., and those on the *■ Bay of Bengal Cyclones," 

 by Prof. J. Eliot, and it will, we venture to think, be admitted 

 by all who have carefully examined these works that they not 

 only reflect great credit on the ability of the writers, but go 

 some considerable way towards indorsing Mr. Blanford's pre- 

 diction. 



Besides these strictly official works, there are published a 

 series of papers entitled the "Indian Meteorological Memoirs," 

 which are intended, according to the preface by Mr. Blanford, 

 as " a vehicle for the publication of such portions of the work 

 of the officers of the Indian Meteorological Department as do 

 not form part of the regular Annual Reports on the Meteorology 

 of India." 



In the present articles we purpose noticing briefly the first 

 co nplete volume of these. Before doing so, however, we may 

 observe that their quality is uniformly of a remarkably high 

 order. We know of nothing approaching to them in this 

 country in meteorology, except, perhaps, occasional papers in 

 the Transactions and Proceedings of the Royal Society, or a few 

 publications of the Meteorological Council; and we have to go 

 abr >a<l, to the Repertorium of Russia, or the Zeitschrifl of 

 Austria, before we can find papers of equal calibre. This defect 

 is unfortunately more readily explained than remedied. In this 

 country our best men, for reasons which are many of them 

 obvious, ani which we need not dwell upon, devote themselves 

 to aim >st any other science but meteorology. The consequence 

 is that little is done, and that little often indifferently, thus in 

 some measure justifying the scorn which many physicists openly 

 entertain for the science and all its disciples. Before, however, 

 these gentlemen pledge themselves to their verdict, let them 

 look abroad to America, Russia, and India, where more interest 

 is taken in the science, and where the field of operations is 

 vastly more extensive, and the conditions more favourable, and 

 we suspect they will be inclined to modify their views somewhat, 

 and allow that after all this useful and still growing science can 

 n it oily borrow from their laboratories, but repay with interest, 

 and that it offers a more divergent scope than is often imagined 

 fjr discoveries ten ling to throw light on some of the most intri- 

 cue problems of physics. 



1 Vide " Elementary Meteorology," by R. H. Scott, F.R.S., 1883, p. 4. 

 - '' Vade Mecum," p. 3. 



Vol. I. of these "Memoirs" comprises twelve papers, the first 

 of which is dated December 8, 1876, and the last October, 1881, 

 which we will now proceed to examine seriatim. 



Paper I. "The Winds of Calcutta," bv H. F. Blanford, 

 F.R.S. 



This paper represents an analysis of ten years' hourly observa- 

 tions of the wind vane, and four years' anemograms. One of the 

 first things we notice is that while the annual resultant, calculated 

 by Lambert's formula, which takes no account of variation of 

 velocity but assigns an equal value to all observations, is south 

 14° west, that derived from the four years' anemograms, where 

 the true resultants enter, is south iS° east, the difference being 

 caused by the greater frequency and less velocity of west than 

 east winds at Calcutta. Another interesting conclusion dedu- 

 cible from the annual figures is that the velocity of the Bay of 

 Bengal (south-east) branch of the monsoons current is consider- 

 ably less than that of the Bombay, or as it is called Arabian Sea 

 (south-west) hranch of the monsoon. This fact was previously 

 noticed by Mr. Blanford in his paper on the " Winds of Northern 

 India, "' and receives further confirmation from a comparison of 

 wind-velocities at representative stations in the Bombay and 

 Bengal Presidencies in recent reports. Thus in that for 1877 

 Prof. Eliot gives the following comparison of velocities for 

 representative stations in August, on opposite sides of the 

 Peninsula : — 



Prof. Eliot ascribes this defect in velocity of the Bengal 

 branch of the monsoon to the deflection it undergoes by im- 

 pinging upon the Arakan and Himalayan ranges. 



And doubtless this expresses a portion of the truth. It 

 ignores, however (explicitly at least), a circumstance which we 

 think has a good deal to do with the result, viz. the fact that this 

 deflection acts so as to continually rob the current of its easterly 

 component, due to the change of latitude, and which, in conse- 

 quence of its northerly direction, tends to be continually repro- 

 duced. In consequence of this, the current, instead of rebound- 

 ing from the Arakan hills once for all, tends to hug the moun- 

 tains all round the northern borders of Assam, and c msequently 

 loses a good deal of its velocity by the friction thus engendered. 

 The importance of this south-east branch of the monsoon current 

 cannot be over-estimated. It depends evidently for its existence 

 on the presence of the Bay of Bengal, so that, were the latter 

 area land instead of water, the now moist and fertile districts of 

 Assam and Bengal would probably be arid wastes like the deserts 

 of Scinde and Rajputana. 



In discussing the diurnal variation in the direction and velo- 

 city of the wind, Mr. Blanford alludes to Mr. Chambers' dis- 

 covery of the relation between the double diurnal variation in 

 the wind components and the critical points in the diurnal baro- 

 metric tide. 



M. Rykatcheff not long ago, on the basis of the diurnal 

 variation of the east and west components of the wind, laid the 

 foundations of a most ingenious theory of the cause of the diur- 

 nal variation of the barometer. 2 Detailed reference to it here 

 would be out of place, but it may be observed that the fact of the 

 easterly components prevailing at the time of diurnal rise and 

 the westerly at the time of the fall of the barometer, both at 

 Calcutta and Bombay, accords with the daylight conditions at 

 all the stations ci'ed by Rykatcheff, as well as with the view 

 that the air near the surface flows nut from the 10 a.m. wave 

 of high pressure, both in its advance from the east and its retreat 

 towards the west. 



The explanations of the diurnal oscillation of the barometer, 

 propounded by Rykatcheff and Chambers, while they coincide 

 in attributing it to the proximate influence of the analogous 

 diurnal variation in the velocity and direction of the wind, differ 

 from each other essentially in one or two points. Thus Ryka- 

 tcheff leaves the north and south components out of account 

 1 Phil. Trans., vol. clxiv. part ii., pp. 563-653. 



' -'La Marche Diurne du Barometre en Russie et quelques Remarques 

 concernant ce Phenomene en general." Rtp. f&r Met., 1879. 



