through the medium of the following instructions from the Admiralty, for
the use of which I am indebted to Lieutenant C.B. Yule, who succeeded to
the command of the Rattlesnake, upon the death of our late lamented
Captain, at Sydney, in March 1850, after the successful accomplishment of
the principal objects of the expedition.

BY THE COMMISSIONERS FOR EXECUTING THE OFFICE OF LORD HIGH ADMIRAL OF THE
UNITED KINGDOM OF GREAT BRITAIN AND IRELAND, ETC.

Whereas, it being the usual practice of vessels returning from the
Australian Colonies, or from the South Sea, to proceed to India through
Torres Strait; and most of those vessels preferring the chance of finding
a convenient opening in the Barrier Reefs to the labour of frequent
anchorage in the Inshore Passage, it was thought fit to send out an
expedition under Captain Francis Blackwood, to determine which was the
best opening that those reefs would afford, and to make such a survey
thereof as would ensure the safety of all vessels which should continue
to adopt that mode of reaching the Strait:

And whereas, although that specific object was successfully achieved by
the survey of Raine Island Passage, and by the erection of a durable
beacon there to render it the more accessible, yet it appears that much
is still to be done in those seas in order to make the approach to the
Strait more secure and certain, as well as to afford the choice of
another entrance farther to the northward in case of vessels overshooting
the latitude of Raine Island by stress of wind, or current:

We have, therefore, thought proper to appoint you to the command of the
Rattlesnake, for the purpose of carrying out these objects; and you are
here by required and directed, when that ship is in every respect ready