32 SUBMAEINE CABLE LAYING AND REPAIRING. 



in the tow line in front of the rotator keeps it sufficiently 

 beneath the surface when going at full speed. The bearing line 

 is used for lifting the chain and preventing the rotator sinking 

 when the ship slows down. This line is rove through an eye 

 on the end of a light spar lashed to the bridge and is suspended 

 from a high point on the foremast. The portion (C) attached 

 directly to the chain in the water is of copper wire, which cuts 

 the water more readily than line and affords a little extra 

 steadiment by its weight. When the ship is rolling heavily 

 the bearing line is slackened so as not to lift the log out of the 

 water. This manner of supporting the log prevents it sinking 

 when the ship slows down, and, being kept always in a hori- 

 zontal position, the log registers correctly at quite slow speeds. 

 This is a great improvement over a log towed from the stern 

 which sinks as soon as the ship slows down and must be hauled 

 in. The advantage is greatly appreciated in short distance 

 soundings as the log always remains out and is ready for work 

 whether the ship slows down, stops, or is manoeuvred about. 

 In Mr. Anthony S. Thomson's Paper, before the G-eographical 

 Congress of 1895, on "Remarks on Ocean Currents," &c., occurs 

 the following paragraph relative to all logs, which is worth 

 giving in full : " Whatever be the kind of patent log used, its 

 indications should be carefully checked from time to time by 

 comparing them with the 'Dutchman's log' at different speeds 

 whenever any current observations are to be made. Empty 

 bottles answer admirably for this purpose when ballasted with 

 a little water. The observer, who stands on the bridge with a 

 stop-watch, requires three assistants, one to throw the bottle 

 ahead of the ship, one to dip a hand-flag as the bottle passes 

 his marks at the stem, and another to do the same thing when 

 the bottle passes his marks at the stern. It is convenient to 

 read the revolution indicator and the bridge log before and 

 after timing the bottle, with an interval of six minutes between 

 the two sets of readings. When a number of such observations 

 are carried out with care, the mean results will give the ship's 

 speed through the water very accurately, and the percentage 

 of error of the log at the given speed is easily ascertained and 

 allowed for." 



It is very important as regards the life of a cable that it 

 should not be laid over a bank or steep submarine peak. Such 



