S6 
order to extend the triangulation. He then sailed from the 
quay of Salina, near the Estacada, in the canoe fitted out as 
before-mentioned, and passing between the islands of Monapos- 
tiac and Natar-tiac he arrived at San Dionisio, the sounding line 
constantly showing nearly six metres (20 feet) depth of water, 
the bottom being mud and shingle, both easy to remove. 
It was supposed before this exploration that the lower lake 
extended as far as the bar of Tonala about 38 miles to the east 
of the Boca Barra leaving between the lake itself and the Pa- 
cific a narrow strip of land, designated by the name of the is- 
land of St. Francisco. It was believed, also, that the whole of 
the lake was nothing else but a creek of little depth and of no 
importance, as is the western part of it, known likewise by the 
names of leigoon of Tilema, and Dead Sea. However, on as- 
cending the hill of Umalalang, which overlooks the village of 
St. Dionisio, this erroneous impression was soon dispelled, by 
observing that the ground to the east of Boca Barra extends 
itself considerably, and contains other lakes of some extent. 
On proceedmg thither, the eastern part of the lower lagoon 
attracted Sr. Moro's attention, as he could not but observe 
that its vicinity to the Boca Barra and the canal of Santa Te- 
resa, its considerable depth and excellent bed, and the circum- 
stance of being so well sheltered from the prevailing winds, fit- 
ted it admirably for a commodious and safe anchorage. 
Whilst Captain Robles, an oflicer of the Engineers, who had 
lately joined the Commission, was surveying a portion of this 
lake, Si. Moro proceeded with Lieutenant Guido to explore the 
Boca Barra. The tide, which was beginning to ebb, produced 
a current that did not allow them to steer their imperfect craft, 
and was carrying them towards the sea with such force, that 
they clearly saw by the effort necessary to keep their position, 
that it would be impossible to surmount its impetus so as to 
effect their return, should they be carried out. The tide was 
too strong to use the sounding line, but it was evident that a 
sand bank obstructs internally the Boca Barra throughout its 
whole length from east to west, and it appeared to be impor- 
tant to investigate tlie cause which might have produced it. 
As the idea that a canal f)f great dimensions was the only 
