43 2 



NATURE 



[March 4, 1SS0 



it was shewn that for fair comparison the coarser and the finest 

 particles should be separated by sieving and washing, so as to 

 obtain clean grains having on an average a diameter of about 

 1 l Tr th of an'inch. On examining such sand from different 

 deposits and different localities, it is seen that the amount of 

 wearing varies very greatly. Much remains to be learned 

 respecting the detail, but the observations made hitherto show 

 that certain deposits are as if derived almost directly from 

 crystalline rock-, that a very considerable amount of mechanical 

 action is required to round angular grains of quartz T ^;th of 

 an inch in diameter, and that in proceeding from the apparent 

 source in crystalline rocks the amount of wearing increases, 

 until, when the sand has been drifted for ioo or 200 miles, 

 about one-half of the grains are well worn and rounded. The 

 uniformity in character over wide districts is sometimes remark- 

 able and very characteristic. 



Certain special questions connected with the structure of fine- 

 grained deposits were then considered, amongst which may be 

 specially mentioned the lamination of shales. It was shown that 

 after complete subsidence such finegrained muds contain so 

 much included water that if squeezed out by the vertical pressure 

 of superincumbent s rata, the bulk would be reduced to at least 

 Jth, which would necessarily develop a fissile structure in the 

 plane of stratification, analogous to, but much less perfect than, 

 the transverse cleavage of slates due to lateral pressure. 



The nature of the more characteristic materials of fine-grained 

 slates was next considered, and it was shown that they must 

 originally have often differed very greatly from the more modern 

 deposits of granular mud to a great extent derived from the 

 decomposition of granitic rocks, this difference being mainly due 

 to their having been derived to a large extent from the decom- 

 position of the fine-grained basis of certain felsitic ashes. On 

 the contrary, the characteristic features of the green slates of the 

 English Lake District are m inly due to the material having been 

 derived from a mere doleritic type of ash. Oi:e of the most 

 striking facts is the great amount of true pumice, the originally 

 empty cells of which are now filled with calcite or with various 

 green minerals, in the same manner that the cells of faraminifera 

 are often found filled with glauc 



The author then pointed out how some difficulties connected 

 with the mechanical origin of slaty cleavage could be easily 

 removed, and traced the gradual passage from an ordinary strati- 

 fied, non-cleaved slate to one with an imperfect cleavage due to 

 the development of close joints or planes of discontinuity, and 

 finally to a perfect cleavage, when the yielding of the mass to 

 lateral pressure was sufficiently great. 



The next questions w hich claimed attention were connected 

 with the chemical changes that have occurred in the rocks since 

 they were deposited. These have often given rise to a well- 

 marked group of minerals, of several different kinds, but usually 

 of green colour, and their development has played an important 

 part in strata of nearly every age, resulting in the formation not 

 only of the green grains of the green sand, but also in the 

 analogous green constituents of many slate=. 



The author then discu-sed very carefully the gradual develop- 

 ment of mica-schist, tracing it from what might be called its very 

 germs, in grains only -355th of an inch in diameter, formed in 

 situ in some slates, to cases in which the whole of the original 

 constituents of the slate have re-crystallised in situ into mica and 

 quartz. In rocks of this type we can clearly see that the folia- 

 tion is not due to deposition, but to crystallisation, which has 

 .ceo greatly influenced, not only by the previously existing 

 structures due to stratification, but also by those due to cleavage 

 previously developed by lateral pressure. Such fine-grained 

 connecting links between elates and schists differ from true schists 

 jnly in being of finer grain, which is sometimes so fine that with 

 the naked eye it would be almost impossible to di.-tingnish 

 between the.n and slates, though the microscope shows that true 

 dates have been deposited as mud, whilst the tine-grained schists 

 have re-crystallised in situ. 



The author concluded by specially considering what evidence 

 remained in the m 1st typical schi-tose rocks of the former presence 

 of the grains of sand and of the fine granular particles found in 

 slates, and showed that ah hough they could sometimes be de- 

 tected, yet in many cases the whole rock is so completely 

 crystalline, that all evidence had been obliterated. The proof 

 of crystallisation in situ is, however, very complete, so that, 

 though we can see clearly that the original rock must have been 

 greatly changed, we cannot really prove from its structure what 

 the rock originally was — whether it was detrital or a mass of 



small crystals. This re-crystallisation of the material in 



is more especially proved by the structure of those schists which 



possess cleavage foliation. This differs most characteristically 



from stratification foliation, and clearly proves that before 

 crystallisation took place the structure of the rock had 

 altered by lateral pressure. 



It will thus be seen that the main object of the address was to 

 trace the origin of the constituents of modern or more ancient 

 sand and mud from pre-existing crystalline rocks of different 

 types, and to show the correlation of the most modern and the 

 most ancient deposits, and finally to trace the changes that have 

 occurred since deposition, until they reach their extreme in 

 reproduction of crystalline rocks, thus completing the entire 

 cycle of chemical and mechanical changes. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 

 The petitions of Owens College and Yorkshire College rela- 

 tive to the creation of the "Victoria" University, have been 

 printed as a parliamentary paper, with the draft of the proposed 

 charter, the main heads of which we have already given. We 

 believe this draft now only awaits the sanction of Parliament to 

 become law. 



Dr. William Ramsay, of the chemical laboratory of the 

 University of Glasgow, has been appointed to the Chair of 

 Chemistry in University College, Eri-tol, in room of Dr. Letts, 

 who has succeeded Dr. Andrews in Queen's College, Belfast. 



Mr. T. J. Parker, B.Sc. (Lond.), sin of Prof. W. K. 

 Tarker, F.R.S., has been selected for the Professorship of 

 Biology in the University of Otago, New Zealand, and Curator- 

 ship of the Otago Museum. Mr. Parker has for some years 

 been Demon>tralor of Biology in the laboratory of the Royal 

 School of Mines, South Kensington. We understand that three 

 Commissioners were appointed by the University Council to 

 report on the qualifications of candidates. The candidates, we 

 believe, were numerous and highly qualified. 



Prof. Lowig, who occupies the chair of chemi-try at the 

 University of Bie lau, celebrates on April 7 the fiftieth year of 

 bis doctorate. As his laboratory courses have always been 

 largely attended by pharmaceutical chemists, of whom over 

 l,ooo have pursued their studies under his guidance, a movement 

 has been set on foot to endow in he nour of the occasion a 

 pharmaceutical scholarship, to bear the name of the veteran 

 professor. Although the University of Breslau occupies by 

 no means the first rank among German universities, still the 

 salary and fees falling to the share of the occupant of the 

 chair of chemistry, form a sum far in excess of that received by 

 any other professor of chemistry in the empire. Second on the 

 list in this regard is the professorship of chemistry at Wiirzburg, 

 now held by Prof. Wislicenus. In both ca^es the fact is mainly 

 due to the large affluence of medical students who are forced to 

 take courses of chemical lectures. 



The authorities of the Zurich Polytechnic are making prepara- 

 tions t 1 celebrate next August the twenty-fifth anniversary of the 

 foundation of the institution. In view of the widespread influ- 

 ence which the Polytechnic has exerted on the recent develop- 

 ment not only of the canton but of the entire republic the 

 occasion will be one cf no slight inter, 



IwcNcue Freu Prcsse makes the following comparison of 

 schools and school attendance in different European countries : — 

 Germany, with a population of 42,oco,oco, has 60,000 schools 

 and an attendance of 6,000,000 pupils ; Great Britain and Ire- 

 land, with a population of 34,000,000, has 5S,coo schools and 

 3,000,000 pupils ; Austria-Hungary, with a population of 

 37,000,000, has 30,000 schools and 3,000,000 pupils ; France, 

 with a population of 37,000,000, has 71,000 schools and 

 4,700,000 pupils; Spain, with a population of 17,000,000, has 

 20,000 schools and i,6oo,coo pupils ; Italy, with a popula- 

 tion of 2S,ooo,ooo, has 47,000 schools and 1,900,000 pupils ; 

 and Russia, with a population of 74,000,000, has 32,000 schools 

 and 1,100,000 pupils. 



SCIENTIFIC SERIALS 



The yearned of the Royal Microscopical Society, containing its 



transactions and proceedings and a record of current researches 



relating to invertebrata, cryptogamia, and microscopy, Feb- 



