92 ' NOTE ON 



netic oxide of iron, and occurred in larger average proportion than in 

 the Brahmapootra, but only in the form of minute spangles, very liable 

 to be carried away during the washing. The gold was found to diminish 

 in quantity, as the localities were nearer to the hills. 



The great Dihong River, flowing from the hills to the Northward 

 yielded gold in considerable quantity, from its junction with the Brahma- 

 pootra to about half way between that stream and the hills. One 

 hundred and fifty maunds (or 5f tons) of gravel yielded 90 grains of 

 gold, equal to 16]- grains per ton ; and if the large fragments of rock, 

 &c., which are removed by hand, be excluded, the yield may be estimated 

 at 22 grains to the ton. This stream is considered by the natives to be 

 the richest in Assam.* 



The apparatus employed in these investigations were a Califomian 

 cradle (" long torn") worked by four men, and which was found to give 

 the largest daily yield per man ; three native troughs, or Doorunis, each 

 worked by three men ; and a Singpho washing dish, worked by one washer 

 and one assistant. 



From these Eeports, it will be evident, that the mode of occurrence of 

 gold in TJpper Assam is similar to that in California, in the Ural, and 

 in Australia, vis., that it is derived from the crystalline rocks in the 

 first instance, but only becomes sufficiently concentrated to render it worth 

 working in the alluvium, after this alluvium has undergone repeated 

 washings in the river current, by being successively cut away, washed, 

 and re-deposited, as the river changes its course. There, as elsewhere, 

 it will be found a fruitless task to attempt and trace the gold to its source, 

 under the impression that the original rock in situ would afford a richer 

 yield than the same rock pulverized and sifted by the action of the river. 

 Even were an auriferous quartz vein discovered, it is more than doubtful 

 (judging from the experience of gold miners every where else), whether 



* This is the great feeder of the Brahmapootra, and supposed to be the continuation of 

 the Teampoo of Thibet, which drains the Northern slope of the Eastern Himalaya. 



