250 



From the com- 

 mon method 

 of taking 

 soundings ma- 

 ny ships lost. 



Causes of its 

 uiaccuracics. 



New method. 



Soundings ta- 

 ken hi 30 fa- 

 thoms without 



heaTUig to. 



SEA LOG AStD sounding MACHINE. 



vera! Other ships, supplied with the same log, which had kept 

 tolerably well together during the whole voyage, and it had 

 been found (which is more than probable) that all their 

 reckonings corresponded with his; the difference between 

 the true distance, and the distance given by the log, might 

 with the greatest propriety be ascribed to the operation of 

 currents; the existence of which would consequently be 

 discovered, as far as related to those seas. 



The importance of obtaining true soundings at sea must 

 be admitted by every seaman ; and it is rather singular, that 

 no other method than the common lead has hitherto been 

 brought into use; as its imperfections are very generally ac- 

 knowledged. 



Many vessels have been lost, by depending upon the 

 soundings taken in the usual way. The difficulty of ob- 

 taining the true perpendicular, and the uncertainty as to the 

 exact moment when the lead strikes the bottom, upon which 

 the accuracy of the result depends, must always prevent the 

 possibility of obtaining the true depth, while the ship has 

 any considerable way upon her. Indeed, it has been acknow- 

 ledged by experienced seamen, during some experiments, 

 made at various times, in the river Mersey, that they could 

 not depend upon the common lead, when going five or six 

 knots in the hour, in ten or twelve fathoms of water. When 

 the depth is considerable, the vessel must be hove to, which 

 is an operation attended with great loss of time, and some- 

 times considerable injury to the sails; and during a chase, 

 this inconvenience must be particularly felt. 



Massey's sounding machine is as great an improvement 

 upon the common lead, as his patent log is upon the common 

 log. A rotator on the same principle as that to the log re- 

 gisters the perpendicular descent of the lead, without any 

 respect to the length of line paid out, which, in the usual me- 

 thod of taking soundings, is the chief guide to the mariner 

 in judging of the perpendicular depth, and is apt to deceive 

 him much.. 



True soundings may be taken with this machine in thirty 

 fathoms water, without the trouble of heaving the vessel to, 

 although she may be going at the rate of six miles in the 

 hour. True soundings may also thu» be obtained in very 



deep 



