41 
than the plain of Tarifo, by more than 2Gi feet ; but as the 
most northern of the two chains between which the rivers Chi- 
capa and Monetza are enclosed has no interruption whatever, 
Sr. Moro thought it possible to convey along its side the waters 
of the first of those two rivers as far as Tarifa, from whence 
they might be distributed to both seas; neither did he consi- 
der it difhcult to surmount the natural barrier formed by the 
small chain of Convento, between the valley of the Monetza 
and the table-land of Tarifa. The hill of Convento rises al- 
most isolated, and the gaps on both sides, especially the nor- 
thern, is of so trilling an elevation above the ground, that a 
cut through the latter would be an almost insignificant under- 
taking. 
This discovery induced Sr. Moro at once to give up the idea 
of his returning to the Coatzacoalcos with the view of surveying 
its course, and this operation was entrusted to Messrs. Robles 
and Gonzalez, who immediately proceeded thither for the 
purpose. 
Meanwhile Sr. Moro directed that Lieutenant Guido should 
station himself at Tarifa with a barometer, whilst he, following 
the dale of the Chicapa, took with him another to the place 
called the Ultimo Rancho. 
Two series of barometrical observations performed simul- 
taneously in two successive days, and under the most favour- 
able atmospherical circumstances, showed that these two points 
are on the same level, whilst about 1^ miles higher up from 
the spot in which Sr. Moro stationed himself, the river forms a 
cascade of nearly 23 feet high. 
From San Miguel to the Ultimo Rancho five constant 
streams join the Chicapa, and having measured the vvaters of 
this river in a point below its junction with these streams 
they were fomid equivalent to more than 5 metres or 176 
cubic feet per second, so that by adding to it the Monetza, 
and the stream which runs through San Miguel, called Xoxo- 
cuta, a body of waters of about seven cubic metres or 21-7 
cubic feet may be reckoned upon. According to all the 
information collected, these waters were then in a state which 
