The astronomers took up their abode in the huts, which were quickly appropriated for the use of their new occupants. Their requirements were but small; their one thought was directed towards verifying their calculations by measuring the last side of their last triangle.
The astronomers at once proceeded to their work. The trestles and platinum rods were arranged with all the care that had been applied to the earliest base. Nothing was neglected; all the conditions of the atmosphere, and the variations of the thermometer, were taken into account, and the Commission, without flagging, brought every energy to bear upon their final operation.
The work, which lasted for five weeks, was completed on the 15th of May. When the lengths obtained had been estimated and reduced to the mean level of the sea at the temperature of 61° Fahrenheit, Palander and Emery presented to their colleagues the following numbers:—
| Toises. | |
| New base actually measured | 5075.25 |
| The same base deduced trigonometrically from the entire series | 5075.11 |
| ——— | |
| Difference between the calculation and the observation | 0.14 |
Thus there was only a difference of less than 1/6 of a toise that is to say, less than ten inches; yet the first base and the last were six hundred miles apart.
When the meridian of France was measured from Dunkirk to Perpignan, the difference between the base at Melun and that at Perpignan was eleven inches. The agreement obtained by the Anglo-Russian Commission was still more remarkable, and thus made the work accomplished in the deserts of Africa, amid dangers of every kind, more perfect than any previous geodetic operation.
The accuracy of this unprecedented result was greeted by the astronomers with repeated cheers.
According to Palander's reductions, the value of a degree in this part of the world was 57037 toises. This was within a toise, the same as was found by Lacaille at the Cape in 1752: thus, at the interval of a century, the French astronomer and the members of the Anglo-Russian Commission had arrived at almost exactly the same result. To deduce the value of the mètre, they would have to wait the issue of the operations which were to be afterwards undertaken in the northern hemisphere. This value was to be the 1/10000000 of the quadrant of the terrestrial meridian. According to previous calculations, the quadrant, taking the depression of the earth into account, comprised 10,000,856 mètres, which brought the exact length of the mètre to .013074 of a toise, or 3 feet 0 inches 11.296 lines. Whether this was correct the subsequent labours of the Commission would have to decide.
The astronomers had now entirely finished their task, and it only remained for them to reach the mouth of the Zambesi, by following inversely the route afterwards taken by Dr. Livingstone in his second voyage from 1858 to 1864.