300 ASTRONOMICAL and 



determinate fpace ; and no fpecific point could be fixed on, as the fwamp is 

 at all times almoft impenetrable, and at this l^albn of the year abfolutely 

 lb without immenfe labour, and expence. It was therefore agreed tliat the 

 termination of a line, fuppofed to be drawn N. 45", E. 640 perches from 

 the mound B, fhould be taken as a point to, 01 near which, a line fhould 

 be drawn from the mouth of Flint river ; which line when drawn, ihould 

 be final, and confidered as the permanent boundary between tlie United 

 States and His Catholic Majefty, provided it palfed not lefs, than one mile 

 north of the mound B : but ii ujion experiment, it fliould be found to pafs 

 within lefs than one mile north of the faid mound, it ihould then be cor- 

 redled to carry it to that dilfance. To obtain as near as poffible the courfe 

 of the faid line, with the diftance between the points to be joined, the fol- 

 lowing materials' deduced from our previous operations were ufed. The 

 longitudes made ufe of are from meafurements, compounded with the 

 eclipfes of the ift fatellite of Jupiter. 



The longitude of the observatory near the mouth of Flint river by tlie 

 eclipfes of the ift fatellite of 1/ is 5'' 39' 19" weft from Greenwich. The 

 lone,itude of our ftation on Thompfon's Creek, by a mean of five good 

 obfervations is 6'' 4' 48" well from Greenwich. From Thompfon's Creek 

 to the Flint river obfcrvatory, the diftance is 371.ii miles, which in the 

 parallel of 31" is equal to 24' 57" in time, which deducted from the lon- 

 gitude at Thomfon's Creek, will leave 5'' 39' 51" for the longitude of the 

 obfcrvatory near the mouth of Flint river ; wlilch difagrees with the longi- 

 tude by obfervation 32" in time. Meafurements when accurately execut- 

 ed, in a known par.illel of -atitudo, are generally preferable to obfervations 

 for diftances, not exceeding loo miles: yet in this cafe, the rneafurement 

 is not entitled to that weight, being done in hafte, with a common chain, 

 through thickets, fwamps, and ponds, where pins of more dian ordinary 

 lennfths had to be made ufe of, which involved an unfurmountablo fourcc 

 of error: but not in fo confiderable a degree as to juftity its rejeftion. It 

 was therefore concluded, that if to twice the longitude of the obfcrvatory 

 near the mouth of Flint river, the longitude by rneafurement from Thomp- 

 fon's Creek be added, and the fum divided by three, the quotient 5^ 31/ 

 30" would be the longitude of the obfcrvatory near the mouth of Flint 

 river, as cnrreftly as it could be had from our materials: But the mouth 

 of Flint river was iound by meaiuremcnt to be 260 perches, equal in time 

 to 3". 3 weft from the oblervatory ; which added to die above determina- 

 tion, the decimal .3 being rejecflcd, as unimportant, v.-hcn errors much 

 larger are unavoidable, will give 5'' 39' 33' for the longitude of the 



mouth of Flint river The latitude has already been fettled at 30° 42' 



42".8. 



The longitude of the obfcrvatory at A, up the St. Mary's by obferva- 

 tion is j"" 29'. The longitude of the obfcrvatory at Point Peter by four 

 good obfervations is 5*" 26' 54" : the difference of longitude by obfervation 

 is 2' 26". — The difference of longitude between the obfervatories, by a 

 traverfe taken for that purpofe, was 37.45 miles wliich is equal to 2' 32". 

 The traverfe being made under very unfavourable circumftances, and con- 

 fifted of an uncommon number of courfes, owing to the fwamps, and 

 ponds, (with which the country abounds), being full of water, and im- 



palfable : 



