NARRATIVE OF THE CRUISE. 
779 
distances apart, previously calculated angles were used, whereas to fix the position of 
previously agreed upon depths, it became necessary to observe independent angles. In 
this manner all the lines of soundings were run to such a depth as was possible in a boat, 
the coast line of the reef was sketched in, and the ship afterwards extended the lines to 
a distance of 2055 fathoms from the reef.” 
The results of these observations are given in the diagrams and following table (see 
Sheet 39 and figs. 269-271). 
Comparative Table of the Six Sections of the Outer Edge of the Barrier Reef at Tahiti. 
Distance 
from Edge 
of Beef in 
Fathoms. 
Xo. 1 Section. 
Xo. 2 Section. 
Xo. 3 Section. 
Xo. 4 Section. 
Xo. 5 Section. 
Xo. 6 Section. 
Depth in 
Faths. 
Angle of 
Slope. 
Depth in Angle of 
Faths. j Slope. 
Depth in 
Faths. 
Angle of 
Slope. 
Depth in 
Faths. 
Angle of 
Slope. 
Depth in 
Faths. 
Angle of 
Slope. 
Depth in 
Faths. 
Angle of 
Slope. 
0 
10 
12 
°2 
17 
°5 
2 
°5 
15 
2 
17 
3 
26 
25 
4-5 
12 
24 
1-0 
2 
45 
2-2 
11 
58 
2-3 
7 
58 
1-0 
2 
45 
1-5 
4 
7 
50 
10-0 
12 
51 
2-2 
21 
24 
7-5 
17 
45 
5-8 
15 
0 
2-2 
23 
22 
3-3 
15 
0 
75 
157 
16 
54 
12-0 
17 
45 
15-5 
16 
42 
12-5 
26 
34 
13-0 
15 
38 
10-0 
15 
38 
100 
23-0 
17 
45 
20-0 
25 
38 
22-0 
27 
28 
25-0 
54 
28 
20-0 
37 
14 
17-0 
13 
30 
125 
31'0 
43 
14 
32-0 
68 
40 
35-0 
66 
19 
60-0 
59 
14 
39-0 
69 
15 
23-0 
4 
34 
150 
54-5 
66 
8 
96-0 
37 
14 
92-0 
38 
39 
102-0 
15 
38 
105-0 
38 
39 
25-0 
72 
39 
175 
111-0 
51 
44 
115-0 
30 
58 
112-0 
35 
45 
95-0 
60 
57 
125-0 
45 
0 
105-0 
38 
39 
200 
142-7 
130-0 
37 
14 
130-0 
41 
21 
140-0 
55 
13 
150-0 
30 
58 
125-0 
50 
12 
225 
149-0 
32 
37 
152-0 
6 
50 
176-0 
13 
30 
165-0 
30 
58 
155-0 
45 
0 
250 
165"0 
155-0 
170-0 
180-0 
180-0 
An examination of these sections shows that a depth of 25 to 35 fathoms is met with 
at 100 to 150 fathoms from the edge of the reef. At about this distance from the reef 
there is a rapid increase of depth to 160 and 180 fathoms, these latter depths being met 
with at a distance of 225 to 250 fathoms from the edge of the reef. Between the depths 
of 35 and 100 fathoms the average slope is about 45°. The slope is about 30° to 200 
fathoms or thereabouts, and then becomes less and less until a slope of 6° is met with half a 
mile from the reef. The whole of the space from the edge of the reef to a depth of 35 
fathoms was covered with a most luxuriant growth of corals, with the exception of one or two 
small spaces where there was white coral sand. The depths were most irregular, the sound- 
ing lead at one time falling on a coral boss, and showing a depth of 5 or 6 fathoms, and 
then close alongside it a depth of 16 fathoms. It could be seen with the water glass 
that many of these bosses and heads of coral were overhanging and in a most luxuriant 
