many varieties of fish, the most abundant being snappers;
of those that were rare Lieutenant Emery made faithful sketches.

(*Footnote. Haemapodicus scintilans, Gould.)

Half a mile west from Slaughter Point we found two caverns similar to
that on East Wallaby Island, from which we got three tons of excellent
water.

APPEARANCE OF THE REEFS.

The reefs surrounding this group appeared very much broken; and even at
Easter Group we had found them to be not so regular as at Pelsart's. This
suggests the idea, which appears to be borne out by all we saw, that the
reefs are compact in proportion to the exposed position of the islands;
the shelter afforded by Pelsart Group, in fact, did not require the reefs
to be so united round the other islands to the north.

From the highest part of East Wallaby Island we discovered a patch of
land bearing North-West 1/2 North eleven miles. The outer reef extended
in that direction from the south-west point of West Wallaby Island,
though it could only be traced by detached patches of breakers. To the
south-east of its commencement lies Evening Reef. The observations were
made on the north end of the north-east Pigeon Island, bearing West by
South half a mile from our anchorage, in latitude 32 degrees 27 minutes
21 seconds South and longitude 2 degrees 1 minute 10 seconds West of Swan
River, variation 4 degrees 10 minutes westerly. The temperature of
Houtman's Abrolhos is rendered equable by the fact that they lie at the
limit of the land breezes; during the month we were there the thermometer
averaged 71 degrees.

Our protracted stay enabled us to get a tolerable series of tidal
observations, which present some singular results. The time of high-water
at the full and change was six o'clock when the tide rose 30 inches. It
appeared that during the night there was a short flood of six hours with
a rise of seven inches, and an ebb of two hours with a fall of only five
inches; but that during the day the flow and ebb were nearly equal, the
former being eight hours and twenty minutes, the latter eight hours and
five minutes, and the rise and fall in each being 25 and 26 inches
respectively.

TIDAL OBSERVATIONS.

A difference was also noticed between the day and night tides at Rat
Island, where the time of high-water at the full and change of the moon
was ten o'clock, and the rise varied from 8 to 32 inches, from the result
of twenty-five observations; by which I found, moreover, that t