264 Narrikal or Cochin Mud Bank. [No. 12, new series. 



The Mud Bank at Narrikal, near Cochin ;^its composition, as 

 exhibited by the Microscope. By Lieut. J. Mitchell, 



In the month of September last a small quantity, about half a 

 cubic inch, of a dark brown earth was sent to me for examination 

 with the microscope. It was said to be a portion of the great 

 Mud Bank at Narrikal on the Western Coast, the existence of 

 which had lately been brought to the notice of Government by 

 Captain John Castor, Master Attendant at Cochin, and of which a 

 notice appeared in the Madras Times of the 13th August, 1861. 



As this report may have escaped the notice of some of the read- 

 ers of the Madras Journal of Literature and Science, I may say, 

 briefly, that Captain Castor reports the existence of an extensive 

 mud flat, which, commencing about half a mile south of the village 

 of Narrikal extends to the north for about four miles. Within 

 this space, in the height of the S. W. Monsoon, he found the sea 

 without a ripple ! But the greatest stillness of the sea, and the 

 total absence of surf from the beach prevailed between a village 

 named Nairambolum and Narrikal, a distance of about one and a 

 half miles : — at this point Captain Castor was always able to 

 embark from the beach in a small canoe. 



The mud appeared to be exceedingly soft and permitted a 7 lb. 

 lead to penetrate it to the depth of three feet in some parts where 

 there was a super-stratum of from six to ten feet of water, and a 

 bamboo penetrated six feet where there was a depth of six feet of 

 water. Beyond the depth of sixteen feet, the bottom attains 

 greater consistence and appears good holding ground. Three miles 

 and a half from the shore the depth was five and a half fathoms 

 and gradually shoaled towards the shore. We are left to con- 

 clude that the bank extends to that distance from the shore, but 

 this is not distinctly stated in the published account. 



The small quantity sent to me was damp, and appeared very 

 firm and tenacious ; it had however been somewhat compressed 

 by the waterproof wrapper in which it was packed. To ascertain 

 if it contained any minute shells a portion was placed in water, 

 but it did not break up readily, and as I wished to avoid any vio- 



