51G APPENDIX. 



Rodriguez Shoal, in longitude 155° W., where it is supposed to exist, 

 and examine and survey it. 



If you should obtain any information of islands or shoals, laying in 

 or near your track, you may make a deviation ; but as soon as you 

 have completed your search, you will resume the course pointed out 

 to you, which must be strictly adhered to, as any deviation therefrom 

 may interfere with the track of the rest of the squadron, and cause a 

 waste of time. 



In making search for land, you will draw circles of your visual 

 horizon, and be particular not to omit examining the space carefully. 



You may select such an island as may seem to you most advanta- 

 geous to use the boring apparatus ; landing thereon a party under a 

 careful officer, (Lieutenant Johnson,) whom you will specially instruct 

 in its use, carefully preserving the borings for every foot in depth, in 

 boxes properly marked ; the armourer and forge will of necessity 

 accompany the party. 



You will be particular in giving Lieutenant Johnson instructions 

 relative to the preservation of the health of the party, taking every 

 precaution not to come in collision with the natives, if any should 

 be on the island ; and equally cautious to guard against surprise or 

 treachery on the part of the natives. 



You will take care to furnish the party with ample supplies. 



The General Order in relation to intercourse with the natives, will 

 be observed during your cruise as heretofore. 



Tides will be carefully observed by the shore-party hourly. 



You will obtain the transverse sections of at least three of the coral 

 islands (the one on which the boring apparatus is used being one of 

 them), with the level and soundings, inside and out, on all the points 

 of the island where it is possible to obtain them, in connexion with an 

 accurate survey of the same. 



On your arrival at Matavai, you will be very particular in obtain- 

 ing sights (equal altitudes) for your chronometers, and also on all the 

 islands you may discover or survey. 



You will also try the dip and intensity, both at sea and on shore, 

 whenever practicable. 



Between thirty and forty days is deemed ample time to secure the 

 success of the boring experiment, which it is recommended should be 

 continued throughout the twenty-four hours, which may easily be 

 effected by a proper division of the force employed. 



I do not designate any particular island on which the boring experi- 

 ment is to be made : this must depend upon how you fall in with the 

 Paumotu Group. I would have you select one at as early a period as 



