A close-grained sand stone, nearly resembling that of Pellew's Group, seems to form the basis of Groote and the neighbouring islands; we found also coral, ironstone, and quartz. In many places, quartz in almost a crystallised state was sprinkled in grains through the sand stone, and in others, the sand stone itself was partly vitrified. Wherever we landed, the surface was so entirely composed of stone and sand, that the idea of any kind of cultivation could in no wise be assimilated with it; the hills at a little distance from the water side were, however, well covered with wood, and it is not improbable, that there may be vallies in the central parts of Groote Eylandt possessing some degree of fertility. The central hill, which is six or eight hundred feet in elevation, appeared to be not so much as three leagues from the head of North-west Bay, and I was desirous to have made an excursion to the top, to see the interior of the island; but the state of the ship being such as to press us forward with all practicable haste, it was not attempted; nor did I stop to examine particularly the head of the bay, since it appeared to be shallow, and of little interest to navigation.
The wood on Groote Eylandt was mostly composed of different species of eucalyptus; the trees were small, and might do for fire wood and very common purposes, but did not seem calculated for any superior use. Chasm Island was the sole place where the nutmeg was found, though in general, the gleanings of the botanists were tolerably fortunate. None of the native inhabitants were seen, nor any kangaroos or other quadrupeds; and birds seemed to be scarce. Small quantities of water, deposited in holes of the rocks by the late rains, were useful to the seamen for washing their clothes; but we did not find any from which a ship could be supplied, nor were there any beaches convenient for hauling the seine.
The latitude of Finch's Island, from a meridian observation to the north and south, is 14° 43' 31" S.
Longitude from six sets of distances of the sun east of the moon, taken by myself, 136° 38' 47", and from twelve sets by lieutenant Flinders (see Table V. of Appendix No. I), 136° 23' 38"; but there being no observations of the moon at Greenwich within two or three days, the longitude from survey and the position of Caledon Bay afterwards fixed, is preferred, and is 136° 36' 53" E.
Dip of the south end of the needle, 39° 22'.
Variation of the theodolite, 3° 6' east.
The variations of the surveying compass, from amplitudes taken near different parts of Groote Eylandt during the circumnavigation, were these:--
Near the main, opp. the S.W. Pt., head E. by S., 0° 43', cor. 2° 44' E.
Near the south-west point, S. E., 1 9 , cor. 2 36
Off the east side, N. E. by N., 2 57 , cor. 4 4
Near the north-east isles., N. W. by W., 3 33 , cor. 1 58
Off the north end, S. W. by W., 5 51 , cor. 4 14
Whether the small variation near the north-east isles arose from any peculiar attraction, or from some oversight in taking the amplitude, I cannot determine; if from the latter, it would appear that the variation is a degree and a half less on the south-west, than on the east and north sides of Groote Eylandt.
Scarcely any run of tide was perceptible in North-west Bay, nor did the rise appear to exceed four or five feet at any part of the island, though it runs with some strength off the projecting points. The irregularity in different places was such, that the time of high water could not be ascertained; but I think there is only one full tide in the day, and that the flood comes from the northward.