July 26, 1906] 



NA TURE 



301 



break, and a full discussion of quarantine regulations 

 of various authorities. 



For the administrator and sanitarian in yellow- 

 fever zones the report is indispensable. For permis- 

 sion to reproduce the above two plates we are indebted 

 10 the courtesy of the Coloni.-il OHu-e. 



J. W. W. Stephens. 



SCIENTIFIC WORK DF THE SURVEY OF 

 INDIA.' 



Ii- .iiiv .ipciUigy were needed for the mainttnance of 

 the scientiiic work of the Indian survey it will 

 be found in No. ^) of the series of professional papers 

 of that department, which has been especially prepared 

 fur the use of the Survey Committee of 1905 by 

 Lieut. -Colonel S. G. Burrard, R.E., F.R.S., the 

 Superintendent of Trigonometrical .Surveys in India. 

 That committee was appointed for the purpose of 

 examining into the e.xisting system of the Indian 

 -Survey Department with the view of rendering it more 

 efficient as a topographical institution, having regard 

 to the increasing demand for more accurate military 

 mapping in India, and the necessity for more perfect 

 revision of those maps which are gradually failing 

 out of date with the advance of public works de- 

 velopments. India is an unscientific country. The 

 scientific members of the .Anglo-Indian community 

 would hardly fill a first-class carriage on any railway 

 line, and they exist only as paid servants of the 

 Government, living in constant fear of " reduction " 

 when any financial crisis occurs. They have to justify 

 their existence from time to time, and Colonel 

 Burrard is to be congratulated on the very .effective 

 justification which he has given to the public for 

 the maintenance of the scientific branches of his 

 own department. It is all the more valuable for 

 the reasons that the booklet which contains his 

 opinions is written in clear and simple language, 

 intelligible even to the most unscientific reader, and 

 that it appeals directly to a fai wider circle of men of 

 science than can be found in any one department. 

 The various sections of the scientific work which 

 Colonel Burrard superintends are principal triangula- 

 tion, levelling, astronomical, pendulum, magnetic and 

 tidal observations, and solar photography. He deals 

 with them all in turn concisely, showing their relative 

 interdependence and their practical utility. 



No distinction is drawn by Colonel Burrard between 

 scientific and practical work. He maintains rightly 

 that their relations are constant. " The primary 

 object of a national survey is the making of maps, 

 and all operations are subordinated to that end. It 

 is for topographical purposes that a national survey 

 measures its allotted portion of the earth's surface. 

 If, however, these measurements be combined wit'.; 

 astronomical determinations, the size and shape of 

 the earth can be deduced, and a knowledge of this 

 size and shape is essential to astronomers, geo- 

 graphers, geologists and meteorologists, ail of whom 

 look to survevs for information." Here, then, is the 

 principle of geodetic triangulation enunciated, and 

 the wholesome doctrine recalled to mind that it is 

 the measurement of " areas," and not " arcs," which 

 will be found most useful for the geodesist as for 

 the practical topographer. The connection between 



' Surveyor India, Professional Papers, Serial No. 9, 1905 :— An Account 

 of the Scientific Work of the Survey of India, and a Comparison of its 

 Progress with that of Foreign Surveys prepared for use of the Survey 

 Committee, IQ05. A pamphlet by Lieut. -Col. S. G. Burrard, R.E., F.R.S. 

 (Calcutta : Office of the Superintendent of Government Printing, 1906.) 

 Price IS. 6rf. 



the principal triangulation and secondary methods is 

 well illustrated, and incidentally we arc shown the 

 relative degrees of accuracy of the triangulations of 

 different countries. Taking the ratio between pre- 

 cision and length of the triangulation of Great Britain 

 as a unit, we find that ratio to be o-O in Russia and 

 0.7 in India, the only two countries which can claim 

 a superior degree of accuracy, while in France and 

 Prussia it rises to 2-5 and 2-6 respectively, and we 

 are told that -South -Africa and the United States are 

 equal in precision to France and Prussia. This is 

 something of a surprise, for we were always under 

 the impression that the triangulations of these two 

 last countries was of a very high degree of accuracy 

 as compared with that of older systems. 



Colonel Burrard proceeds to show that we have 

 by no means arrived at an ideally accurate frame- 

 work for the basis of our mapping even yet. Accurate 

 as the process of measurement may be, inaccuracies 

 in the data for reducing observations introduce very 

 considerable and very practical errors. The deflection 

 of the plumb line, the deformation of the earth's 

 figure (which has upset the original calculations of 

 the earth's size, giving it a diameter which is two 

 miles too short), and other physical causes of initi.ii 

 error have this effect, amongst others, viz., that we 

 are 1000 feet too far north with our position of 

 Peshawar in northern India, and two and three- 

 quarter miles too far east with our position of the 

 Salween River in Burma. This is of little conse- 

 quence until we come to an international junction 

 with other survevs. It has already had a certain 

 effect in the junction of the geographical surveys 

 of -Afghanistan and Russia, which (after making due 

 allowance for these errors) was fairly satisfactory. 

 When, however, a connection between the principal 

 triangulations of these two countries is effected, it 

 may become necessarv to revise our Indian data ; but, 

 as Colonel Burrard wisely points out, unless we are 

 to continue systematical'lv to combine with other 

 countries (nota'blv South -Africa and -America) in the 

 elucidation of those scientific problems which form 

 the basis of the world's mapping, we shall never 

 reach the possibility of a final revision which will 

 place our international boundary pillars in the same 

 terms as regards their position on the earth's 

 surface- 

 No practical surveyor will quarrel with Colonel 

 Burrard's conclusions, or be disposed to criticise his 

 plea for extending the principal triangulation of India 

 far enough to cover the Indian borderlands, where 

 it is of almost paramount importance that we should 

 possess a substantiallv accurate basis for topography. 

 -After all, this preliminary work of the most scientific 

 class only adds 10 per cent- to the final cost of the 

 survey. 



The interdependence of astronomical, pendulum (tor 

 .nvestigating the eccentricities of the force of gravity), 

 and levelling operations is duly emphasised, and in 

 connection with the latter some interesting details are 

 given regarding the probable heights of the highest 

 peaks in the Himalavas. These details have already 

 been referred to in the pages of Nature. Investiga- 

 tions into magnetic phenomena and solar physics 

 speak for themselves. They cost little, and add 

 greatly to the sum of our scientific knowledge of 

 the da'ta surrounding certain most obscure and elusive 

 natural forces. , 



As a unit in the series of professional papers ot 

 the Indian survev, this is perhaps the most im- 

 portant that has vet appeared, and it is one whicli 

 appeals to a world-wide community of practical 

 survevors. 



NO. 1917, VOL. 74] 



