«?6 



CORRECTION OF LONGITUDES IN THE WEST INDIES, 



VIII. 



Remarks on some Points of Hydrography, by Mr. Leblanc, 

 Officer in the French Ravy*< 



Errour of Ion- JL Hfc ejulf of Florida, or new Bahama Channel, is greatly 



rida. 



Corrected. 



gitude in the . 



Gulf of Flo- frequented by ships ot all nations, that trade to or cruise in 



the Gulf of Mexico ; yet the latitudes and longitudes of 

 the principal points in it have not been fixed. They are 

 not mentioned in the Tables inserted in our Connoissance 

 des Temps, or in the English collection entitled " Tables 

 requisite &c." Accordingly we are obliged to have recourse 

 to the most modern charts. French navigators use the Ge- 

 neral Chart of the Atlantic Ocean published inl791, and re- 

 vised and corrected in 1792. I think I can show, that there 

 exists an errour in longitude of 52' with respect to all the 

 points of the gulf. I was led to notice this on the following 

 occasion. 



On the 25th of January, i907, in the afternoon, on board 

 the Foudroyant, we saw waves and breakers on the North of 

 the Great Bahama. At 4 o'clock we set, at a small distance, 

 Lena Key N 80° E, and that of Azena N 45° E by com- 

 pass. The longitude given by our time-keepers No. 40 

 and 76, reduced to (hat hour, was only 80° 17 30", while 

 that by the chart was nearly 82° 15'. Whence it follows, 

 that the whole course of the gulf is too far west about 5 C 2' 

 of a degree f , a considerable errour in those latitudes. The 

 going and state of the tvvo timekeepers had been carefully 

 observed during our long stay at the Havannah. Their er- 

 rburs were almost nothing after we had been at sea eight 

 days, when we had soundings abreast of Cape Henry. The 

 results given by the observations taken with the reflecting 

 circle gave us no reason to suspect any thing incorrect in 

 the longitudes : and when we entered Brest the absolute 

 errour of No. 40 was only 7' of a degree after a voyage of 

 thirty-five days. 



Green Key is one of the priucipal marks of the Old Ba- 



Old Bahama 

 channel. 



* Journal de Physique, vol. LXV, p. 55. 



t I give the difference as in the original, not knowing where the 

 errour is. 



hums 



