January 24, 19 18] 



NATURE 



419 



The eighteenth annual general meeting of the Asso- 

 ciation of Public School Science Masters, held on 

 January 8 and 9 at the City of London School, was 

 remarkable for the unanimity shown by members on 

 certain important points. The main aim of the asso- 

 ciation at the present moment is to make it certain 

 that every boy in the public schools should receive 

 training in natural science. This training should be 

 part of the general education of the boys, and should 

 therefore be on lines suitable for those who will not 

 afterwards make science their special study. Such 

 lines were laid down by the association twelve months 

 ago in a pamphlet known as " Science for All," in 

 which prominence was given to the human and bio- 

 logical aspects of the subject. Since this is non-special- 

 ist training, it must be taken in the schools before the 

 average boy reaches the age of sixteen and a half, 

 when a certain degree of specialisation usually begins. 

 These points were referred to by Mr. O. H. Latter, 

 who explained to the members the far-reaching effects 

 of university entrance examinations on curricula. The 

 committee, he said, had been met very sympathetically 

 by Oxford LIniversity in this matter, and negotiations 

 were still going on with Cambridge. During the dis- 

 cussion which followed, the Board of Education policy 

 of grouping science with mathematics in these exam- 

 inations was severely criticised. No enthusiasm was 

 shown for the introduction of "compulsory science" in 

 such examinations, if the main aim can be attained 

 in any other way ; on the other hand, the general feel- 

 ing of the meeting was in favour of removing compul- 

 sion (so far as this means that failure to pass in one 

 subject alone necessarily prevents a boy from passing 

 to the university) from all subjects, with the sole ex- 

 ception- of English. The moderateness of the associa- 

 tion was shown agnin later, when the following reso- 

 lution was passed unanimously : — "That it is desirable 

 that opportunities be given to candidates for science 

 scholarships to offer a historical or other literary sub- 

 ject as subsidiary to their main one." Extracts from 

 .Sir H. H. Johnston's presidential address are given 

 elsewhere in the oresent issue. 



SOCIETIES AND ACADEMIES. 

 London. 

 Geological Society, January 9.— Dr. Alfred Marker, 

 president, in the chair. — L. D. Stamp : The highest 

 Silurian rocks of the Clun Forest District (Shrop- 

 shire). Clun Forest is a district in which Upper Silu- 

 rian rocks crop out over a wide area, interrupted by 

 outliers of Old Red Sandstone. The district is separ- 

 ated from the typical Silurian area of Ludlow by 

 the great line of disturbance that passes through 

 Church Stretton and Old Radnor. The succession of 

 beds compares closely with that in the Ludlow district. 

 The main differences are : — (i) That the Aymestry 

 Limestone is represented by mudstones west of the 

 great fault-line, and (2) that all other divisions show 

 increased thicknesses. There is no evidence of any strati- 

 graphical break. The sequence is complete from the 

 Lower Ludlow rocks up into the Old Red Sandstone, 

 and the changes in lithology are gradual. The extent 

 of Old Red Sandstone, as indicated on present maps, 

 must be restricted, since most of the supposed Old 

 Red Sandstone has been found to belong to the Teme- 

 side group, which here attains a great development. 

 The Silurian age of the beds is shown by the occur- 

 rence of Lingula minima and of characteristic larrjelli- 

 branchs. A comparison with other districts in which 

 Upper Silurian rocks are developed shows that deposi- 

 tion attained its maximum along the Welsh Border, 

 the thickness of the formations decreasing rapidly 



NO. 2517, VOL. 100] 



southwards and eastwards. On the east of the dis- 

 trict — in the neighbourhood of the fault-line — the 

 strata are folded along axes ranging north-north-east- 

 wards parallel to the main fault. Away from the 

 major faults the folding is gentler, and folds ranging 

 nearly due east and west make their appearance. 

 Farther west the north-north-eastward folding and 

 fracturing reappear. 



Mineralogical Society, January 15. — Mr. W. Barlow, 

 president, in the chair.— Dr. j". W. Evang : Diagrams 

 expressing the composition of a rock. These diagrams 

 are intended, like those of Michel L^vy and Miigge, to 

 indicate at a glance the significance of the analysis of 

 a rock or complex mineral silicate. The molecular 

 proportions of the constituents are determined in the 

 usual manner, those of the ferrous and magnesium 

 oxides, however, being doubled. The silica is repre- 

 sented by two rectangles placed side by side, the length 

 of each 'being half the molecular proportion of silica. 

 In one of these rectangles lengths equal to the mole- 

 cular proportions of potash, soda, and lime are 

 measured off in succession, and in the other those of 

 alumina, iron oxide, and magnesia. Thus the 

 same space represents both metallic oxide and silica, 

 and so far as felspars, felspathoids, or aegirine are 

 actually or potentially present, the monoxide and ses- 

 quioxide they contain are, with two molecules of silica, 

 represented by contiguous portions of the two rect- 

 angles. The excess, if any, of lime over available 

 alumina has the silica necessary to form woUastonite, 

 and the excess, if any, of iron oxide over available soda 

 and the magnesia "have the silica required to form 

 orthosilicates. The remaining silica space is then 

 divided up to show the additional silica required or 

 available for the felspars, felspathoids, and aegirine, 

 and that available to convert the orthosilicates of iron 

 and magnesium into metasilicates. The remainder 

 represents free silica or quartz. — Dr. G. F. H. Smith : 

 The use of the gnomonic projection in the calculation 

 of crvstals. If projected on to a plane at right angles 

 to the edge of the zone containing the poles from which 

 bi-angular measurements were made, the diagram 

 takes the form of a net, the nodes of which represent 

 the principal poles. The unit lengths of the net are 

 easily calculated from the data, and once the rect- 

 angular co-ordinates of any node with respect to axes 

 on the diagram have been determined those of the 

 remainder follow by simple addition or subtraction ; 

 the corresponding spherical angles are deduced by a 

 simple calculation. The accuracy of the calculations 

 may be checked from the diagram at every step. To 

 keep the projection corresponding with any crystal 

 within reasonable dimensions it is sometimes convenient 

 to project on to the faces of a cube. The direction of a 

 zone when crossing from one face to another is very 

 simply found from the diagram. 



Mathematical Society, January 17. — Major P. A. 

 MacMahon : A method for studying any convergent 

 j^eries.— G. H. Hardy : Additional note on Dirichlet's 

 divisor problem.— J. H. Grace-. Note on a Diophantine 

 approximation. — K. Amanda Rau :A note on a theorem 

 of Mr. Hardy's.— C. H. Forsyth : Super-normal curves. 

 —Prof. H. Hilton and Miss D. S. Tuck : Plane quartic 

 curves with a tac-node. 



Paris. 

 Academy of Sciences,. December 31, 19 17. — M. Ed. 



Perrier in the chair.— A. Lacroix : The eruption of the 

 Quetzaltepec volcano and the earthquake that destroyed 

 San Salvador (June-July, 19 17). A detailed account 

 of the eruption, gathered from the statements of eye- 

 witnesses and frjm photographs, is given. The great 

 loss of life and damage were mainly due to the earth- 



