48 



HYDROGRAPHY. 



of the American Nautical Almanac in 1815, and a set of highly useful 

 nautical tables in 1816, and also a large chart, showing the projection 

 of the " Great Circle Sailing," under the title of " Loxodromic Curve," 

 copies of which I had the honor of presenting to the Honorable 

 Secretary of the Navy from the author, on my first entrance into the 

 navy. By claiming a prior right for a distinguished mathematician, a 

 friend and associate of Adrain, Vateck, Fulton, and other distinguished 

 mathematicians and mechanicians of our country, I only desire to 

 restore to one, and to claim for him the original investigation of this 

 subject, and publication of the chart. I am well satisfied there are 

 few parts of any ocean in which the loxodromic curve can or ought 

 to be attempted; and although the route from the United States 

 to the Brazils is one of those on which it is strongly recommended, 

 I think there are sufficient reasons why vessels should not attempt 

 it. Many have failed entirely, others have but partially succeeded, 

 whilst others, again, have made quick passages. Those voyages which 

 I have examined have derived all their advantages from gaining the 

 line at the most favorable time to take the northeast monsoon of 

 the coast of Brazil, which is fallen in with sometimes as far as 5° to the 

 north of the equator, and at times the wind veers as far to the north- 

 ward as north-northwest ; thus giving vessels, though close to the 

 coast of Brazil, a favorable opportunity to make the passage the 

 whole distance almost on a loxodromic curve, or the shortest distance 

 between two points, — evidently the most desirable to be sought for, or 

 taken, if possible ; yet there are few routes across the ocean where the 

 winds will permit its being taken to advantage at all seasons, except 

 within the trades : these passed, the variables succeed, and change so 

 rapidly, that it is next to impossible to pursue, for any length of time, 

 a course on any loxodromic curve. 



From the equator to 3° south, the set by the Equatorial Stream was 

 south 69° west 75 miles, while from latitude 3° south, longitude 20° 

 west, to latitude 13° south, longitude 30° west, its set was north 80° 

 west, 100 miles; thence to the latitude of Cape Frio it was to the 

 southward and westward. The amount of current between the equa- 

 tor and Rio was north 82° west 300 miles. The greatest set we ex- 

 perienced between latitude 10° north and 13° south, was on the meri- 

 dian of 26° 30' west, 30 miles a day, nearly west. 



The position of Bouvet's Sandy Isle was passed over, but nothing 

 whatever was seen of it. As it was my intention to examine the posi- 



