400 APPENDIX. 
ORDERS FOR THE RELIEF. 
The watch officers to be divided the same as on board the Porpoise, 
as follows : . . 
1st watch, Lieutenant Pinckney and Passed Midshipman Davis. 
2d watch, Lieutenant Case and Passed Midshipman Cummmgs. 
3d watch, Lieutenant Underwood and Passed Midshipman Sin- 
clair. 
Lieutenant Case, when his other duties will permit, will assist in 
the naturalist department. 
Dr. Palmer will be attached to the scientific department, as assis- 
tant to Dr. Pickering and Mr. Couthouy, Naturalist. 
Midshipman Blair will be excused from watch for boat duty. 
Lieutenant Underwood will be employed in sketching, &c. 
Charles Wilkes, 
Commanding Exploring Expedition. 
U. S. Ship Vincennes, 
At Sea, November 21st, 1838. 
XX. 
U. S. Ship Vincennes, 
Rio de Janeiro, December 15th, 1838. 
Sir, 
You will proceed and make a survey of a shoal said to exist off 
Cape St. Thomas, about sixty miles north of Cape Frio, with the 
Peacock, Porpoise ,* Sea-Gull, and Flying-Fish, which are placed 
under your command for the duty. 
This shoal is supposed to be about twenty miles east-half-north 
from Cape St. Thomas. 
In surveying it, as far as I am able to judge of its locality, I would 
recommend the following mode to be pursued, viz. : 
On your arrival at or near its supposed locality, anchor your four 
vessels at convenient distances from each other, within a suitable 
distance for admeasurement by sound. Here ascertain your latitude 
and longitude accurately, measure your distance between all the 
vessels by sound, firing guns in succession, noting the elapse of time 
* The Porpoise was not on this duty ; these orders were countermanded, as she could 
not be prepared for sea in season. 
