THE SOURCE OF THE NILE. 66; 



tity of vapour which is here driven foiuhward before the 

 Etefian winds. Novv,allthat country between Gerri and Syene 

 is flat and defert,fo that this interruption is wanting; and it is 

 owing to the famecaufe, that the bounds of the tropical rains 

 do flop farther to the fouthward as you travel weftward, and 

 in place of lat i6°, which is their limits at Gerri, they are con- 

 fined within lat. 14 in that part of the kingdom of Sennaar 

 which lies fouth and weft of that capital, where all is free 

 from mountains till you come to thofe of Kuara and Fa- 

 zuclo. 



Yet although the fun's influence when at its greateft, is 

 not ftrong enough to draw the boundaries of the fummer's 

 rain farther north than Gerri, all the time that it is in the 

 tropic of Cancer at its greateft diftance, thefe rains are then 

 at their heavieft throughout all Abyflinia ; and Egypt,andall 

 its labours, would foon be fweptinto the Mediterranean did 

 not the fun now begin to change its fphereof a&ion by ha- 

 ilening its progrefs fouthward. 



From Syene the fun pafles over the defert, and arrives at 

 Gerri'; here he reverfes the eflfe&s his influence had when 

 on his paflage northward ; for whereas, in his whole courfe 

 of declination northward, from the Line to Gerri, he brought 

 on the rains at every place where he became vertical, fo 

 now he cuts off thofe rains the inftant he returns to the 

 zenith of each of thofe places pafling over Abyflinia in his 

 journey fouthward, till arrived at the Line, in the autumnal 

 equinox, his influence ceafes on the fide of Abyflinia, and 

 goes to extend itfelf to the fouthern hemifphere. And fo 

 precifely is this ftupendous operation calculated, that, on 

 the 25th of September, only three days after the equinox,the 



4 p 2 Nik 



