121 [ 237 ] 



upon one of which, in particular, he could place great reliance. He had 

 not the opportimity of observing, himself, for the time, at New Orleans ; 

 but adopted it as furnished to him by Mr. Lelley, who rates and regulates 

 chronometers habitually, and who is provided with a transit instrument for 

 the purpose. The difference between the two places he found to be, by the 

 means of the three chronometers. 2tn. 26.35., which, combmed with the 

 longitude of the liglit-house station, as determined by Capt. Talcott, gives 

 for the longitude of New Orleans Cathedral 5/i. 59w. 52.15. 



Mr. Edmund Blunt, now one of the principal assistants in the coast sur- 

 vey of the United States, has also furnished me, in this regard, with the re- 

 sults of the observation of two chronometers which have been used in 25 

 voyages between New Orleans and Brooklyn. The mean of the three dif- 

 ferent methods of rating, habitual among those who regulate marine chro- 

 nometers, has been taken for the difference of time between the two places. 

 The longitude of Brooklyn has been given directly by chronometers trans- 

 ported there from Greenwich, on board the steamer British Q,ueen, during 

 three trips of that vessel ; the mean of which has been taken, and the same 

 longitude, to little more than 1", has been given by direct comparison with 

 the City Hall of New York, whose longitude has been determined by the 

 solar eclipses of May, 1836, and September, 1838. The mean of those two 

 comparisons has been taken by nie as the longitude of Brooklyn ; and the 

 combination of this with the mean of the chronometers, as above said, has 

 given for the longitude of New Orleans Cathedral 5/i. 59ni. 59.665. 



These later results come quite near to the earlier ones of the French 

 academicians and of the Requisite Tables, to which, of course, we must 

 allow proportionate weight, and seem almost to confirm them. Now, 1 do 

 not mean to say that Ferrer's longitude, or that given by Mr R. T. Paine 

 in the American Almanac, is too great by 20 or 24 seconds : it is repugnant 

 to decline the authority of such zealous and intelligent observers; and I by 

 no means intend that what I at present offer is to be taken as decisive of a 

 question which, for settlement, would demand a fuller and more minute in- 

 vestigation than is suitable here. But, bein^ obliged to adopt a longitude 

 for insertion in the Table of Geographical Positions, I have taken it as fol- 

 lows : 



h. 



Longitude stated by the French academicians - - 5 



Requisite Tables - - 5 



Chronometer comparisons of Majop Graham - - 5 



from Mr. Blunt - - 5 



of 1. N. Nicollet - - 6 



And the mean longitude of New Orleans Cathedral - 5 59 56.25 



Longitude in arc - - - 89«> 59' 3".75 



It is to be hoped that future geographers will avail themselves of oppor- 

 tunities that may be afforded them in visiting this point, to contribute to 

 the clearing up of the discrepancy yet existing, and to the determination of 

 the absolute longitude of this important place. 



1. N. NICOLLET. 



Baltimore, February 25, 1843. 



