1856.] 



Report on the Magnetic Survey. 



27 



Then another set of soundings was taken, using a larger boat 

 with an anchor, the position of the places was ascertained by 

 bearings to the light house and the chimney of Major Vetch's house. 

 Light house from Major Vetch : — 



Angular height of the white column, 31' 30" 



metres. 



Lineal height, , 5 16 



Bearing magnetic, N. 22° 5 E. 



Resulting distance, * 563.2 metres. 



The places of the soundings and the depth found are contained 

 in the following table and laid down in the plan of the Section : 





Distance from the shores of the 



Distance from 





main branch of the Brahmaputra. 



the line of 

 the section 

 in metres. 



Depth in 

 metres. 



O d- 



From left shore 



From right shore 



k< 



in metres. 



in metres. 







l 



42.5 C measured 

 65.0 < by a rope 





Below 15 



4.5 



2 



. . 



„ 17.5 



5.8 





( directly. 









3 



90 to 110 



• • 



„ 28. 



9.3 



4 



420 5 



. . 



Above 20.1 



17.1 



5 



450 to 470 





Below 180. 



17.3 



6 





370 to 390 



„ 230 



18.0 



7 



. m 



265 



„ 102.5 



17.8 



8 



. # 



170 to 195 



„ 225.0 



16.5 



9 



. . 



52.5 



„ 111.5 



14.0 



10 



. # 



15.0 



„ 70. 



5.0 



11 



. . 



8.0 



„ 52.5 



1.0 



12 



... 



2.5 



„ 40.0 



0.5 



Note. — No. A in the plan was above the island of Oommanand 

 and a little to the right of it. Depth 12.5 metres. 



No. 4. — Velocity of the water. 

 The following table contains the numbers found for the velocity 

 of the water at different points. The velocity was ascertained, No. 

 A for the surface by an empty pot (ghurrah), No. B for depths of 

 7.5 and 10.0 meters by bamboos loaded below with sacks containing 

 sand and protected against their sinking deeper than their full 

 length by a pot tied to the upper end, a thin and very soft rope, 100 



E 2 



