SANDY SHORES 79 



wire is indeed a surveyor's nightmare. This apparatus was now 

 used to measure the distance from the anchored beacon to the 

 inner end of the channel and the distances between each spar 

 buoy, the course to be steered along each leg of the channel also 

 being noted. 



Finally, at the inner end of the channel, the ship passed close 

 east of a beacon which had been constructed on the southern tip 

 of the land. A party was then landed at night on this beacon with 

 a theodolite which was used to observe star sights, thus establish- 

 ing its position. Both ends of the taut-wire traverse had now been 

 fixed, the difference in latitude and longitude of these two posi- 

 tions agreeing within reasonable limits with the differences calcu- 

 lated by working out the taut- wire run between them. The spar 

 buoys were now plotted in their positions relative to the two 

 ends of the channel and the correct courses for each leg were 

 known. It only remained now for the ship to run a number of 

 sounding lines along the axis of this channel, and the approach to 

 Ras at Tannura was established as a safe sea lane. 



This was Challenger's first of many visits to the Persian Gulf and 

 her first task in connection with the export of oil from this 

 unsurveyed coast, in which she was later to play a not insignificant 

 part. It was also her first experience of winter weather in the 

 Gulf, which was quite unexpectedly cold. North-westerly gales, 

 known locally as 'shamals', may blow for many days at a time, 

 raising short choppy seas and filling the air with sand until 

 visibility is down to half a mile. Surveying comes to a full stop 

 on such occasions while the ship tugs at her anchor cable in the 

 exposed anchorages off these flat, featureless coasts; only at the 

 eastern end of the southern shores of the Gulf are there high 

 mountains in sight of the sea, the ranges running south from the 

 vicinity of Muscat. 



The ship called again at Muscat before leaving the Gulf on 

 2 2nd March, 1939. Fuelling at Aden, she went northwards into 

 the Red Sea and to Muhammad Qol on the coast of northern 

 Sudan. 



As well as Admiralty charts, the Hydrographic Department 

 produce and have constantly under revision a formidable library 

 of over 70 books, known to mariners as the Sailing Directions. 



