72 HANDBOOK OF MAGNETIC COMPASS 



(g) Metal doors in wheelhouse. 



■ (A) Chart table drawers. 



{i) Movable gyro repeater. 



(j) Windows and ports. 



(k) Signal pistols racked near compass. 



(l) Sound powered telephones. 



(m) Magnetic wheel or rudder mechanism. 



(n) Knives or ash trays near binnacle. 



(0) Watches, wrist bands, spectacle frames. 

 (p) Hat grommets, belt buckles, metal pencils. 

 (q) Heating of smoke stack, or exhaust pipes, 

 (r) Landing boats. 



2. Some electrical items which cause variable deviations if placed 

 too close to the compass are as follows : 



(a) Electric motors. 



(h) Magnetic controllers. 



(c) Gyro repeaters. ! 



(d) Nonmarried conductors. 



(e) Loud speakers. 



(/) Electric indicators. 



{g) Electric welding. 



{h) Large power circuits. 



(i) Searchlights. 



(j) Electrical control panels or switches. 



(k) Telephone headsets. 



(1) Wind shield wipers. 



(m) Rudder position indicators, solenoid type. 



(n) Minesweeping power circuits. 



(o) Engine room telegraphs. 



(p) Radar equipment. 



(q) Magnetically controlled switches. 



(r) Radio transmitters. 



(s) Radio receivers. 



(t) Voltage regulators. 



105. There is another source of transient deviation trouble known 

 as the Gaussin error. This error results from the tendency of a 

 ship's structures to retain some of their induced magnetic effects for 

 short periods of time. For example, a ship travelling north for 

 several days, especially if pounding in heavy seas, will tend to retain 

 some fore-and-aft magnetism hammered in under these conditions of 

 induction. Although this effect is not too large and generally de- 

 cays within a few hours, it may cause incorrect observations or ad- 



