290 



NA TURE 



\Feb. 12, 1874 



time of their metamorphism, and showed that it was probably 

 comparatively small. They were in great measure, if not entirely, 

 metamorphosed before the time of the LoAver Old Red sand- 

 slone. But the process of metamorphism was no doubt a very 

 pvolonged one, and we should therefore be prepared to find 

 pro jfs ot its progress at widely separated periods. It is now 

 Well known that low down in the Old Red sandstone of the 

 Midland Valley of Scotland enormous sheets of felspathic lavas 

 and turis occur, forming such chains of hills as the Saidlaws, 

 Ochils, and Peailan Is. No earlier traces ol volcanic action have 

 yet been met with in Scotland, bui these masses pr..ve that when 

 tiiat action began it was developed upon an enormous scale. 

 The author believed the inference might with much probability 

 be drawn that this vast effusion of volcanic material was a con- 

 sequence, or it mighi even be to some extent an accompaniment, 

 ol tne crumpling and metamorphism ot the older Silurian rocks. 

 He drew attention to ti.e way in which these volcanic rocks bor- 

 dered ihe Silurian areas on both sides of the broad lowland val- 

 ley, and to the numerous remarkable bosses of granite, syenite, 

 and porphyry by which the Silurian tracts were pierced. That 

 many of these bosses were formed by the actual fusion of the 

 stratitied rocks themselves seemed to him highly pro lable. But 

 he held also that some of them marked the lower parts of the 

 actual orifices out of which the vole luic materials of the Old 

 Red sandstone had issued. He alluded especially to the singu- 

 lar rounded or dome-shaped hills ol granite, felstone, and quartz- 

 porphyry by which the Siluiian uplai.ds of the southern counties 

 are dotted, and which, from their general lorm and their relations 

 to the surrounding stratified rocks recall some of the characters 

 of true volcanic "necks." The sheets of lavaand tuff have been 

 preserved in the broad lowland vailcy owing to faulting and sub- 

 sidence, while they he been removed from the surrounding hills 

 by denudatiun, so as to uncover the roots ol the pipes or funnels 

 from which they were emitted. After the enormous masses of 

 volcanic materials erupied during the period of the Lower Old 

 Red sandstone, the underground forces graoually declined in 

 vigour, and as the author had shown, became reduced in Per- 

 mian times to the production of a lew small cones scattered over 

 the midland valley, and down the valley of the Nith. The re- 

 mainder of the paper was devoted to the Tertiary volcanic rocks 

 ol the western Highlands. The author showed that in Skye, 

 Raasay, and Mull, masses of granite and quartz-porphyry were 

 associated with the volcanic rocks in such a way as to suggest a 

 community of origin. Even at a distance from the main mass of 

 the basalt plateaux, graniie occurred which was almost certainly 

 of Tertiary date. The picturesque granite of Arran, for example, 

 which had long been known to be at least post-carboniferous, he 

 now firmly believed to be ol the same age as the terraced hills of 

 Skye and Mull, that is, younger in date than the solt clays on 

 which London is built, and it appeared to be associated with 

 actual coulees which had,in some cases, sutfeied an enormous denu- 

 dation like that of the Scur of Eigg. He had not yet been able to 

 show that the renewed and prodigious outburst of volcanic action in 

 Tertiary times had been associated with the metamorphism ot any 

 wide region, and perhaps no dala are obtainable to throw light 

 upon ttiis question. But the extravasation of granite rocks at 

 several places seemed to indicate that metamorphism had taken 

 place, and at least showed, as Mr. Jukes lung ago pointed out, 

 that molten granite might be associated with true volcanic action, 

 though it did not reach the surlace as granite. — On fossil cones 

 fronrthe Airdrie black-band ironstone, by G. A. Panton. — 

 Notes on the geology ol India, by Andrew Taylor. , 



Manchester 

 Literary and Philosophical Society, Jan. 27. — R. Angus 

 Smith, F.R.S., vice-president, in the chair. — "On a Source 

 of Error in Meicurial Ihermometers,'' by Thomas AL Morgan, 

 Student in the Laboratory ol Owens College. While engaged 

 ill distillation, the thermometer, which was placed in a Wurtz 

 tube so that the column of mercury was entirely surrounded by 

 tlie vapour of the distilling liquid, was found after some days to 

 indicate three degrees too little — a discrepancy caused by volati 

 lisatioa irom the surface ol the column ol mercury and conden- 

 sation on the upper part of the tube. By causing tne mercury 

 to flow to the end of the tube and back, the condensed portion 

 was gaiheied up and the correct temperature indicated. It has 

 since been observed that afer each day of distillation, with 

 liquids boiling between Oo" ui.d 100° C, a quantity of mercury 

 equal to i" or i"'5 volatilises. — "Notes on fossil Lithothamnia 

 so-cailed NuUipora;)," by Arthur Wm. Waters, F.G.S. These 

 attain their greatest development in the Leilhakalk, a miocene 



formation which is principally, in some cases almost entirely, 

 composed of these algae. But they are m no way confined to the 

 Leithakalk, being also very abundant in the eocene, especially 

 the upper division ; the so-called granit-marmor, or Bavarian 

 marble, a nummulitic formation, is very largely composed of this 

 concretionary-looking body. In North Italy it abounds in the 

 eocene fijimations which are so largely developed in the Veronese 

 and Vicentin. In many places the formation is some hundred 

 eet, much more than half composed of the Lithothamnium. It 

 occurs abundantly in Hungary and Switzerland. The so-called 

 pisolithic limestone of Paris is according to Giimbel about eight- 

 tenths stone algoe ; also M. Mario, Astrup ; the plciocene of 

 Castel Arquaio ; and in fact it seems to be found m most ol the 

 teniaries on the Continen' ; it is further found in the chalk at 

 Maestiicht, and in the Jurassic sponge beds at Schwabenbergs. 

 The object of this paper is to draw attention to the great masses 

 ol these bodies and the importance of always noticing their oc- 

 currence in geological formations, smce it should be a very 

 material help m regard to the climate, and the conditions of the 

 coasts and currents, besides being of great stratigraphical 

 assistance ; nor is it of less importance to note carelully the 

 growth of recent ones, for only through a knowledge of the 

 present can we mierpret the past. 

 Paris 

 Academy of Sciences, Jan. 26. — M. Bertrand in the 

 chair. — The following papers were read : — Note on magnet- 

 ism, in answer to M. Gaugain, by M. J. Jamin. — Direct demon- 

 stration of the equation / -^ = obyM. A.Ledieu. Thiswasa 



continuation of the paper read at the last session of the Academy 

 by the same author. — Note on the Rhone irrigation canal, by 

 M. A. Dumont. — Several papers on the action of water on lead, 

 were received. — Organogenesis compared with androgencsis 

 [I'androck), by M. Ad. Chatm. This part of the paper dealt 

 with the Saxijia^cs and Crassiilaciic. — On the lateral solfataras 

 of the Chili volcanoe.'^, and on certain n-w minerals, by M. L. 

 Domeyko. — On the history of the question as to the passage ol 

 birds through the air, by M. A. Penaucl. — On the shocks ot 

 earthquake at Nice, by M. Prost. — Determination of the pluck- 

 erian numbers of envelopes, by M. H. G. Zeuthen. — On the 

 apparent orbit and period' of revolution of the doable star j,' Her- 

 culis, by M. Flammarion. — On the variable state ol voltaic 

 currents, by M. P. Plazern.r. This was an answer to M. 

 Cazin's recent remarks on the subject. — On a new sacchavo- 

 meier and a new method of obtaining an absolutely monochro- 

 matic sodium flame, by M. Laurent. The latter object is 

 attained by interposing a cleavage plate of a crystal of potassic 

 dichromate between the polariser and the flame. This ab- 

 sorbs nearly everything but the yellow fight of the flame. — 

 Researches on the flow of liquids through capillary tubes, by 

 M. A. Guerout. — On a new laboratory balance, by AL Deleuil. 

 — On eihyhc oxalurate and oxamethane cyanurate, by M. E. 

 Gnmaux. — On the grafting of dental follicles and of their con- 

 stituent organs, separately by M. Legrosand Magitot. — Remarks 

 on M. Martin's paper on the comparison of the anterior member 

 of the '■^ Montotrmils" with those of birds and leptiles, by M. 

 E. Alix. — Note on the ammoniacal fermentation of urine, by 

 M. A. Lailler. — On the pretended emission of ozone by plants, 

 by M. J. Bcllucci. The author had made a number ol com- 

 parative experiments on this subject. He found the colouration 

 of the test paper to be due to the combined action ol light and 

 moisture. 



CONTENTS Pagb 



A MiNisTEK FOR Science 277 



Pink AND Webster's "Analytical Chemistkv" 278 



The Races of Mankind 279 



Our Hook shelf 280 



Lbtteks to the Editor : — 



The PhotoRr.iph!c Society.— H. E Pk-itchard, F.C-S. Hon. Sec. iSo 



Animal Locomotion— J. Ward; Dr J. B. Pettigrew, F.R.S. . 280 



Specific Gravity of Sea-w.iter—Ur. W. L. Carpenter, F.R.S. . 282 



The LrNN.eAN Society 262 



PoLARrs.iTioN or Light, IV. By W. Spottiswoode. Treas. R.S. 



(With Dijsr.im) :S2 



A Complete Specimen of A PAi..tDTHEKn;M ((K«/iy^/w//-a//<j«) . 285 



Mars. By Rev. T. W Webb (With lllustratwn) 287 



The Admiralty Charts of the PAapic, Atlantic, and Indian 



Oceans • 2S9 



Mr. Gakrod's New Classification of Birds 290 



Notes 293 



Societies and Academies 294 



