29th, p.m.—A hollow, with water:—
| Borrow | 101 | |||||
| Trocheameter | 76 | 53 | ||||
| 50 | 73 | |||||
| 25 | 81 | |||||
| m. | fur. | yds. | ft. | in. | ||
| 20 | 5 | 6 | 120 | 0 | 10 | |
| 5 | 1 | 3 | 14 | 0 | 2½ | |
| 81 | 0 | 1 | 190 | 1 | 10½ | |
| 7 | 3 | 104 | 0 | 11 | ||
30th.—A small Vlei:—
| Borrow | 101 | |||||
| Trocheameter | 93 | 44 | ||||
| 76 | 53 | |||||
| 16 | 92 | |||||
| m. | fur. | yds. | ft. | in. | ||
| 10 | 2 | 7 | 60 | 0 | 5 | |
| 6 | 1 | 5 | 212 | 0 | 3 | |
| 92 | 0 | 2 | 26 | 1 | 2 | |
| 4 | 7 | 78 | 0 | 10 | ||
31st.—Outspan in the Bush.
| Trocheameter | 12 | 89 | ||||
| Add | 100 | |||||
| 112 | 89 | |||||
| 93 | 44 | |||||
| m. | fur. | yds. | ft. | in. | ||
| 10 | 2 | 7 | 60 | 0 | 5 | |
| 9 | 2 | 4 | 208 | 0 | 4½ | |
| 45 | 0 | 1 | 8 | 0 | 4½ | |
| 5 | 5 | 56 | 1 | 2 | ||
As a means of measuring a base line for triangulation of a country the trocheameter is invaluable. Suppose the course is north, and that a mountain bears 90°, or east; let the waggon travel till the mountain bears 45° more southerly, or 135°, i.e., south-east; then stop the waggon, read the trocheameter, and the length of road travelled will be equal to the distance of the mountain from the starting place. Even if the course does not form a right angle with the bearing, the same method may be followed, involving only a little more calculation, or the trouble of laying down the angle upon paper. In places where a waggon cannot travel, it would be well to have a large wheel, on the principle of the old perambulator, and fix the trocheameter upon it; only let it be loaded, so as to bear the semblance of usefulness in the eyes of natives, or even of illiterate white men, or they will infallibly carry it over the bad places, as Captain Sturt’s men did, to save themselves trouble. The trocheameter may be fitted to any piece of machinery, as the screw or paddles of a steamer, the sails of a windmill, a waterwheel, or anything capable of turning round.
To ascertain the Variation of the Compass.
