THE AUSTRALIAN GREAT BARRIER REEF. 95 



"3. When you have examined them all, and considered their several advantages and difficulties, and determined 

 which of them will offer the speediest and safest passage for the generality of merchant vessels, you will endeavour 

 to devise some practical means of marking them by beacons of wood, stone, or iron, so placed on their outer 

 islands or cays, that they may serve to guide those vessels to a certain and safe landfall. 



"4. The position and dimensions of the several detached reefs and shoals which lie to the southward of the 

 (jreat Barrier, and which appear, though with long intervals, to stretch towards Howe Island. 



" 5. The Bellona, Bampton, Mellish, and other reefs to the westward of New Caledonia may be considered 

 as one large group, and are probably the remnants of a ridge of submarine hills, which, taking a parallel direction 

 to the barrier, form, between it and them, the wide sea channel of approach to the barrier openings. All these 

 rocks, as well as the Farquhars, must be explored and charted so as to define the eastern and western limits of 

 that channel. 



" 5. In the more immediate mouth of Torres Strait, the reefs, islands, and intervening passages, having been 

 discovered at different periods, and laid down by different authoritie.s, assume a most complicated appearance, but 

 by carefully collating what has been done by Flinders, Bligh, King, and other navigators, you will probably succeed 

 in fixing on some comparatively safe channels, by which vessels may pass through from the eastward, and you will 

 consider this to be one of the most important objects of the expedition. 



" 7. In Torres Strait it does not appear that to the northward of Prince of Wales Islands any good channels 

 will be found, and we do not wish that you should spend any valuable time there, nor even between them and 

 Endeavour Strait ; but of this latter strait a complete survey, with its tides and soundings, with clear sailing 

 directions, and with its dangers well distinguished by any sea-marks that can be adopted, will be a real boon to 

 the mariner." 



The instructions and suggestions embodied in the foregoing Admiralty orders were faith- 

 fully and successfully carried out, although with the result of the Raine Island Passage being- 

 elected, as giving the most ready access to Torres Strait from the Pacific Ocean outside the 

 Barrier. This passage, as is mentioned in the introductory^ notice, was afterwards abandoned in 

 favour of the wider and more northern Bligh (or Great North-East) Entrance, in consequence of 

 the extreme intricacy' of the route through the reefs at this point, and the absence of Cjheltered 

 anchorage in its vicinity. The most gratifying fact associated with this survey was the 

 appointment of the accomplished geologist, Professor J. Beetc Jukes, as naturalist to the 

 expedition. From his pen subsequently emanated that standard work, "Narrative of the Sur- 

 veying Voyage of H.M.S. Fly," which embraces the most ample information extant concerning 

 the conspicuous structural features of the Australian Great Barrier Reef. 



In order to place the reader thoroughly en rapport with the chief topographical details 

 hereafter given, a map of Queensland, including the Barrier district and the more important 

 recorded soundings, has been reproduced from the Admiraltj' charts as an accompaniment to this 

 chapter. 



In the following general description of this most remarkable coral edifice, which will now 

 be proceeded with, those prominent features the discovery and the record of which were origi- 

 nally associated by jukes with the Flv narrative will as far as possible be embodied in con- 

 secutive succession, with due ackiKiwledyments. 



