OCT. — MAR. 1858-59.] Report of the Magnetic Survey. 345 



The Southern part of India seems to agree better with our re- 

 sults of calculation. 



The decimation was not found as irregularly altered in any of 

 the places examined, as formerly in Cheerapoonjee ; though the 

 gite rocks in the valley of the Brahmapootra on both sides of 

 the river are identic with the rock of the Khossia and the Gar- 

 row Hills along the left edge of the Brahmapootra valley, vary 

 different from the geological situation of the Himalayas along the 

 right side of the valley. Some of these rocks in the valley contain, 

 as well as the Northern parts of the Khossia Hills, a very great 

 amount of magnetic iron (in the rocks near Doobree Colonel Han- 

 nay recently has found it particularly predominant) ; but the ac- 

 tion on the . * * is confined to the place itself, and becomes at 

 a very small distance untraceable. 



The declination in the territory examined was East, being great- 

 est at Koolna and decreasing East and West of it. In Assam, as 

 well as in Meerut, a small increase is caused by the difference in 

 latitude. In Nurigoon, as in the Himalayas in general, the decli- 

 nation is decidedly greater than the difference of latitude would 

 make us expect.* 



A. — The declination was found in the valley of the Brahmapoo- 

 tra and Delta of the Ganges— 



© 



At Debrooghur N. 2 8 E. 



„ Tezpore N. 1 59 E. 



„ Oodulgoorie, N. 2 5 E. 



„ Nurigoon (Bhootan,) N. 4 5 E. 



„ Gowahatty, N. 1 41 E. 



„ Koolna, N. 2 55 E. 



„ Calcutta, N. 2 24 E. 



B. — In the plains of Hindoostan — 



At Benares, N. 1 27 E. 



„ Lucknow, N. 1 12 E. 



* Compare the observations of my brothers in Gurhwal and Kumaon 

 and my observations in Sikhim, Report III. page 6 and Report VI 



