465 HYDROGRAPHIC MANUAL PaGE 394 



fully. Every precaution should be taken to prevent the wheel from jamming in its 

 yoke, as this will frequently result in the wheel being scored by the wire. 



Sheaves with worm gears develop side play in the yoke when worn. This may cause 

 an error of as much as 1 fathom in the dial reading. Therefore, when special accuracy 

 is required, as in comparative soundings, a fairly new and carefully calibrated sheave 

 should be used. Should it be necessary to use a sheave with side play, the wheel should 

 be held against one arm of the yoke wheti setting the pointer, and against the same 

 arm when reading the depth. 



In the counter-type of sheave there is no worm gear, so there should be no error 

 due to side play. 



465. Sounding Wire 



Two types of sounding wire — stranded and piano — are ordinarily used for wire 

 soundings. Stranded wire should be used in depths less than 300 fathoms; piano wire 

 should be used in greater depths. For the use of wire with sounding machines, see 

 3422 and 463. 



4651. Stranded Sounding Wire 



Stranded sounding wu^e is composed of seven tightly twisted strands of double- 

 galvanized No. 24 B.W.G. gage wire, and has a breaking strength of not less than 500 

 pounds. It is furnished in 300-fathom lengths, packed with powdered lime in sealed 

 cans. The diameter of stranded sounding wire is 0.065 inch. 



4652. Piano Wire 



Piano sounding wire is single No. 21 B. and S. gage steel wire. It is furnished in 

 2,000-fathom lengths, packed with powdered lime in sealed cans. Its diameter is 

 0.0285 inch. Although it has a breaking strength of approximately 190 pounds, it 

 should not be subjected to a tension greater than 100 pounds when reeling in. 



The lead should not be attached at the end of piano wire for taking soundings, 

 because the wire is apt to kinl^ when the lead strikes the bottom and to part when reeled 

 in. To avoid this a 25-fathom length of stranded wire or a few fathoms of small 

 Manila line should be inserted between the end of the piano wire and the lead. If a 

 sounding machine with piano wire is used for taking serial temperatures, a 150-fathom 

 length of stranded wire should be inserted between the end of the piano wire and the 

 lead, because most such observations are taken in depths less than 150 fathoms and 

 there is less risk of the stranded wire parting. 



4653. Splicing Stranded Wire 



Stranded sounding wire is seldom used in depths exceeding 300 fathoms, and new 

 wire is furnished in such lengths. Ordinarily it is not economic to splice it, except 

 where it must be used for deeper soundings, or when there is a shortage of wire. 



Where it becomes necessary to splice stranded wire, a regular long wire splice 

 should be made, with the wires ending at varying distances apart throughout the length 

 of the splice. The ends should be tucked and the splice seized with fine copper wire at 

 both ends and one or two places in* the middle. The whole should be cleaned with 

 muriatic (hydrochloric) acid and washed with solder. The solder coating must be 

 quite thin to avoid making the splice too stiff. 



