THE MOST CURIOUS CRAFT AFLOAT 



235 



8 , i I ? » ' « • ■ . I f , 



# 



^ ■> 



THE "crescent" : ADEN, ARABIA 



present appliances for controlling and 

 checking a ship's course and her position. 



When the solar azimuth attachment 

 was devised, with the aid of which the 

 surveyor was enabled to run true lines 

 instead of magnetic ones, some believed 

 that the compass needle for surveying 

 was doomed. But the sun and stars are 

 not always visible, whereas the earth's 

 magnetism is ever in evidence, and the 

 temptation to resort to the needle could 

 not be resisted. Then again, for running 

 a line through dense forests, or for lay- 

 ing a trial course between two non- 

 intervisible objects, the transit instru- 

 ment presents difficulties ; the line must 

 be cut open, trees must be felled to per- 

 mit the surveyor to sight ahead and 

 plant his stakes. The compass surveyor, 

 however, may pick his way unaided 

 through the thickly-wooded jungle, and, 

 while his line may not be as true as that 

 of the transit-man, it frequently suffices 

 for the purposes, if traced with some 

 care. 



So it is with this recentlv in\ented 



Anschuetz-Kaempfe gyroscope compass 

 now being installed on German war 

 vessels, and said to be used with success 

 by them. Let those use it who can afford 

 to do so, and who, above all, have the time 

 and facilities for studying it and check- 

 ing its indications thoroughly. It is safe 

 to say that, even on vessels thus equipped, 

 the magnetic compass will not be wholly 

 discarded. In fact, it may turn out that 

 the new instrument will be most service- 

 able if used as a control or check upon 

 the mariner's compass. For ordinary ves- 

 sels the expensiveness, cumbersomeness, 

 and frequent necessary control by sun or 

 stellar observations of the new instru- 

 ment will be prohibitive. It should be 

 stated that if the gyroscope is set whirl- 

 ing with the axis pointed due north at 

 the port of departure, and a due east 

 course is set, for example, the axis will 

 not continue to .point due north — this be- 

 cause of the convcrgency of the merid- 

 ians. Hence this instrument will also 

 have its errors or deviations, not due this 

 time to the iron in the ship, but siniply 



