Page 397 equipment and instruments 466 



heavy oil or hot tallow should be held occasionally against the wire on the reel, while 

 reeling in, for additional protection. 



The sounding machine itself should be protected by a canvas cover when not in use. 



The original cans of wire should not be opened until the wire is needed. When a 

 can is opened, either all of the wire should be put on the sounding machine or the unused 

 remainder should be wrapped in oiled cloths before it is stowed away. 



466. Sounding Leads and Weights 



Sounding leads are weights attached to the leadline, or sounding wire, for the 

 purpose of carrying it to the bottom, so that a vertical measlurement of the water 

 depth can be made. 



The proper weight of lead for use in handlead sounding is given in 462. Weights 

 varying from 14 to 110 pounds are used with sounding wire depending on the depth. 

 In depths from 15 to 100 fathoms a lead weighing 14 to 25 pounds should be used for 

 launch wire sounding. With a ship sounding machine a 35-pound lead should be used 

 for depths to 1,000 fathoms, which is about the maximum depth from which it is 

 practicable to recover the weight without risk of parting the wire. In depths greater 

 than 1,000 fathoms, a detachable, pear-shaped, cast-iron sinker weighing about 65 

 pounds is used with a detaching rod. When this strikes the bottom the sinker is 

 detached and remains on the bottom. The strain on the wire is thus decreased when 

 only the detaching rod is brought back to the surface. 



4661. Sounding Leads 



Sounding leads in the standard weights of 5, 7, 9, 14, 25, 50, and 80 pounds can 

 be requisitioned from Naval Supply Depots, and other weights can be purchased com- 

 mercially. Molds can be made up, if desired, and kept on board for use in makihg leads. 

 Leads should be 1}^ to 2 inches in diameter, the length varying with the weight. There 

 should be a cup-shaped depression in the bottom of a lead to receive tallow, soap, or 

 other arming material used to obtain bottom samples. The upper end of the lead 

 should be shaped like an eye, to which the line or wire is made fast. 



The preferable method of attaching a lead to a leadlifte is to make the leadline with 

 a galvanized thimble at the lower end to which the lead is attached by a shackle. Some 

 leadsmen prefer to use a piece of leather between the lead and line, or the line itself 

 may be passed twice through the eye in the lead, doubled back against the standing 

 part, and seized in several places. Whichever method is used, the lead must be attached 

 to the line when it is marked, and thereafter if the end of the line wears so that a piece 

 of it must be cut off, the line must be re-marked. 



In sounding where the bottom is hard or rocky, the lower end of the lead will soon 

 be flattened and spread out; it must then be hammered or trimmed to its original shape, 

 as a misshapen lead will' sink more slowly. 



4662. Lead for Rocky Bottom 



An effective sounding weight for use where the bottom is hard or rocky is made by 

 filling a section of heavy galvanized iron pipe with molten lead. The pipe should be 

 1 to 2 inches in diameter, depending on the weight desired. For use in attaching the 

 pipe lead to the wire, a U-shaped 5i6-inch rod or the end of a short length of chain should 

 be set in the lead as it cools. A snapper, described in 4761, may be inserted in the 



