N. W. Point of the Lake of the Woods. 53 



Eat Portage Station, and most northwest point of the Lake 

 of the Woods, in the vicinity of Mr. Thompson's Monu- 

 ment No. 1. 



Difference of meridional parts. Difference of longitude. 



33' 977 35' 6375 



It is therefore evident, that, according to the observations, 

 Mr. Thompson's Monument No. 1, is a Httle more northwest 

 than the station near the Rat Portage ; but the most north- 

 western point of the lake in the vicinity of Mr. Thompson's 

 Monument No. 1, is considerably more northwest than the 

 station near the Rat Portage, and is, therefore, agreeably to 

 the principles explained in this report, the most northwest- 

 ern point of the Lake of the Woods. 



With regard to the accuracy of the observations, I beg to 

 remark— 1. That the angles by which the latitudes are de- 

 termined are all read off on the same, or nearly the same, 

 divisions of the sextant, and that, consequently, all errors, 

 which the sextant may have, are common to both latitudes, 

 and do not affect the difference of latitude on which the re- 

 sult chiefly depends. 2. The difference of longitude being 

 correct, it would require an error of more than one minute 

 in one of the latitudes, or an error of more than thirty seconds 

 and of contrary sign in each, to change the result derived 

 from the observations. 3. The agreement of the two 

 chronometers shows, that the difference of longitude cannot 

 be far from the truth. 4. If there should be any doubt res- 

 pecting the observations for time depending on single alti- 

 tudes, on account of the possible errors of the instrument, it 

 is to be observed that these errors would be too small to af- 

 fect the result, and that nearly the same difference of longi- 

 tude may be derived from the equal altitudes only which are 

 not liable to the same objection. 



The sun's declination, and the equation of time, have been 

 calculated from the Nautical Almanack, on the supposition 

 of the longitude of the station near the Rat Portage being 

 94° 39' west of the Royal Observatory at Greenwich, which 

 would give the longitude of the most northwestern point of 

 the Lake of the Woods, in the vicinity of Mr. Thompson's 

 Monument No. 1, 95" 14' 38" west of the same place. 



JVbfe.— Mr. Tiarks made oath in New- York, Nov. 18th, 1825, before Judge 

 Irving, to the truth and correctness (to the best of his knowledge) of the above 

 report. 



