558 



Report on the Magnetic Survey. 



[No. 6. 



A similar result has been found by ray brothers for the parts of 

 corresponding latitude in the Norths West Provinces and in Central 

 India. 



The Southern part of India seems to agree better with the results 

 of calculation. 



The Declination. 



Tfie declination was not found to alter so irregularly in any of 

 the places examined, as we formerly found to be the case at Cherra* 

 punji, though the granite rocks in the valley of the Brahmaputra on 

 both sides of the river are identical with the rocks of the Khosia 

 and the Garrow Hills along the left edge of the Brahmaputra valley, 

 and the geological situation of the Himalayas along the right side 

 of the valley is very different, Some of these rocks in the valley 

 contain, as well as in the Northern parts of the Khosia Hills, a 

 very great amount of magnetic iron (in the rocks near Doobree, 

 Colonel Hannay recently has found it particularly predominant) * 

 but the action on the needle is confined to the place itself, and 

 becomes at a very small distance untraceable. 



The declination in the territory examined was East, being greatest 

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

 at Meerut, a small increase is caused by the difference in latitude. In 

 Nurigoon, as in the Himalayas in general, the declination is decidedly 

 greater than the difference of latitude would lead us to expect. 



A. — In the valley of the Brahmaputra and Delta of the Ganges, 

 the declination was found to be — 



At Debrooghur, 



.. 5. 2 Q 



8' 



E. 



„ Tezpore, 



.. N. 1 



59 



E. 



„ Oodulgoorie, 



.. N. 2 



5 



E. 



„ Nurigoon (Bhootan,) 



.. N. 4 



5 



E. 



„ Gowhatty, 



. N. 1 



41 



E. 



„ Koolna, 



,. N. 2 



55 



E. 



„ Calcutta, 



.. N. 2 



24 



E. 



,— In the plains of Hindoostan — . 









At Benares, 



.. N. 1 



27 



E. 



„ Lucknow, 



.. N. I 



12 



E. 



„ Agra, .. 



.. N. 1 



14 



E. 



„ Meerut, 



.. N. 1 



28 



E. 



