| Depth in Yards. | Percentage. | Depth in Yards. | Percentage. |
|---|---|---|---|
| 160 | Nil | 270 | 21 |
| 170 | 3 | 280 | 23 |
| 180 | 5 | 290 | 24 |
| 190 | 8 | 300 | 25 |
| 200 | 10 | 350 | 30 |
| 210 | 12 | 400 | 35 |
| 220 | 14 | 450 | 40 |
| 230 | 15 | 500 | 45 |
| 240 | 16 | 550 | 50 |
| 250 | 17 | 600 | 55 |
| 260 | 19 | 650 and over | 60 |
The percentage at intermediate depths to be in proportion.