2l8 



NATURE 



IJuly 3, 1879 



they are of much newer, and most probably upper green- 

 sand age : to tabulate their fauna with that of the 

 gault, lessens the working value of the tables materially. 

 The upper gault only is thought to be present in the Isle 

 of Wight, where it is 100 feet thick. The little that is 

 known of the gault in the Midland Counties is collected 

 together, and that of Cambridgeshire and the red chalk 

 at Hunstanton is briefly described. A few pages are 

 devoted to the gault in France, a few lines to that of 

 Switzerland, but no mention is made of any equivalents 

 in Germany or in Belgium. The pamphlet contains in a 

 compact form a deal of information upon the gault, which 

 would have to be sought elsewhere in many publications, 

 and it may prove of value to students at home and abroad. 

 The author believes that the bands which are character- 

 ised by fossils peculiar to them at Folkestone, can be 

 traced elsewhere in England and in France. The range 

 through the gault of most fossils is probably less restricted 

 than is imagined, but some species are apparently strictly 

 confined to narrow zones at Folkestone, although closely 

 allied species abound in cretaceous rocks in England, 

 and even America. It is likely that zones of fossils were 

 due to the gradual alteration of depth which enabled 

 certain gregarious forms to e.\ist on the spot for a very 

 short time only after their first migration to it. Their 

 presence elsewhere would not prove that the zone was a 

 continuous one ; it would only indicate that at some 

 period, not necessarily a synchronous one, the sea at that 

 other spot had fulfilled the conditions of depth, &c., under 

 which alone the particular species could exist. The same 

 view applies to the idea that upper gault only was de- 

 posited in the Isle of Wight. There is no reason to 

 suppose that deposition did not proceed there in the lower 

 gault age, and it is more probable that the sea was, 

 during the whole gault period, only fitted to receive that 

 form of silt, and those fossils which are known at Folke- 

 stone as upper gault. The lower gault is spoken of by 

 the author as a shallow sea deposit gradually deepening 

 toj the chalk, but the President of the Geological Society 

 has stated his opinion that the gault is an extremely deep 

 sea deposit, while Mr. Gwyn Jeffreys has collected much 

 evidence to prove that the chalk was formed in shallow 

 water. Whether we accept them or not, the views of 

 such distinguished men should find a place in a work 

 intended to be exhaustive. 



Travels and Researches among the Lakes and Mounlaitts 

 of Eastern and Central Africa. From the fournals of 

 the Late f. Frederic Elton, H.B.M. Consul at Mozam- 

 bique. Edited and Completed by H. B. CotterlU. 

 Maps and Illustrations. (London: Murray, 1879.) 



One cannot read Consul Elton's Journals without feeling 

 how great a loss his death has been not only to the cause 

 of the natire African, but to African exploration. Elton was 

 only thirty-seven years of age when he succumbed to the 

 hardships of African exploration, but he had already done 

 more than his share of hard and useful work. The hand- 

 some and beautifully illustrated volume before us deals 

 with his observations and adventures in Africa from 1873, 

 when he went to Zanzibar as Vice- Consul to his death in 

 December, 1877, when trying to push from the north end 

 of Lake Nyassa to the coast at Dar-es-Salaam. Much of 

 the earlier part of the volume tells of the work Elton did 

 in putting down the slave-trade in the dominions of the 

 Sultan of Zanzibar. In carrying out this work he had to 

 visit most of the coast from Zanzibar to beyond Mozam- 

 bique, as well as Madagascar, and with the details of his 

 more immediate mission, is mixed up a good deal of 

 geographical information. He carried on his works of 

 benevolence and exploration on his appointment as Consul 

 of Mozambique. The chief novelty of the volume, how- 

 ever, is in the second part, in which the story of the 

 journey from the north end of Lake Nyassa north-east to 

 the coast is told. Here Elton, Cotterill, and their com- 



panions broke on fresh ground, and made substantial 

 additions to our knowledge of African geography and 

 African people. With the main results of this journey 

 we are already familiar, through the description of Mr. 

 Cotterill at the Geographical Society and elsewhere. 

 Elton left Mozambique in July, 1877, Livingstonia at the 

 south end of Nyassa in September, and the north end on 

 October 15. The country traversed was mainly hilly, 

 rising in the Konde Mountains, north-west of Nyassa, to 

 12,000 feet. Elton speaks of the country as the " Garden 

 of Africa." The party were delayed for a time in Merere's 

 Country in the Konde Mountains, by one of those little 

 wars, which so often embarrass African explorers, and 

 during the delay some hardships had to be endured, 

 which no doubt told on Elton's health. On December 19 

 he succumbed to what seemed sun-stroke, and was buried 

 under the shade of a baobab in South Ushekke. Cotterill 

 conducted the expedition to Bagamoyo, over what is com- 

 paratively well-known ground. In completing the narra- 

 tive of the expedition and editing his late fellow-traveller's 

 journals, in preference to publishing a narrative of his 

 own, he has acted with an unselfishness which de- 

 serves to be acknowledged. The book is altogether one of 

 much interest. The Rev. A. E. Eaton contributes a short 

 Appendix on the Natural History of the Kungu Fly, out 

 of which the natives to the north of Nyassa make cakes. 



Conic Sections — The Method of Projections. By Rev. S. 



Bolton Kincaid, M.A. (London : Stanford, 1877.) 

 This book has only recently met our notice ; it consists 

 of a series of twenty-nine propositions deriving proofs of 

 many of the chief properties of the ellipse by the method 

 of circular projection. We have not come across any 

 special novelty in the little book, nor have we detected 

 many mistakes, though the lettering, from the use of like 

 letters, we have found in many cases confusing. The 

 figures face the text, and the circle figure is over the 

 elUptical one ; they are in many cases very roughly turned 

 out by the engraver. 



LETTERS TO THE EDITOR 



\The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, or 

 to correspond with the writers of, rejected manuscripts. No 

 notice is taken ff antnymous communications. 



\The Editor urgently requests correspondents to keep their letters as 

 short as possible. 7 he pressure on his space is so great that it 

 is impossible othenvise to ensure the appearance even of com- 

 munications containing interesting arid novel facts ^ 



Comet 1879 c (Swift) 



The follow ing observations may be useful to some of your 

 readers : — On June 25 the comet was compared five times with 

 the star O.A. 3268, with a ring micrometer (power 35) ; on 

 June 28 it was compared eight times with the star Dm + 71°, 184 

 by means of a bar reticule with power 70. The comet has a 

 bright spot near the centre which, on June 25, seemed to me to 

 be nearly equal to a ninth magnitude star ; but on June 28 it 

 was much fainter, although easy to observe with precision after 

 I ih. 30m. The diameter appears to be 2' or 3' in my telescope 

 (of 4J inches aperture) but I cannot see any trace of the tail 

 mentioned by Mr. Swift. The comet is, however, immersed in 

 the twilight now existing at midnight. 



1879. G.M.T. Appt. R.A. Appt Dec. 



Appt. R.A. 

 h. m. s. 



G.M.T. 

 h. m, s. 



June 25 ... II S7 49 - 2 49 37T 

 June 28 ... II 30 20 ... 2 51 I3'3 

 I, Vanbrugh Park, Blackheath 



... +68 41 37 

 ... +71 52 18 



G. L. Tupman 



The Mechanical Theory of Earth-Heat 



In reference to Mr. J. P. Lesley's inquiry as to whether 

 plicated coal-beds are generally converted into anthracite, it has 

 occurred to me that during a residence upon the Somersetshire 

 coal district, thirty years ago, I recollect visiting the Vobster 

 coal-pits, on the northern edge of the Mendip hills. The coal- 

 seams are there exceedingly disturbed. One seam of coal was 



