254 



The rotator 

 ttoes not im- 

 pede its des- 



as shown by 

 expei'mieiits. 



SKA LOG AND SOUNDING 3IACHINE# 



tical)ility of its obtaining soundings, in any depth, and no 

 reasonable doubt of their conectnesi> when obtained. 



From the construction of this machine, it might be ima- 

 gined, that the rotator would impede its motion through the 

 water, and that it could not descend so rapidly as the com- 

 mon lead ; but during repeated trials, in thirteen fathoms 

 water, in which the rotator was frequently detached, and the 

 lead suffered to descend alone, there was no difference per- 

 ceptible in the time of their descent, though an excellent 

 quarter-second stop watch was used during the experiment, 

 to detect any change. The following table shows how 

 very uniformly the times of descent corresponded with 

 the depths in fathoms, during a series of trials made on 

 the river Mersey, with the patent lead, weighing fourteen 

 pounds. 



The manner of conducting these experiments was such as, 

 is deserving of perfect reliance. Two pilots, of well-known 

 ability and experience, were employed: one threw the lead, 

 and the other, the moment he found, by the slackening of 

 |he rope, that the weight had arrived at the bottom, cried. 

 * stop,' to a third person who held the watch. 



Time of descent. Fathoms 

 i seconds 

 qL 



3 

 5 



5| 

 6 



7 



-z 

 3 



4 



8 



8f 

 10 

 10 



llf 



Time of descent. Fathoms. 

 71 seconds 11| 

 lU 



n 



71 



-ik 



7i 



8 



81 



6 



12 



12i 



13 



13i 



10 



Taken when under sail, at upwards of five knots in the 

 hour. 



Several captains and masters in the navy have made trial 

 of the log and sounding machine, and given very favourable 

 reports of their performance. Of these the two following 

 may be selected as specimens. 



Sun 



