[Balabac straits.] After the night set in, we continued sounding every ten minutes, and occasionally got bottom in from thirty to seventy fathoms.  At midnight, the water shoaled to twenty fathoms, when I dropped the anchor until daylight.  We shortly afterwards had a change of wind, and a heavy squall passed over us.

In the morning we had no shoal ground near us, and the bank on which we had anchored was found to be of small size; it is probable that we had dropped the anchor on the shoalest place.  Vessels have nothing to fear in this respect.

At 9:00 a.m. of the 8th, we made the Mangsee Islands ahead of us, and likewise Balabac to the north, and Balambagan to the south.  Several sand-banks and extensive reefs were also seen between them.  On seeing the ground on which we had to operate, of which the published charts give no idea whatever, I determined to proceed, and take a central position with the ship under the Mangsee Islands; but in order not to lose time, I hoisted out and dropped two boats, under Lieutenant Perry, to survey the first sand-bank we came to, which lies a few miles to the eastward of these islands, with orders to effect this duty and join me at the anchorage, or find a shelter under the lee of the islands.

At half-past two p.m. we anchored near the reef, in thirty-six fathoms water.  I thought myself fortunate in getting bottom, as the reefs on closing with them seemed to indicate but little appearance of it.

The rest of the day was spent in preparing the boats for our operations.  I now felt the want of the tender.  Although in the absence of this vessel, great exposure was necessary to effect this survey, I found both officers and men cheerful and willing.  The parties were organized,—­the first to proceed to the north, towards Balabac Island, to survey the intermediate shoals and reefs, under Lieutenant Emmons and Mr. Totten; the second to the south, under Lieutenants Perry and Budd; and Mr. Hammersly for the survey of the shoals of Balambangan and Banguey, and their reefs.  The examination of the Mangsee Islands, and the reefs adjacent, with the astronomical and magnetic observations, etc., devolved on myself and those who remained on board the ship.

The weather was watched with anxiety, and turned out disagreeable, heavy showers and strong winds prevailing; notwithstanding, the boats were despatched, after being as well protected against it as possible.  We flattered ourselves that these extensive reefs would produce a fine harvest of shells; but, although every exertion was made in the search, we did not add as many to our collections as we anticipated.  Some land-shells, however, were found that we little expected to meet with, for many of the trees were covered with them, and on cutting them down, large quantities were easily obtained.  Mr. Peale shot several birds, among which was a Nicobar pigeon; some interesting plants and corals were also added.  On the island a large quantity of drift-wood was found, which with that which is growing affords ample supplies of fuel for ships.  No fresh water is to be had, except by digging, the island being but a few feet above high-water mark.