During the summer of the present year, the French government directed Captain Bouchet Riviere to make a survey of the Sorelle.  In conclusion, therefore, we will give the following extract from that officer’s letter, as it throws some light upon the circumstances which led to the loss of the Avenger:—­

’The English frigate, Avenger, was lost on the two Sorelle; I saw between the two heads of rocks, which are aptly named ‘Sisters,’ her entire engine, two anchors, a shell gun, and some loose parts of the wreck.  I recovered and took on board some pieces of iron from the bed of the engine, and a boarding cutlass.  The engine lies in a medium depth of ten metres (thirty-three feet).

’From information which has been given me by boats which saw the Avenger at sea the day of her loss, and adding the observations which I was enabled to make on the spot itself, I have every reason to believe that the event happened in the following manner:—­

’The Avenger had, during the day, run along the coast of Algeria, but on the approach of night, being then north of Calle, and the weather having suddenly become very bad, with a great deal of wind from the north-west, the captain of the Avenger altered her course immediately to the northward, in order not to be caught in the middle of a dangerous channel.  As soon as he thought that the ship had passed the parallel of the Sorelle, he resumed his course to the eastward, satisfied that he would pass several miles to the northward of them.  He had not calculated on the currents which I have found at this dangerous spot, and which, with a north-west wind, set to the south-eastward with a rapidity of about 3 miles an hour.  The track of the Avenger must have been materially altered by this cause.  When she steered east, she was only in the latitude of the Sorelle, and was shortly afterwards, on a very dark night, shattered against these rocks.  The first shock must have been dreadful.  It took place on the point south-east of the north-west rock; when she cleared this rock, which is at this spot thirteen feet below the surface, leaving a large white furrow, she ran a hundred and sixty feet further, and struck on the south-east rock, which is only about four feet (one metre twenty centimetres) below the surface.  She again marked the rock very distinctly.  The sea, which is often very rough on this spot, has left nothing remaining but the massive part of the engine, where it can be perceived between the two rocks, covered with thick weed.

’The dangerous Sorelle are formed by two tables of rocks, distant about a hundred and sixty feet from each other, and separated by a channel of a medium depth of thirty-nine to forty-nine feet (twelve to fifteen metres).  These two tables of rocks extend from the north-west to the south-east.  The north-west one has a diameter of 66 English feet (twenty metres), its highest point is to the eastward, 16 feet under water (five metres).  The southeastern has a diameter