the Main, and taking nearly the mid-channel, you are to sound freely between the latitudes of 50° and 53° S., there being good grounds for believing that the bank which unites that group of islands to the continent, is within the reach of the deep-sea lead.
You are then to round Cape Horn, or proceed by the Strait of Magellan, as you may find most eligible, and to make the best of your way to Conception, up to which place it may be supposed that Captain Fitz-Roy has fully completed his survey, although he may possibly have carried it as far as Valparaiso.
This point, however, can be easily ascertained at one of those ports, and from wherever it may appear to have been terminated, you will forthwith begin the great work which has been confided to you by us; or if there should be any doubt about the limits of Captain Fitz-Roy's labours, you may safely commence at Coquimbo, beyond which, in the time consumed by the Beagle, they could scarcely have extended.
When Captain Fitz-Roy's missing despatches arrive, that point will be communicated to you; and if any part of the above interval should not have been examined, and particularly the dangerous banks off Topocalmo, you can easily resume your operations to the southward, so as to include them.
As Rio de Janeiro may be considered the standard point to which it is so convenient to refer the meridian distances obtained on the eastern side of America, so there should be a similar point on the coast of Chili. The choice of that station we leave to you, and there you will again establish the transit instrument, and determine the difference of longitude from Greenwich.
The extent of coasts along the western side of America
