February 12, 1920] 



NATURE 



633 



when I point out that the chief difficulty in the 

 way to complete success on the part of aviation 

 is the coming- down safely from the air to the 

 solid earth. No air pilot can view without grave 

 apprehension a forced descent on an uneven or 

 merely a slightly irregular surface. The pas- 

 sengers might not be more than shaken or bruised, 

 but the delicate machine might be so injured as 

 to be unable to resume its flight. But for this 

 trouble about desc-ent and ascent, the exploration 

 of the world's land surface would now be pro- 

 ceeding at a tremendous rate. Soon the whole 

 of the continents and islands would be made known 

 in all their details. 



I have always hoped myself that there may be 

 some wonderful development in mechanics or in 

 physics by which heavier-than-air machines might 

 be enabled (i) to rise direct from the ground 

 into the air vertically ; and (2) to descend vertically 

 and slowly, under control, making use of air- 

 brakes in some way. The latter process may read 

 as an impossibility, but it is not more improbable 

 than many a feat in aviation would have sounded 

 to the scientific theorist twenty years ago. 



Then, again, I am sure we have neglected 

 another safety apparatus : the devising of cloth- 

 ing that might be so inflated with air that the 

 wearer would float to earth as gently as thistle- 

 down. 



The original mind of Dr. Chalmers Mitchell may 

 well come back from his great air journey with 

 new conceptions as to the future solution of these 

 and other difficulties in aviation. F"ew people 

 know as much as he does about bird-structure, and 

 he may, when he is "up against it," be inspired 

 to apply to the theory and practice of aviation 

 some bright ideas — as yet overlooked — to be 

 derived from the bird's development of the art of 

 flying, especially the efforts made by heavy birds 

 (cranes, storks, swans, peafowl, bustards, and 

 large vultures) to rise into the air, to maintain 

 themselves resting (floating) in the air, and to 

 descend from a great height to the ground 

 uninjured. 



As to Dr. Mitchell's experiences and those of his 

 companions on this actual journey, my impressions 

 are : that by rising to eight or nine thousand feet 

 they will ascend above the dangerous storms or 

 violent winds of Central Africa ; that they will 

 nowhere run any serious danger from wild or 

 savage men, except among the Dinkas of the 

 Nile Valley (east of the Bahr-al-Ghazal) ; that they 

 have very little to fear from any wild beast except 

 a chance rhinoceros in East Africa ; and that in 

 seeing the desert yield to the Nile marsh-lakes, 

 the marshes give place to mountains — even snow- 

 mountains — and grandiose forest, the forest thin- 

 ning out into parklands, the parklands passing into 

 steppe, the steppe into desert, and the desert into 

 the cornfields, orchards, vineyards, and gardens of 

 South Africa, they will have had an unforgettable 

 lesson in physical geography. I wish them the 

 most complete success and a happy return. 



H. H. Johnston. 

 NO. 2624, VOL. 104] 



(2) Scientific Aspects of the Route. 



The expedition which started from Cairo on 

 February 6 should be memorable as the first 

 use of long-distance aeroplane flight for scientific 

 and geographical research. Thanks to the enter- 

 prise of the Times, a Vickers' " Vimy " aeroplane 

 is traversing Africa from Eg^pt to the Cape, with 

 Dr. Chalmers Mitchell as scientific observer and 

 Capts. Cockerell and Broome as pilots. The ex- 

 pedition will test the value of long aerial journeys 

 for scientific purposes, and as it is under a man 

 of such width of knowledge and scientific imagina- 

 tion as Dr. Chalmers Mitchell, we may be con- 

 fident that the opportunity will be used to the best 

 advantage. 



The expedition is to travel leisurely, at moderate 

 elevations, and never flying at night, so as to 

 enable Dr. Chalmers Mitchell to obtain a clear 

 survey of the country traversed. The route is 

 from the aerodrome at Heliopolis, near Cairo, up 

 the Nile, past Assuan, to Wadi Haifa, and thence, 

 along the railway line, across the Dongola bend 

 of the Nile, to the river again past Atbara to 

 Khartum ; then up the White Nile past Mongalla 

 and Gondokoro and over the Nile rapids to 

 Nimule. Thence the most direct route would be 

 to leave the river and cross the Fatiko country to 

 Lake Kiogo, and there rejoin the Nile, following 

 it to its outflow from the Victoria Nyanza at the 

 Ripon Falls. The expedition will fly over the lake 

 to Kisumu, at the end of the Uganda Railway, 

 skirt the irregular eastern coastlands to Mwanza, 

 on the southern shore of the Victoria Nyanza, 

 and cross " German " East Africa to Abercorn at 

 the southern end of Tanganyika. Thence the route 

 will be above north-eastern Rhodesia to the mining 

 fields of the African Broken Hill, and along the 

 railway past the Victoria Falls on the Zambezi to 

 Wankie coalfield and Bulawayo ; it will continue in 

 sight of the railway another 182 miles southward 

 to Palapye, where it will bend eastward across 

 the northern Transvaal to Pretoria, and by follow- 

 ing the railway past Johannesburg, Bloemfontein, 

 and Beaufort West end its journey, of 5206 miles 

 by the route projected, at Cape Town. 



This journey must naturally be direct, long dis- 

 tances must be covered daily, and deviations to 

 follow up interesting clues may be inadmissible, 

 for the main object of this flight is to demonstrate 

 the practicability of the aeroplane in the next stage 

 of African research and development. The pros- 

 pects are promising, for a bird's-eye view from a 

 moderate elevation would reveal much of interest 

 and practical value regarding the geography, 

 geology, and botany of those parts of Africa com- 

 posed of arid plains like the Fast African Nyika. 

 One difficulty with their investigation is that, 

 owing to the covering of scrub, travellers by foot 

 or on horseback may march for days and see 

 nothing beyond a few hundred yards beside the 

 route, while any useful plahe table survey is im-" 

 possible. A view from above would, however, 

 show all the essential features ; the valuable areas 

 are on the volcanic rocks or on limestones, both 



