THERMOMETRICAL OBSERVATIONS. 299 



The fame number of ft.irs were taken with each fciior ; but the large 

 one from tlie length of its radius, being at lead three times as accurate as 

 the fmall ons, the latiiude by the large one, was multiplied by three, and 

 tlie latitude by the fmall one added to that produfl, and the fum divided 

 by four, the quotient 30° 21' 39". J was taken for the true latitude of the 

 obfervatory. 



This being the higheil point to which we cculd afcend the river, and the 

 country fo covered with water, that it was impoffible with our few remain- 

 ing broken down pack hcrfes to convey our apparatus by land to the fource 

 of the river : we therefore had to determine the geographical pofition of 

 its fource by a traverfe ; the courfes of which are as follows : viz. begin- 

 ning at the obfervatory A, (Plate XII.) where a hewn poft was fet up and 

 furrounded by a large mound of earth, from thence N. 10° i' W. 4435.6 

 perches, thence S. 85° 14' W. 1 15.6 perche^', thence north 44. 8 perches 

 at the end of which a hewn poR; was fet up, and furrounded by a mound 

 of earth B. — Thefe courfes when tabled will ftand as below. 



Courfes. 

 N. 10" i' \V. 44^5.6 pn I 4368 



s. 85° 14' w. iTs.e p* 



N. 44 8 p\ 



The laft nwhticned mour.d of earth was thrown up on the margin of 

 tlis Okefonokc lv.-amp, and as near to it as any permanent mark could be 

 placed on account of the water. 



From Plate XII. upon which the .-ibove tr.averfe is laid down, it may be 

 feen that the river St. Mary's is formed by the water draining out of the 

 Okefonoke fwamp along feveml marfhes, or fmall fwamps, which join irao 

 one, and form, or conRitute the main branch or body of the river. Tlie 

 principal, or largefl of thofe fwamp';, or drains, is the moll eafterly cnc,, 

 and in which the current is the moft vifible. Tliis marfh, or drain is crof- 

 fed by the laft courfe cf the tnivcrfe, which tefminales at the mound B. 

 From this mound norlh-eafterly into the Avamp, the v^-ater has but little, 

 if any perceptible current. The fource of the river is therefore in an in- 

 determinate 



