40 



HYDROGRAPHY. 



the south-southeast, which gradually grew more perceptible until we 

 reached them. We crossed the equator in 17° west, and sounded for 

 the Triton Bank, under the longitude of 17° 46' west, and latitude 

 0° 32' south, keeping the lead constantly going ; but no appearances 

 of a shoal, either in the color of the water, tide rips, or soundings, 

 were perceptible. The current setting to the northward had influ- 

 enced us very considerably for the last few days before reaching the 

 equator. 



In passing through this space between the north and south trades, 

 we observed the upper strata of clouds passing rapidly from the east- 

 ward. 



From the number of rips encountered, and the variation of the tem- 

 perature of the water from 3° to 5° between them, I suspected that a 

 current of some magnitude existed ; but after making frequent trials, 

 it was found of very little strength, and running to the east-northeast. 



The winds, until we reached the equator, prevailed from south- 

 southwest to south-southeast, generally light, inclining to calm ; those 

 experienced by the Relief were very similar 15 days later. 



The set by current of the squadron from Porto Praya to the line, in 

 24 days, was north 25° east 132 miles. The Peacock experienced it 

 north 56° east 144 miles in 23 days, and the Relief north 48° east, 

 203 miles in 25 days. 



A variety of opinions have always been held on the subject of the 

 best meridian on which to cross the equator ; I propose to say a few 

 words upon it, having found it almost impossible to arrive, after exa- 

 mining all of them, at any satisfactory result. In my opinion, the sea- 

 son of the year ought alone to be the guide ; that which controls more 

 than anything else, being the monsoons of the coast of Brazil. During 

 the prevalence of the southerly monsoon, it is extremely disadvanta- 

 geous to cross the line too far to the westward, for after being so fortu- 

 nate as to pass Cape St. Roque, the prevailing winds may be found to 

 the southeast, and sometimes as far as south, thereby driving a vessel 

 upon the coast, and subjecting her to tack to the eastward again, and 

 consequently to a very long and tedious passage. On the other hand, 

 during the northerly monsoon, a vessel pursuing a more westerly route 

 would meet with no detention, but, on the contrary, having the wind 

 to the northward and eastward, at times as far as north-northeast, she 

 would be enabled to make rapid progress, with a free wind on a line 

 parallel with the coast. It is thus evident that the equator may be 



