70 Papers connected with the construction [No. 31 



No. 3. — On the Currents, fyc. 



My Dear Captain Jenkins, 



I now sit down to inform you of the few particulars regarding the run 

 of the sea and set of the current in the Madras roads, &c. which has 

 come under my notice, although I much fear that my observations have 

 been too loosely made and too over scanty, to be of much service to you. 

 In t^e first place with regard to, 



1st. The distance from shore of the outer surf— From a careful measure- 

 ment in the months of October, November, and December 1838, it ap- 

 peared that on occasions,-^ such as it would be considered dangerous to 

 permit a boat to go off from the beach, the surf extended to a distance of 

 from 450 to 500 feet from the shore, but that, during a smart gale on the 

 6th December the surf extended to or beyond a buoy, which was 828 feet 

 from the shore, but the confusion was such, as to render the distinction 

 between breakers, (such as occur at sea) and the surf, very difficult. In 

 the next place, 



2d. The velocity of the current, was found to vary with the force of 

 the wind and at its maximum, reached to 3 or 3| miles per hour. 



3d. The run of the sea during a monsoon day, such as would be con- 

 sidered dangerous for boats passing through the surf, was found by means 

 of an iron buoy, (which was anchored at 828 feet from the shore) to be 

 five feet, and during a smart gale on the 6th December it was estimated 

 to be nearly double of this, but the want of adequate means on that 

 emergency, prevents my speaking with more precision. 



4th. No observations were made to discover the permanency of the 

 soil, but at 828 feet from the shore, the depth of water was then found 

 to be 18 feet, and at 300 feet from the shore, at which I drove a pile, the 

 distance was once measured twenty feet, and afterwards somewhat more, 

 i. e. between 20 and 20| feet, but beyond this rough sort of 'measurement 

 nothing was attempted, by reason of the pile, (which was intended for a 

 measurement of the tides) being washed a^ * 



5th. The tides in the Madras roads, at a maximum do not exceed 

 3i feet. 



6th. The pile above alluded to, was composed of two buoys of Autcha 

 wood, held together by two iron hoops, that was sunk or rather driven to 

 a depth of five feet by means of a hand jumper, moved by five or six 



