Investigator's Strait.] TERRA AUSTRALIS. 175 
Wedge I. (of Gambier's Isles), highest part, - N. W. I802. 
Althorpe Isle, largest, distant 6 miles, - N. 83 0 to 78 W. TbEk 
Cape Spencer, south point, - - N. 44 W. 
Furthest extreme of the northern land, - 4 N. 44 E. 
The wind fixed itself at south-east, and it took us two days to 
work back against it as far as Troubridge Hill. The shore is Saturdays?, 
generally low and sandy ; but with the exception of one very low 
point, it may be approached within two miles. Many tacks were 
made in these two days, from the northern land across to Kanguroo 
Island, and gave opportunities of sounding the intermediate strait. 
From 45 fathoms, in the middle of the western entrance, the depth 
diminishes quickly to 25, then more slowly to 20; after which it 
is irregular between 12 and 20 fathoms, as far as the mouth of 
the second inlet. Of the two sides, that of Kanguroo Island 
is much the deepest; but there is no danger in any part to pre- 
vent a ship passing through the strait with perfect confidence ; and 
the average width is twenty-three miles. It was named Investi- 
gator's Strait, after the ship. The bottom is mostly broken shells, 
mixed with sand, gravel, or coral, and appeared to hola well. 
From two amplitudes taken to the north-nortn-west of Point 
Marsden, and near the middle of the strait, the variation was i° 49' 
east ; the ship's head being south-south-east in one case, and north- 
east-by-north in the other. The true variation deduced from these, 
is 3 0 20' east; which is i° 7' greater than at Cape Spencer, and o° 53' 
less than at the anchorage near Kanguroo Head. 
At noon of the 27th, the eastern wind died away ; and we 
dropped a kedge anchor in 15 fathoms, about two miles from Point 
Marsden, where the following observations and bearings were taken. 
Latitude, observed to the north, - 35 0 31' 38" 
Longitude by time keepers, - - 137 42 
Kanguroo I., furthest western extreme, - S. 82 W. 
Point Marsden, west side, - S. 26 W. 
, innermost head up Nepean Bay, S. 27 E. 
furthest eastern extreme, - S. 57! E. 
Cape Jervis, south extreme, - - S. 73 E. 
