A Contribution to the Study of the Diamond Made. 159 
sions to wliicli macles also tend to conform. Clearly there is no hard and 
fast necessity that a made should be tabular seeing that now and then one 
comes across a made which is made up exactly of two halves of a regular 
octahedron ; but it is a question whether such a one is to be regarded as 
representing a standard from which all others are departures or whether it 
is itself a departure from whatever the standard may be. If it be the 
standard, then although the average spread (i. e. the ratio of length of edge 
to thickness) of all together may be much greater than its own, yet the 
actual numbers of the thinnest ones (ratio large) will be less than the 
actual numbers of the thickest ones (ratio small). 
With the object of determining, first, the average spread, and, second, 
whether that average signifies a standard dimensional ratio or is merely 
a numerical median value, measurements of diamond macles of good 
geometrical symmetry have been made as opportunity offered. The results 
are set forth in the tables below. 
Table 1. — Octahedral Macles. 
Mine. 
Edge shorter than 5 mm. 
Edge from 5 to 7*9 mm. 
Edge 8 mm. and longer. 
No. 
Average 
edge. 
Spread 
E/T. 
No. 
Average 
edge. 
Spread 
E/T. 
No. 
Average 
edge. 
Spread 
E/T. 
Koffyfontein . 
Jagersfontein . 
Dutoitspan 
Bultfontein 
Wesselton 
8 
1 
3 
50 
9 
mm. 
3- 4 
4- 5 
4-1 
3-6 
3-6 
2-28 
1- 64 
304 
2- 74 
2-86 
4 
5 
10 
40 
27 
mm. 
6-3 
6-4 
6-5 
6-5 
6-6 
2-38 
2-15 
2-55 
2-82 
266 
1 
3 
6 
]5 
31 
mm. 
8- 2 
13-7 
13-5 
9- 3 
9-9 
3-73 
1- 82 
2- 55 
2-49 
2-57 
Total 
71 
3 6 
2-70 
86 
6-5 
2-68 
56 
]0-3 
2-53 
Table 2. — Bhombic-dodecahedral Macles. 
Mine. 
Edge shorter than 5 mm. 
Edge from 5 to 7"9 mm. 
Edge 8 mm. and longer. 
No. 
Average 
edge. 
Spread 
E/T. 
No. 
Average 
edge. 
Spread 
E/T. 
No. 
Average 
edge. 
Spread 
E/T. 
Koffyfontein . 
Jagersfontein . 
Dntoitspan 
Bultfontein 
Wesselton 
8 
4 
3 
25 
23 
mm. 
4-3 
4-4 
3-8 
3-4 
3-8 
2-16 
2-15 
1- 85 
2- 06 
2-32 
6 
9 
7 
36 
30 
mm, 
6-0 
6-8 
6-5 
6-2 
6-4 
2-68 
2-44 
2-23 
2-30 
2-42 
6 
6 
3 
13 
mm. 
9-6 
12-4 
8- 9 
9- 3 
2-33 
1-99 
1- 97 
2- 50 
Total 
63 
3-7 
2-18 
88 
6-3 
2-38 
28 
100 
2-30 
Table 1 gives, for five mines, particulars of the ratio of length of edge 
(E) to thickness (T) of macles of prevailingly octahedral character, arranged 
in three sets according to length of edge. 
