To me these observations were more than usually interesting, as when I had met my friend Speke at Gondokoro he was much perplexed concerning the extraordinary difference in his observation between the altitude of the river level at Karuma Falls, lat. 2 degrees 15', and at Gebel Kookoo in the Madi country, lat. 3 degrees 34', the point at which he subsequently met the river. He KNEW that both rivers were the Nile, as he bad been told this by the natives; the one, before it had joined the Albert lake—the other, after its exit; but he had been told that the river was NAVIGABLE from Gebel Kookoo, lat. 3 degrees 34', straight up to the junction of the lake; thus, there could be no great difference in altitude between the lake and the Nile where he met it, in lat. 3 degrees 34'. Nevertheless, he found so enormous a difference in his observations between the river at Karuma and at Gebel Kookoo, that he concluded there must be a fall between Karuma and the Albert lake of at least 1,000 feet; by careful measurements I proved the closeness of his reasoning and observation, by finding a fall of only 275 feet more than he had anticipated. From Karuma to the Albert lake (although unvisited by Speke), he had marked upon his map, "river falls 1,000 feet;" by actual measurement I proved it to be 1,275 feet.
The altitudes measured by me have been examined, and the thermometer that I used had been tested at Kew, and its errors corrected since my return to England; thus all altitudes observed with that thermometer should be correct, as the results, after correction by Mr. Dunkin, of the Greenwich Royal Observatory, are those now quoted. It will therefore be interesting to compare the observations taken at the various points on the Nile and Albert lake in the countries of Unyoro and Chopi—the correctness of which relatively will be seen by comparison:—
1861.
Jan. 22. Rionga's island, 80 feet above the Nile . . . 3,864
Jan. 25. Karuma, below the falls, river level Atadaj. . 3,996
Jan. 31. South of Karuma, river level on road to M'rooli 4,056
1864.
Feb. 21. M'rooli lat. 1 degree 38' river level . . . . . . 4,061Ft.
Mar. 14. Albert N'yanza, lake level . . . . . . . . . . . 2,720Ft.
April 7. Island of Patooan (Shooa Moru) river level. . . . 3,195Ft.
By these observations it will be seen that from M'rooli, in lat. 1 degree 38' to Karuma in lat. 2 degree 15', there is a fall of sixty- five feet; say MINUS five feet, for the Karuma Falls equals sixty feet fall in 37' of latitude; or allowing for the great bend of the river, twenty miles of extra course, it will be equal to about sixty statute miles of actual river from M'rooli to Atada or Karuma Falls, showing a fall or one foot per mile. From M'rooli to the head of the Karuma Falls the river is navigable; thus the observations of altitudes showing a fall of one foot per mile must be extremely accurate.
The next observations to be compared are those from Karuma Falls throughout the westerly course of the river to the Albert lake:—
River level below Karuma Falls . . . . . . . . 3,996 feet
Rionga's island 3,864—80 feet cliff . . . . . 3,784
= 212 fall. to the west.
River level at island of Patooan (Shooa Moru). 3,195
= 589 fall. from Rionga's island.
Level of Albert lake . . . . . . . . . . . . . 2,720
= 475 fall. from Patooan to lake.
From Karuma . . . . . . . . . . . . . . . . . 1,276 fall.
These observations were extremely satisfactory, and showed that the thermometer (Casella's) behaved well at every boiling, as there was no confusion of altitudes, but each observation corroborated the preceding. The latitude of the island of Patooan by observation was 2 degrees 16': we were thus due west of Magungo, and east of Karuma Falls.