PASSAGES. 



43 



useful purposes in navigation. The discolored water to windward of 

 Barbadoes and that of the False Brazil Bank are well-known examples. 



The deep sea temperature at the depth of 350 fathoms was 23° less 

 than that of the surface. 



The reputed shoals, on which it is said the Maria and Bon Felix 

 struck, are on this route; the former is said to be in latitude 19° 45' 

 north, longitude 20° 50' west, and the latter in latitude 19° 20' north, 

 longitude 20° 37' west. Both of these situations were passed over, by 

 the squadron, in the manner I have before described, and the examina- 

 tion of the localities fully satisfied us that no such shoals exist where 

 they are laid down. It is to be hoped that this evidence will have 

 the effect to erase these supposed dangers from the charts. 



On this passage we found the current trending to the northward and 

 eastward, from one-half to five-eighths of a knot per hour, but there 

 was none most of the time. Many navigators give it as setting to the 

 southwest. The set of the ship by current in the whole passage was 

 found to be north 57° east, 42 miles in 13 days. 



The Bonetta Rocks, in latitude 16° 32' north, longitude 20° 57' 

 west, said to lie to the eastward of Bonavista, and nearly in our track, 

 I determined to make search for. Although the account given in 

 Purdy's Atlantic Memoirs appeared so well authenticated, and the 

 failure to find them after so diligent a search as that made by H. B. 

 M. Ship Leven, Captain Bartholemew, left but little hope of our being 

 more successful, yet I considered the sweeping over the locality with 

 the squadron would be, as I have before stated, still more satisfactory ; 

 we therefore passed over this locality, as well as an area of ocean of 

 from 40 to 50 miles in extent in the neighborhood, with the lead 

 continually going to the depth of from 60 to 70 fathoms, and good 

 look-outs both below and aloft, the sea being quite smooth ; we also, 

 after having passed over the position assigned them, continued to steer 

 on their reported bearing, towards the island of Bonavista, but saw 

 nothing of them. It appears that in the year 1841, the British Ship 

 Charlotte was wrecked on a shoal which was reported in latitude 

 16° 17' north, longitude 22° 21' west; the nearest we approached this 

 position was eighty-two miles, on a bearing of north 79° west. I am 

 still inclined to doubt the accuracy of this position, as it appears to 

 have been passed over by H. B. M. Ship Leven in her search. Should 

 the rocks be hereafter seen, I have little doubt that their true position 

 will correspond to that of the Hartwell Reef, on which a ship of that 

 name, and the Madelaine, were both lost. 



