Latitude, 10 deg. 41' south; longitude, 73 deg. 41' west of Greenwich; elevation above sea-level, 661 feet; distance from the Atlantic, 3142 miles; depth of water, 12 feet. ESPERANZA. Esperanza is situated on the Perene river about 11 miles above the junction of the Ene and Perene, which form the Tambo. The navigation for steamers drawing 10 feet of water terminates at the junction of the Perene and Ene. From thence to Fort San Ramon, a distance of sixty miles, canoes could navigate, but with some difficulty, owing to the swiftness of the current, which at San Ramon runs at the rate of 6 miles per hour. Small stern-wheel, flat-bottomed steamers, such as are in use on the swift, narrow and shallow rivers west of the Mississippi, could probably be employed with success in establishing communication between Fort San Ramon and the Ucayali. LIST OF DISTANCES ON THE UCAYALI RIVER. Ucayali River. Miles. Atlantic ocean to mouth of the Ucayali 2189 (Amazon River.) Mouth of the Ucayali to Pucacura 293 Pucacura to Sarayacu 96 Sarayacu to Pacamashi 155 Pacamashi to Yarinacocha 67 Yarinacocha to mouth of the Pachitea river 91 Mouth of the Pachitea to Vuelta del Diablo 200 Vuelta del Diablo to confluence of the Tambo and Urubamba 51 Confluence of the Tambo and Urubamba to the Ucayali, source of the Urubamba river, a continuation of the Ucayali 375 Ucayali river, from its source to the Atlantic 3517 Distance from the Atlantic to the head of steamer navigation on the Ucayali 3142 PACHITEA RIVER. The banks of the Ucayali and Pachitea, at their confluence, are low, subject to overflow and unsuitable for settlement. About nine miles above its mouth we come to the first Indian village on the Pachitea, a male Conebo hamlet, with nothing to recommend it except that it is situated on ground a little higher than the flats which surround it. On the left bank of the Ucayali a few miles below the mouth of the Pachitea, there is a place called Hoje, which is not subject to overflow at high water, but in other respects it is not an eligible position for a town or post. The Pachitea is navigable at low water for steamers drawing nine feet of water to the confluence of the Palcazu and Pichis rivers. MOUTH OF THE PACHITEA. Latitude, 8 deg. 43' 30" south; longitude, 74 deg. 32' 30" west of Greenwich; magnetic variation, 8 deg. 45' 40" east; thermometer, 75 deg.; elevation above sea-level, 508 feet; distance from the Atlantic, 2891 miles; current, 3 miles per hour; width of the Pachitea at its mouth, 400 yards.