Meantime the guide line was plodding eastwardly through the forests. At 117 miles from the Mississippi the party passed the Hatcha-Lucha (Black Creek) and about 168 miles they crossed the Pascagoula (now Chickasawhay) a little above where the Slapacha (Leaf River) falls in. This last is called Estopacha in other documents of the time. Thence on nothing special occurred until they reached the Mobile River, where the guide line had diverged 517.44 perches too far north. The observatory had been erected before Ellicott's arrival from New Orleans in his schooner by way of Mobile. Observations (solar and lunar, of Castor and Pollux, &c.) were made from March 18 to April 9, 1799. Here the large sector was used, and the transit and equal altitude instrument also. Finally a boundary stone was set up, marked (according to the Journal) on the north "U. S. Lat. 31° 1799," and on the south "Dominos de S. M. C. Carolus IV. Lat 31° 1799." This piece of brown sand-stone, about three feet high is still in place near the Southern Railway and is the basis of all surveys in south-west Alabama.[151] During this time Gillespie went up the river to St. Stephens. With a Haddley's sextant he determined the latitude of that place, and he also made a sketch of the river. Ellicott himself determined the latitude of Mobile and the point at the mouth of the Bay. Among the most serious problems of the survey was carrying the line across the Mobile River and adjacent swamps. The only feasible way was found to be for parties on each side to make fire and smoke signals at certain intervals on the high lands to the east and west. While Ellicott was at Pensacola, with Colonel Hawkins, trying to arrange with the Spanish commandant to secure the neutrality of the Creeks, his party pushed the line forward from the Mobile to the Escambia and Coenecuh Rivers above their junction. The matter of the Indians was never satisfactorily arranged, but the survey proceeded. On the Coenecuh, however, he notes that the more pressing enemies were flies and "musquitoes," which made every observation a matter of great pain. Among these was the transit of Mercury in May, 1799. Thereafter they crossed the White Cedar Creek, Yellow Waters, and between the 321st and 334th miles crossed and re-crossed the larger Choctaw River, now the Choctawhatchee, and its branch, the Pea River. Between that and the Chattahoochee were a number of streams and lakes, but he names only the Waters of Chapully (Chipola River.) In fact, little or no account is given of this part of the survey, as Ellicott was not in the party. He sailed from Pensacola and finally met the others on the Chattahoochee.