N. W. Point of the Lake of the Woods. 51 



By interpolating between two successive moments at whicli 

 the difference from the mean time of the one place is known, 

 we can now find the difference from the mean time of that 

 place in the same moment in which the difference of the 

 Chronometer from the mean time of the other place was as- 

 certained by actual observation, and thus determine the dif- 

 ference of longitude between the two places. In this man- 

 ner we find by the three combinations of which the observa- 

 tions admit, the following results. 



MEAN TIME OF 



Mr. Thompson's Monu- 

 ment No. 1, July 28, 



Station near the Rat Port- 

 age, July 29, 



Mr. Thompson's Monu- 

 ment No. 1, July 31, 



MEAISr TIME OF 



Station near the Rat Port- 

 age, July 29, 



Mr. Thompson's Monu- 

 ment No. 1, July 31, 



Station near the Rat Port- 

 age, Aug. 1, 



MEAN TIME OF 



Mr. Thompson's Monu- 

 ment No. 1, July 31, 



Station near the Rat Port- 

 age, Aug. 1, 



Mr. Thompson's Monu- 

 ment No. 1, Aug. 4, 



004 



875 

 202 



875 

 202 

 504 



202 

 504 

 004 



DIFFERENCE OF LONGITUDE. 



True Intervals 

 in mean time. 



Days. 

 1.869 



1.329 



1.-329 

 1.300 



1.300 

 2.502 



Between the two Stations. 



Arnold 2111. Morice 201 



2' 20" 59 



2 21 77 



2 22 95 



2' 21" 07 



2 21 71 



2 21 85 



Mean Result of each Chronometer, 

 Mean of all Results. 



2 21 77 2 21 54 



Difference of Longitude between Mr. Thompson's Monu- 

 ment and the Station near the Rat Portage, — 2' 21" 65 



Mr. Thornpson's Monument No. 1 is not the most north- 

 west point in that vicinity. The bay on which it is placed 

 extends about a mile farther, and terminates in a small pond 

 which is free from rushes, and not fed by any considerable 

 JDrook. Beyond this point, there is a swamp, which no doubt 

 is part of the lake in the spring and fall of the year ; but I 

 have considered as the termination of the lake, in the north- 

 west direction, the extreme northwest point of the pond, 

 which we reached by paddhng, without any difliculty, in the 

 loaded canoe. 



