May 16. Le Saumal.  Marseillette.  May 17. Marseilleite.  Carcassonne.  From Saumal to Carcassonne we have always the river Aube close on our left.  This river runs in the valley between the Cevennes and Pyrenees, serving as the common receptacle for both their waters.  It is from fifty to one hundred and fifty yards wide, always rapid, rocky, and insusceptible of navigation.  The canal passes in the side of hills made by that river, overlooks the river itself, and its plains, and has its prospect ultimately terminated on one side by mountains of rock, overtopped by the Pyrenees, on the other by small mountains, sometimes of rock, sometimes of soil, overtopped by the Cevennes.  Marseillette is on a ridge, which separates the river Aube from the Etang de Marseillette.  The canal, in its approach to this village, passes the ridge, and rides along the front, overlooking the Etang, and the plains on its border; and having passed the village, re-crosses the ridge, and resumes its general ground in front of the Aube.  The land is in corn, saintfoin, pasture, vines, mulberries, willows, and olives.

May 18. Carcassonne.  Castelnaudari.  Opposite to Carcassonne the canal receives the river Fresquel, about thirty yards wide, which is its substantial supply of water from hence to Beziers.  From Beziers to Agde the river Orb furnishes it, and the Eraut, from Agde to the Etang de Thau.  By means of the ecluse ronde at Agde, the waters of the Eraut can be thrown towards Beziers, to aid those of the Orb, as far as the ecluse de Porcaraigne, nine geometrical miles.  Where the Fresquel enters the canal, there is, on the opposite side, a waste, to let off the superfluous waters.  The horse-way is continued over this waste, by a bridge of stone of eighteen arches.  I observe them fishing in the canal, with a skimming net of about fifteen feet diameter, with which they tell me they catch carp.  Flax in blossom.  Neither strawberries nor peas yet at Carcassonne.  The Windsor-bean just come to table.  From the ecluse de la Lande we see the last olive trees near a metairee, or farm-house-, called La Lande.  On a review of what I have seen and heard of this tree, the following seem to be its northern limits.  Beginning on the Atlantic, at the Pyrenees, and along them to the meridian of La Lande, or of Carcassonne; up that meridian to the Cevennes, as they begin just there to raise themselves high enough to afford it shelter.  Along the Cevennes, to the parallel of forty-five degrees of latitude, and along that parallel (crossing the Rhone near the mouth of the Isere) to the Alps; thence along the Alps and Apennines, to what parallel of latitude I know not.  Yet here the tracing of the line becomes the most interesting.  For from the Atlantic, so far we see this production the effect of shelter and latitude combined.  But where does it venture to launch forth unprotected by shelter, and by the mere force of latitude alone?  Where, for instance, does its northern limit cross the Adriatic?  I learn, that the olive tree resists cold to eight degrees of Reaumur below the freezing-point, which corresponds to fourteen above zero of Fahrenheit:  and that the orange resists to four degrees below freezing of Reaumur, which is twenty-three degrees above zero of Fahrenheit.