ox THE CLIMATOLOGY OF AFRICA. 



OVO 



Victoria, Nyanza Lake Lei-eU and Rainfall, in Decadea. 

 Ohscrrcrs : F. Pordage, F. A. Xnowles, H. Gait, S. Spire, U'. Jt. Walker, 



and others. 



Xtebe, 

 1899 



Decades 





JIaioh, 



Januarv, I. 



„ " n. 

 III. 



l-eliniary, I. 

 II. 

 III. 

 I. 

 II. 

 III. 

 I. 



n. 



III. 



I. 



11. 



III. 



I. 



II. 



in. 



• lulV, 1. 



II. 

 III. 



August, I. 



ir. 

 III. 



September, I. 

 IT. 



April, 



Hay, 



Jiiue, 



• ■tuber, 



in. 



I. 



II. 



III. 



Xiivcmber, I. 



H. 



III. 



1 'ecembcr, I. 



II. 



HI. 



Lake 

 Level 



In. 



+ 3-00 



2-62 



2-G7 



3-67 



3-17 



2-66 



3Ut 



2-72 



2-47 



1-72 



1-82 



3-97 



3-64 



4-54 



4-22 



4-89 



4-42 



4-65 



4-97 



4-95 



3-61 



2-17 



+ 0-32 



-2-30 



-3-55 



-4-68 



-G-58 



-G-33 



-7-13 



-7-76 



-8-30 



-8-88 



-9-73 



-9-53 



-8-93 



-6-48 



Fort 



Tbrustou, 



189'J 



Lake 

 Level 



111. 



-0-7f) 



-1-U3 



-1-31 



-2-81 



-2-56 



-1-.S5 



-2-3« 



-2-98 



-3-5.'> 



-3-73 



-3-ti8 



-2-48 



-2-48 



+ ir32 



+ 3-22 



+ 2-17 



-U-2S 



-1-13 



-3MI8 



-2-73 



-2-93 



-8-23 



-12-48 



-13-49 



-lti-38 



-17-08 



-18-98 



-19-93 



-21-78 



-22-43 



Xtebe (F. Alice), 19u0 



Lake 

 Level 



In. 



-6-C8 

 -G-38 

 -G-12 

 -5-88 

 -5-38 



— 5-U3 

 -5-33 

 -5-03 

 -4-53 

 -5-63 



— 5-53 

 -5-53 

 -4-28 

 -5-03 

 -4-58 

 -4-28 



— 3-63 

 -3-43 

 -3-03 

 -2-53 

 -2-15 

 -2-78 

 -3-23 

 -4-12 

 -5-83 

 -7-53 



-10-23 

 -13-33 

 -15-93 

 -17-21 

 -18-08 

 -18-73 

 -19-53 

 -18-98 

 -18-08 

 — 16-53 



Fort 

 Tlirustou 

 (Lubwas) 



Lake 

 Level, 



1900 



Kisumn, 



on Kavi- 



rondo or 



Njjowe 



Bay. Lake 



Level, 



1900 



In. 



-19-18 

 -18-98 

 -18-53 

 -18-83 

 -18-88 

 -18-80 

 -18-78 

 -18-73 

 -19-08 

 -20-43 

 -21-13 

 -23 43 

 -25-28 

 — 26-78 

 -29-21 

 -30-18 

 -30-13 

 -30-63 

 -28-43 

 -27-f:8 

 -23-03 



In. 



- 5-30 



- 5-85 



- 6-45 



- 7-80 



- 8-20 



- 4-67 



- 7-80 



- 8-20 



- 4-67 



- 5-10 



- 5-50 



- 3-90 

 + 0-75 



- 2-35 



- 2-94 



- 2-50 



- 1-50 



- 3-75 



- 5-50 



- 6-90 



- 7-76 



- 6-97 



- 7-90 

 -12-57 



- 10-10 

 -10-65 



- 6-30 

 -1.5-05 

 -lfi-20 

 -16-75 

 -17-60 

 -16-45 



- 16-90 

 -15-97 

 -14-60 

 -11-48 



There can be no doubt 

 that tlie lake level is pri- 

 marily influenced by the 

 rainfall. At Ntebe the 

 level rose ia the course 

 of 1898 (which was a 

 year cf abundant rains), 

 but in the course of 1899 

 it fell slightly below the 

 level of 1896, and in 1900 

 it fell a further 7-62 

 inches. As that year 

 (19U0) was one of fairly 

 abundant rains along the 

 Buganda shore (61 inches 

 fell at Ntebe) we are 

 bound to assume that it 

 is not local r.iius whicli 

 appreciably affect the 

 level of the lake, but the 

 precipitation throughoiat 

 its vast drainage area. 

 Tims an abundant rain- 

 fall along the Buganda 

 shore would be neutral- 

 is-ed by a deficiency in 

 the rainfall in the south. 



Since the beginning of 



tlie present year (1901) 

 ilie lake has risen rapidly, and by June 1 its level stood 24 inches above the mean level of 1896. The relations between 

 local rainfall and lake level are illustrated bv the following facts :— 



At Xtebe, between March 20-24, 1900, 3-7 inclies of rain fell, and in the course of April 13-54 inches, yet the level of the 

 lake remained unaffected, tlie lieavy local rains being balanced by the outflow and tlie loss by evaporation, or deficiency 

 of rain elsewhere. Yet in tlie course of May the lake rose slowly, but steadily, although very little rain was registered 

 locally. Again, between December 3-5 4-21 inches of rain fell, while the lake onlv rose half an inch. More remarkable still, 

 on September 12 1-25 inches of rain fen,yet the lake level actually fell half an inch.' The other stations afford similar instances. 

 The winds exercise a decided iiifltience upon the level of the lake. There are regular land and lake breezes, and 

 Mr. Macallister remarks that a strong S.W. breeze will cause a rise in the level of the lake to an extent of from 

 1 to 3 inches. At Fort Tliruston, on Xovember 13, a severe storm caused the lake to rise 3 inches. The influence of the 

 w-ind could be eliminated by making at least three observations daily, and which would be preferable, by establishing a 

 self-registering gauge. Further fluctuaticns of the lake may be produced by differences of barometric pressure. 



The difference between the highest and lowest level at Xtebe amounted to 19-0 inches in 1896, 16-5 inches in 1899, and 

 17-50 inches in 1900. The extreme range, as far as our observations extend, has been 43-5 inches ; but if the level, in 1881, 

 exceeded that of 1898 to the extent of 8 feet, as asserted by the French missionaries in Buganda, its amount cannot be less 

 tlian 10 feet. 



All observations made at Xtebe and Fort Thruston (Lubwa's) are referred to the mean lake level at those stations in 

 1896. On October 1898 Mr. G. W. Fowler, Superintendent of Marine, claims to have adjusteil ail gauges to Port Victoria (where 

 observations ?cased to be made at the end of July 1899). I fail to see how- this can have been done unless the three stations 

 were joined by a line of spirit levelling. On comparing the observations made between October 1898 and February 1899, 

 as recorded, I find that, assuming the level at Port Victoria to be —0-00, the level at Ntebe exceeded that datum level to 

 the extent of 1-98 inches, whilst that at Fort Thruston fell short of it to the extent of 1-89 inches. Such differences in the 

 level may exist, though I fail tii see how they can have been ascertained. From all observations reconled since October 1898, 

 3fi-53 inches have been deducted in order to reduce them approximately to the mean lake level of 189G. In the case of Kisumu, 

 however, only 30-3 inches have been deducted. 



a 



o 



Jan. 



Feb. 



Mar. 



Apr. 



May 



Juu. 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Deo. 



Tear 



Xtebe. Rain, 1900 



§ 



a 



In. 



2-26 

 4-23 

 6-10 



13-54 

 2-70 

 5-81 

 0-43 

 2-90 

 3-43 

 1-53 

 5-99 



12-51 



61-43 



No. 



8 

 12 

 14 

 20 

 13 

 12 



4 



6 



9 

 11 

 16 

 13 



138 





In. 



0-72 

 2-50 

 1-39 

 1-96 

 0-93 

 2-82 

 0-28 

 1-25 

 1-51 

 0-78 

 1-36 

 2-10 



2-82 



