Intelligence and Miscellaneous Articles. 



465 



Stations. 



Longitude. 



Latitude. 



Date. 



Horizontal 

 force in 

 dynes. 



■ 

 Dip. 



Calcutta .... 

 Jubbulpore . . 

 Allahabad .... 



88° 22 50 



80 00 00 



81 54 12 



22 32 32 



23 10 00 

 25 27 43 



Jan. 1878 

 Dec. 1877 

 Dec. 1877 



0-37158 

 0-3(J667 

 0-35915 



28 59 30 



29 23 30 

 33 18 45 ; 



Dividing the horizontal component by the cosine of the dip, we 

 obtain the total force thus : — 



Calcutta . 0-42482 dyne. 

 Jubbulpore. 0-42084 „ 

 Allahabad . 0-42977 „ 

 There are on record several observations of the dip in Calcutta, 

 which it will be interesting to bring together here. 



The dip appears to have been measured for the first time when 

 the French corvette 'La Chevrette' visited these waters in 1827, 

 by M. de Bios Seville, who found it then to be* 



26° 32' 38". 

 Ten years later, in 1837, on the occasion of the visit of another 

 French corvette, 'La Bonite,' to the Hugli river, the dip was 

 measured at Kalagachia (Diamond Harbour) by the chief Hydro- 

 grapher, who found it to bet 



26° 39' 04", 

 exhibiting a change of only 0° 06' 26" from the result of the 

 earlier measurement. 



The next and most recent measurement was made by the brothers 

 Schlagintweit in March 1856 and in April 1857, in which years it 

 was found to be respectively + 



28° 06' 43" 

 and 28° 22' 56". 

 The same observers found the dip at Jabalpur in December 1855 

 tobe§ 28° 31' 08" 



Their measurements of the horizontal force gave : — 

 0-37386 dyne at Calcutta in March 1856, 

 0-36644 ,', „ in April 1857, 



0*39959 ,, at Jabalpur in December 1855. 

 A very valuable series of observations was made in 1867-68 by 

 the late Captain Basevi, R.E., under the orders of Colonel J. T. 

 Walker, C.B., E.E., Superintendent of the G-. T. Survey (now 

 Surveyor-General of India), at 14 stations, extending from 15° 6' 

 to 30° 20' north latitude || ; but none of them are coincident with 

 the three stations under consideration. 



The values of the dip and horizontal intensity at the limiting 

 stations of the series were as follows : — 

 * Asiatic Researches, vol. xviii. part i. p. 4. 



t Proceedings, Asiatic Society of Bengal, Wednesday, 3rd May, 1837. 

 % 'Observations in India and High Asia,' vol. i. § Loc. cit. 



j| General Report of the Operations of the Great Trigonometrical Survey 

 of India during 1867-68. 



Phil. Mag. S. 5. Vol. 6. No. 39. Dec. 1878. 2 H 



