NATURE 



38^ 



THURSDAY, JULY 17, 1919. 



THE FIGURE OF THE EARTH. 



The Earth's Axes and Triangulation. By J. de 

 Graaff Hunter. (Survey of India Professional 

 Paper, No. 16.} Pp. viii + 219 + vi charts. 

 (Published by order of the Government of 

 India. Dehra Dun : Printed at the Office of the 

 Trigonometrical Survey, 1918.) Price 4 rupees 

 or ss. 4^. 

 'T^HE Survey Department of India has long 

 •*' been labouring under a disadvantage which 

 attaches to pioneers in that the fundamental con- 

 stants employed as the bases of its computations, 

 and upon the accuracy of which its final results 

 depend, are now, and have been for a long time 

 past, known to be in substantial error. The axes 

 of the earth hitherto used are those derived from 

 Everest's early work, and in view of the enor- 

 mous amount of geodetic data accumulated since 

 they were formulated, their values naturally re- 

 quire considerable correction in order to fit in 

 with more recent knowledge. Furthermore, owing 

 to the magnitude of the local attraction at Kalian- 

 pur, the point taken as the origin of the co- 

 ordinates of the survey, the absolute position of 

 this origin, and hence of every other point de- 

 duced from it, requires a further correction on 

 this account. This correction in the case of 

 longitudes is a constant quantity of the same 

 magnitude at every point, and in the case of lati- 

 tudes a varying quantity, depending, first, upon 

 the absolute change in the assumed latitude of 

 the origin, and, secondly, upon the changed dis- 

 tance between origin and point due to the 

 changed spheroid. 



To recompute the whole triangulation with the 

 new origin and new axes would have been a piece 

 of numerical work of altogether prohibitive mag- 

 nitude, and the primary object of Mr. Hunter's 

 research was to derive a formula for ascertaining 

 the necessary corrections without repeating the 

 whole calculation. This is not quite such an 

 elementary problem as it appears. It might pos- 

 sibly be thought that it would be easy to compute 

 the correction at a number of symmetrically situ- 

 ated points, say the intersections of each degree 

 of latitude and longitude, and thence to derive the 

 correction at any other point by interpolation. 

 This, however, cannot be done in any simple and 

 direct way. To derive the proper value of the 

 correction, the "route " along which the position 

 of the point was determined has to be considered, 

 and if, for example, assuming the position of the 

 origin as 0°, o", we thence determine the cor- 

 rection at the point 1°, i", the value will be dif- 

 ferent according as we proceed along the parallel 

 from 0°, 0°, to 0°, i", and thence' along the 

 meridian to 1°, i", or conversely along the meri- 

 dian to 1°, 0°, and thence along the parallel to 

 1°, 1°. This discrepancy arises from the fact 

 that the original observations were "adjusted" — 

 i.e. constrained to fit a particular spheroid — and 

 NO. 2594^ VOL. 103] 



will consequently not fit a different spheroid with- 

 out distortion. There must therefore always 

 remain a degree of uncertainty in the computed 

 corrections, and in the final results it is claimed 

 by Mr. Hunter, apparently with full justification, 

 that these residual errors are of magnitudes such 

 as to be negligible in the most precise geodetic 

 survey. 



The whole question of the adjustment of the 

 errors of a triangulation is fully discussed, and 

 a new method of considerable practical import- 

 ance set forth. The volume embodies the 

 results of a most laborious research, and reflects 

 great credit upon the author and upon the Survey 

 of India. A perusal of it brings home, however, 

 with great force a question much to the fore 

 lately upon which a definite solution appears at 

 length to be in sight, viz. the imperative necessity 

 of establishing a geodetic institute in this 

 country. Many of the problems opened up in this 

 volume are applicable to geodetic surveys 

 wherever they may be undertaken, and it is 

 scarcely an ideal state of affairs that the great 

 responsibility for laying down new methods, and 

 for all practical purposes deciding upon their 

 validity, should rest on the shoulders of one survey 

 department, often, moreover, on those of one man. 

 These general questions should be fully investi- 

 gated by all concerned who are in a position to 

 help, and an institute which will co-ordinate the 

 higher survey work of the whole British Empire 

 will be in a position to assist individual survey 

 departments in all questions of general and funda- 

 mental importance to the science of geodesy. 



E. H. H. 



PLANT PHYSIOLOGY. 

 Life Movements in Plants. By Sir J. C. Bose. 

 (Transactions of the Bose Research Insti- 

 tute, Calcutta. Vol. i., parts i and 2, 1918.) 

 Pp. xxiv-i-251-f-xv. (Calcutta: Bengal Gov- 

 ernment Press, 1918. Published by the Bose 

 Research Institute, Calcutta.) 

 TN addition to a series of scientific papers, the 

 -L volume before us contains administrative 

 details of the Research Institute and an inaugural 

 address delivered by Sir J. C. Bose on Novem- 

 ber 30, 1917, when the institute was opened. 



India is to be congratulated upon the foundation 

 and generous endowment of an institute of this 

 character, which is intended to include depart- 

 ments for physics, plant physiology, animal physi- 

 ology, and psycho-physics, as weU as their 

 applications to agriculture and medicine. 



The address outlines the events leading up to 

 the organisation of the institute. It is pointed 

 out that the two ideals before the countr>- are 

 complementary and not antagonistic. " There is 

 first the individualistic ideal of winning success in 

 all affairs, of securing material efficiency and of 

 satisfaction of personal ambition. These are neces- 

 sary, but by themselves cannot secure the life of a 

 nation. . . . The weakling who has refused 

 the conflict, having acquired nothing, has nothing 



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