KHARTUM 
405 
seemed to make no progress, and a tree more prominent than the 
rest seemed as far off as ever. As I gazed at the distant trees some¬ 
what wistfully they seemed to rise slowly into the air, and the river 
itself came into view. Slowly and imperceptibly the water spread 
itself out over the sand, until I seemed to be walking towards a lake 
whose surface was strangely unruffled, in spite of the strong north 
wind sweeping over the desert. I glanced to the left and was 
confronted by the same appearance of a vast inundation. Turning 
round I found that the same sheet of water had cut me off from the 
domes and palms of Khartum, The rising river seemed both to bar 
my advance and to have cut off my retreat—there appeared to be water 
on three sides of me ! Had I not seen many a mirage before, I feel 
sure that I should have turned and fled in terror towards the desert, 
and even as it was, I found it difficult to overcome a certain nervous¬ 
ness as I pursued my way. However, gradually as the acacia trees 
drew nearer and nearer, the inundation began to retreat, so that 
when I at last stood upon the bank, there was the Blue Kile flowing 
steadily many feet below the level of the arid desert. 
Any description of Khartum would be inadequate if it did not 
allude to the prevailing northerly wind, which is not only health¬ 
giving, but entomologically speaking most important. Mr. A. L. 
Butler, the Curator of the Zoological Gardens, informed me that 
there is no continuous rainy season, but that heavy tropical downfalls 
are frequent in June, July, and August. 
Khartum is not altogether a pleasant place for the collector. To 
the south is a specially barren 1 and wind-swept desert; the northern 
bank of the river is abandoned to barracks, railway works and dock¬ 
yard-—for Khartum is a naval port with a fleet of gunboats—hence 
my operations were practically confined to the neighbourhood of 
the river bank above and below the city. Of the two localities, the 
best, though the most distant, was beyond the water-works, near the 
terminus of the tramway in the village of Burri. Here, among 
Calotropis procera, the wide-ranging Danaida chrysippus was 
common, and I was delighted to see alive for the first time the form 
alcippus, Cram. The white hind-wings of these beautiful butter¬ 
flies are conspicuous in flight, and at once reminded me of the yet 
more beautiful Acrctea, alboradiata, Auriv., which I had seen in such 
numbers at the Victoria Falls four years before. From Cairo ot 
Aswan I had come across a fair number of chrysippus, but all of the 
typical form. At Abu Simbel, in Nubia, I was surprised not to meet 
1 Actually barren: potentially it is said to be fertile, a thin coating of sand 
covering a deep deposit of silt. 
