336 



NATURE 



[Peh. 2 1, 1^78 



Although no traces of the upper oolite or the neocomian forma- 

 tions have as yet been detected in the Western Highlands, yet it 

 is argued that when we consider how enormous has been the 

 amount of denudation, and how singular the accidents to which 

 all the existing relics of the secondary period have owed their 

 escape from total destruction, we cannot but regard it as a most 

 rash and unwarrantable inference to conclude that no deposits 

 belonging to those periods were ever accumulated within the 

 district under consideration. The carboniferous strata of the 

 Western Highlands have been detected at but a single locality ; 

 and even there, being exposed in a series of shore reefs that are 

 only occasionally well displayed, can only be studied under 

 favourable conditions of tide and wind. They consist of sand- 

 stones and shales with thin coaly seams, and their age is placed 

 beyond question by the discovery in them of many well-known 

 plants of the coal-measures, including species of Lepidodendron, 

 Calamiies, Sigillaria, and Stigmaria. The poikilitic strata con- 

 sist of conglomerates and breccias at the base, graduating upwards 

 into red marls and variegated sandstone, which contain concre- 

 tionary limestones and occasional bands of gypsum. These strata 

 have not as yet, like their equivalents in the Eastern Highlands 

 (the reptiliferous sandstone of Elgin and the Stotfield rock) 

 yielded any vertebrate remains. They were evidently deposited 

 under similar conditions with the beds of the same age in 

 England, and are not improbably of lacustrine origin. The 

 Jurassic series presents many features of very great interest. The 

 infralias is better developed than is perhaps the case in any part 

 of the British Islands ; and in the district of Applecross a series 

 of estuarine beds, containing thin coal-seams, is found to be in- 

 tercalated with the marme strata. The lower lias, in its southern 

 exposures, presents the most striking agreement with the equiva- 

 lent strata in England, but when traced northwards exhibits 

 evidence of having been deposited under more littoral conditions ; 

 the lower division (lias a, Quenstedt) is represented by a great 

 thickness of strata ; while the upper (lias /3) is absent or rudi- 

 mentary. The middle lias is grandly developed, and consists of 

 a lower argillaceous member and an upper arenaceous one, the 

 united thickness of which is not less than 500 feet. The upper 

 lias singularly resembles in the succession of its beds, and its 

 palceontological characters, the same formation in England. The 

 inferior oolite is formed by series of strata varying greatly in 

 character within short distances, and betraying sufficient signs of 

 having been accumulated under shallow- water conditions. Above 

 the inferior oolite we find a grand series of estuarine strata, partly 

 arenaceous and partly calcareo-argillaceous ; and this is in turn 

 covered conformably by an unknown thickness of blue clays with 

 marine fossils of middle Oxfordian age. At the very lowest 

 estimate, the Jurassic series of the Western Highlands could not 

 have had a thickness of less than 3,000 feet ! The cretaceous 

 strata, of the Western Highlands, though of no great thickness, 

 are of surpassing interest. They consist of two marine series 

 alternating with two others of estuarine origin. At the base 

 we find marine deposits of upper greensand age, strikingly 

 similar to those of Antrim, but in places passing into conglome- 

 rates along old shore lines. Above the upper greensand beds 

 occur unfossiliferous sandstones, in which thin coal-seams have 

 been detected, and these are in turn covered by strata of chalk, 

 converted into a siliceous rock, but still retaining in its casts of 

 fossils {Beletmdtella, Inoceramus, Spondylus, &c.), and in its 

 beautifully preserved microscopic organisms {Foraminifera, Xan- 

 thidia, &c.) unmistakable proofs of its age and the conditions of 

 its deposition. Above this representative of the highest member 

 of the English chalk there occur argillaceous strata with coal- 

 seams and plant-remains which are perhaps the equivalent of 

 younger members of the cretaceous series, not elsewhere found 

 in our islands, or, it may be, they must be regarded as belonging 

 to periods intermediate between the cretaceous and tertiary 

 epochs. It is greatly to be regretted that these cretaceous 

 deposits of the Western Highlands are so unfavourably displayed 

 for our study as to present scarcely any facilities far the collection 

 of their fossils ; for these, if found, might be expected to throw 

 a flood of light on some of the most obscure palseontological 

 problems of the present day. Although the comparison and 

 correlation of the secondary strata of the Highlands with those 

 of other areas, and the discussion of the questions of ancient 

 physical geography thereby suggested, are reserved for the fourth 

 and concluding part of his memoir, the author takes the oppor- 

 tunity of making reference, in bringing the present section of his 

 work to a close, to several problems on which the phenomera 

 now described appear to throw important light. In opposition 

 to a recent speculation which would bring into actual continuity 



the present bed of the Atlantic and the old chalk strata of our 

 island, he points to the estuarine strata of the Hebrides as 

 demonstrating the presence of land in that area during the cre- 

 taceous epoch. He also remarks on the singular agreement of 

 the conditions of deposition of both the silurian and cretaceous 

 strata of the Scottish Highlands and those of the North 

 American continent. But he more especially Insists on the 

 proofs, which we now have, that the H ghlands of Scotland, as 

 well as the greater part of the remainder of the British Islands, 

 were once covered by great deposits of secondary strata, and 

 that the area has been subjected to enormous and oft-repeated 

 denudation. He dwells on the evidence of the vast quantities 

 of material which have been removed subsequently to the 

 mesozolc and even to the mlocene period, and he maintains the 

 conclusion that many. If not all, of the great surface-features of 

 the highlands must have been produced daring the very latest 

 division of the tertiary epoch, namely the pliocene. 



Mathematical Society, February 14.— Eord Rayleigh, 

 F.R.S., president, and subsequently Mr. C. W. Merrifield, F.R.S. 

 vice-president, in the chair. — The following conmunicatlon; 

 were made : — ^On a general method of solving partial differential 

 equations, Prof. Lloyd Tanner. — On the conditions for steady 

 motion of a fluid, Prof. Lamb (Adelaide), (particular cases of 

 the conditions were given by Stokes in the Cambridge Phil. 

 Trans, for 1842). — On a property of a four-piece linkage and 

 on a curious locus in linkages, Mr. A. B. Kempe. — On Robert 

 Flower's new mode of computing logarithms (1771), Mr. S. M. 

 Drach. — On the Pluckerlan characteristics of the modular 

 equations. Prof. H. J. S. Smith, vice-president, F.R.S. — Mr. 

 Drach also exhibited drawings of trlcirclolds male some thirty 

 years since for Mr. Perlgal. 



Royal Microscopical Society, February 6. — Anniversary. — 

 H. C. Sorby, president, in the chair. — The report of the Treasurer 

 was submitted to the meeting. — The report of the Council stated 

 that the library and Instruments of the Society were in a satisfactory 

 condition, and obituary notices of deceased Fellows, Dr. Bowerbank 

 and Dr. Henry Lawson, were read by the Secretary. Messrs. 

 Glalsher and Curtles having been appointed scrutineers, a ballot 

 for ofhcers and council for the ensuing year took place with the 

 following result : — President, H. J. Slack ; Vice-presidents, Dr. 

 L. S. Beale, Dr. C. T. Hudson, Sir John Lubbock, Bart., and 

 Mr. H. C. Sorby ; Treasurer, Mr. J. W. Stephenson ; Secre- 

 taries, Mr, Chas. Stewart and Mr. Frank Crisp ; Council, Mr. 

 John Badcock, Mr. W. A. Bevlngton, Dr. R. Bralthwalte, Mr. 

 Chas. Brooke, Mr. C, J. Fox, Dr. W. J. Gray, Mr. E. W. 

 Jones, Dr. Matthews, Mr. S. J. Mclntire, Dr. John Millar, Mr. 

 Thos. Palmer, and Mr. F. H. Ward ; Assls'.ant-secretary, Mr. 

 Walter W. Reeves. The retiring president then delivered his 

 annual address, which chiefly treated of the results of his investi- 

 gations into a method of obtaining the refractive indices of 

 minerals. 



CONTENTS pagk 



The Head Masters ON Science Teaching. By W. Tuckwell . 317 

 Frankland's Researches in Chemistry. By Prof. J. Emerson 



Reynolds, F.R'S 318 



Flora of Tropical Africa. By Prof. W. R. McNab 319 



Letters to the Editor : — 



Marine Fossils in the Gannister Beds of Northumberland. — Pro'. 



G. A. Lebour 320 



Liquids having a Specific Heat higher than Water. — F. J. M. 



Page 320 



Age of the Sun in Relation to Evolution. — Dr. James Croll . . 321 



The "Phantom" Force. — Prof. A. S. Herschel 32( 



Cumulative Temperatures — Conrad W. Cooke ...... 323 



Bacteria IN Water. By G. F. Dowdeswell 3^3 



Our Astronomical Column : — 



The Uranian Satellites, Ariel and Umbriel 323 



Pigott's Observations of Variab'e Stars 323 



The Temple Observatory, Rugby 324 



Geographical Notes : — 



African Exploration ,. 324 



Arctic Exploration 324 



The Pamir 321 



Educational Travel 324 



Prshevalsky and Maclay 374 



Sea Trade with Siberia 324 



Geographical Bijbliography 324 



Russian Geographical Society 324 



A New Underground Monster 325 



Sun-spots and Declination Ranges. By Prof. Balfour Stewart 326 

 The Islands of St. Paul and Amsterdam. By Prof. E Perceval 



Wright {}Vith Illustrations) 326 



Notes 329 



On Compass Adjustment in Iron Ships. By Sir Wm. Thomson, 



lX..\y.,Y.V..^ (With Illustrations) 331 



University and Educational I NTKLLiGENCB 1 334 



SociBTiBS AND Academies 335 



