I02 



NATURE 



{Dec. 3, 1880 



one of the characters of this yolk is ' all-alikeness,' you 

 at once perceive how nonsensical is their statement. You 

 see that the substance of the yolk is not all-alike, and 

 that therefore all-alikeness cannot be one of its attributes. 

 .Similarly with the other pretentious tenn ' heterogeneity,' 

 which, according to them, describes the state things are 

 brought to by what they call evolution. It is mere empty 

 sound, as is manifest if I do but transform it, as I did 

 the other, and say instead ' not-all-alikeness.' For on 

 showing you this chick into which the yolk of the egg 

 turns, you will see that 'not-all-alikeness' is a character 

 which cannot be claimed for it. How can any one say 

 that the parts of the chick are not-all-alike? Again, in 

 their blatant language we are told that evolution is carried 

 on by continuous ' differentiations' ; and they would have 

 us believe that this word expresses some fact. But if we 

 put instead of it 'somethingelseincations' the delusion 

 they try to practise on us becomes clear. How can they 

 say that while the parts ha-\-e beenforming themselves the 

 heart has been becoming something else than the stomach, 

 and the leg something else than the wing, and the head 

 something else than the tail ? The like manifestly happens 

 when for 'integrations' we read 'sticktogetherations' : 

 what sense the term might seem to have, becomes obvious 

 nonsense when the substituted word is used. For nobody 

 dares assert that the parts of the chick stick together any 

 more tlian do the parts of the yolk. I need hardly show 

 you that now when I take a portion of the yolk between 

 my fingers and pull, and now when 1 take any part of the 

 chick, as the leg, and pull, the first resists just as much 

 as the last — the last does not stick together any more than 

 the first ; so that there has been no progress in ' stick- 

 togetherations.' And thus, gentlemen, you perceive that 

 these big words which, to the disgrace of the Royal 

 Society, appear even in papers published by it, are mere 

 empty bladders which these would-be philosophers use to 

 buoy up their ridiculous doctrines." 



But though it is here, I think, made apparent enough 

 that even when disguised in Mr. Kirkman's grotesque 

 words, the definition of Evolution continues truly to ex- 

 press the facts. Prof Tait shows no sign of changing his 

 original opinion that Mr. Kirkman has made "an ex- 

 quisite translation " of the definition. Nay, so charmed 

 does he appear to be with Mr. Kirkman's feats of this 

 nature, that he gives us another of them. One of two 

 conclusions must be drawn. Prof. Tait either thinks 

 that fallacies are disclosed by the aid of these cacophonous 

 long words, or else the clatter of curious syllabic compounds 

 greatly excites his sense of liumour. In the last case we may 

 infer that had he been one of that " Twelfth Night " paity 

 in which the Clown e.xclaims — "1 did impelicos thy 

 gratillity," he would have joined in Sir Andrew Ague- 

 cheek's applause. Herbert Spencer 



NOTES ON THE GEOLOGY OF EAST-CENTRAL 



AFRICA 

 'X' HO UGH many travellers have now penetrated almost 

 -*• every part of Central Africa, and described the main 

 geographical features, yet their accounts have been singu- 

 larly barren in any reliable geological details. The 

 Geographical Society, in its late expedition to the lake 

 region, sought to remedy this want, and 1, as a student of 

 that science, had the honour of being selected as geologist 

 and assistant to Mr. Keith Johnston, the leader of the 

 expedition. 



After the lamentable death of Mr. Johnston, almost at 

 the commencement of our journey, the entire work of the 

 expedition fell into my inexperienced hands, and to per- 

 form that work conscientiously precluded all hope of any- 

 thing but the most superficial geological research. The 

 difficulties in the way were, as in all tropical countries, 

 much increased by the luxuriance of the vegetation, which 

 seldom leaves a rock uncovered and expo.sed to view. 



Notwithstanding these obstacles to geological investiga- 

 tion, however, glimpses of the internal structure of the 

 country traversed were here and there obtained, which I 

 think may fairly be considered as shadowing forth the 

 main general features of the geology of the Great Lake 

 Region. 



Let me briefly point these out in the order of their 

 occurrence along our route to Nyassa and Tanganyika. 

 The comparatively unbroken stretch of low-lying country 

 which so markedly borders the East Coast of Africa is 

 formed of two, if not three, raised beaches, elevated in 

 recent times above the sea. They consist chiefly of 

 brick-red sands and clays overlying coral rock. The 

 former have been derived by denudation from the coast 

 ranges, which, consisting of hornblende rocks and others 

 containing a large amount of iron, easily account for the 

 deep-red colour characterising these deposits. The sands 

 are of value as containing the gum copal, of which our 

 best varnishes are made. As the tree from which this 

 gum has been derived is now almost extinct, it would 

 seem that a considerable lapse of time has occurred since 

 these deposits have been formed ; but geologically they 

 must be recent, as among the many insects that have been 

 found imbedded in the copal none, as far as I am aware, 

 are extinct. The Msandarusi, or gum copal tree, has 

 evidently been restricted to the sea-coast, as neither it 

 nor the gum has ever been found as yet in the interior. 



In passing from these sands and clays we step over an 

 immense gap in the geological record, of which no trace 

 remains, as the rocks we next reach are evidently of car- 

 boniferous age. These occupy a variable strip along the 

 base of the mountains, here and there rising into small 

 hills and ranges. 



They are found stretching from at least Mozambique 

 to the Equator. On the Rovuma coal-beds are found. 

 In the Rufigi valley there are red liver-coloured sand- 

 stones with pebbled beds and with interbedded lavas 

 which in one curiously-shaped mountain near Behobeho 

 produce a remarkable step-like appearance. These beds 

 are horizontal, but beneath them are sandstones tilted by 

 the intrusion of eruptive basalts, producing an unconfor- 

 mability which however is probably only local. Further 

 north on the Unyanyembe road from Bogamoyo, and at 

 the base of the mountain I observed on my return march 

 compact beds of fossiliferous limestones, together with 

 shales, &c. 



At Umba, a place north of Pangani, I also discovered 

 limestone, which I believe is now being burnt by the 

 L'niversities Mission Agents. The young geologist, 

 Thornton, the companion of Baron von der Decken, 

 observed this same formation around Mombas, which he 

 noted as being exactly similar to the coal formation of 

 the Zambesi. As no rocks of a later date have been 

 found along the whole of the east coast from Mozambique 

 to the Equator, we may safely infer that this part of the 

 continent has been above water since Carboniferous 

 times, and this inference is strengthened by natural 

 history evidence. 



We have now reached the base of the mountains, and 

 again we are brought face to face with another great 

 break in the series of events. From the Carboniferous 

 sandstones and limestones we pass abruptly to highly 

 metamorphosed rocks whose exact place in the geological 

 series is as yet extremely problematical. These consist 

 of the schists, gneiss, and hornblende rocks which form 

 the mountain range that flanks the great Central Plateau 

 extending from Abyssinia to the Cape. 



In crossing this range we rose to a height of 7000 

 feet. We found the stri'^e of the rocks to be north and 

 south. They present every intermediate grade of varia- 

 tion from the most coarsely crystalline to those with the 

 bedding still traceable. Indeed it would be somewhat 

 1 difficult to point out any sharply-defined line of demar- 

 ; cation between the granites, which seem to predominate 



