July 7, 1910] 



NATURE 



the State Experimental Farm at Ottawa, the University 

 of Toronto, the Ontario College of Agriculture at Guelph, 

 Cornell University, Wisconsin University, and Harvard 

 University. In each case the members of the deputation 

 made it their principal object to acquaint themselves with 

 the agricultural activities of the institution visited, and 

 their work was greatly facilitated by the cordial assistance 

 of the Government and other authorities both in Canada 

 and in the United States. It is hoped to publish a report 

 during the course of the ensuing autumn containing the 

 substance of the information gained and emphasising 

 certain conclusions. 



The igio report of the council of the City and Guilds 

 of London Institute to the members of the institute is 

 now available. As usual, full particulars are provided of 

 the work done during the previous year at the Central 

 Technical College, the Finsbury Technical College, the 

 other schools and colleges in connection with the institute, 

 and the department of technology. In the section of the 

 report dealing with the department of technology, it is 

 pointed out that the preliminary education of candidates 

 who enter technical classes is evidently very often the 

 reverse of satisfactory. It was noted in the last report 

 that the institute, in conjunction with the Board of Educa- 

 tion, was taking active steps to encourage the attendance 

 of young persons engaged in different trades at evening 

 continuation classes, with the view of their acquiring a 

 competent knowledge of English, arithmetic, drawing, and 

 elementary science before entering upon their first year's 

 course of training in technology. The committee regrets, 

 however, to state that it has been found very difficult to 

 enforce the regulations introduced in 1908, by which, in 

 certain textile subjects, students of registered classes In 

 technology were only to be admitted to the first year's 

 examination on satisfying the institute that they possessed 

 t!ie necessary preliminary knowledge. Notwithstanding the 

 growth of group courses and the increased facilities for the 

 altendance of students at evening continuation classes, it 

 has not been found possible to insist on evidence of attend- 

 ance at continuation classes prior to the admission of 

 students to a technical school. It has proved necessary 

 to decide that the full enforcement of the regulations in 

 question should be postponed until igi2. Commenting on 

 the results of the examinations conducted throughout the 

 country by the institute, the report says the Independent 

 criticisms from examiners in wholly distinct subjects show 

 that many teachers, while undoubtedly using their best 

 efforts to acquaint the students with the technical details 

 of their trade, fail to obtain good results owing to their 

 giving instruction on wrong lines, paying too much atten- 

 tion to description and too little to the theory of the sub- 

 ject and to the principles underlying the work in which 

 they are engaged. This may be partially due to lack of 

 experience in teaching and failure to realise the difficulties 

 of their students. The institute concurs in a suggestion 

 made by its inspectors that if the education authority 

 could send a comparatively inexperienced teacher to visit 

 some of the schools at which successful classes are con- 

 ducted and see their methods of work, such a visit would 

 amply repay its cost. 



SOCIETIES AND ACADEMIES. 

 London. 

 Geological Society, lime 15. — Pr^r. W. W. Waits, 

 F.R.S., president, in the" chair. — Dr. W. Cross: The 

 natural classification of igneous rocks. The author re- 

 viewed the various systems of classification which have 

 been proposed. He discussed the origin of the difference 

 of composition of igneous rocks due to : — (i) primaeval 

 difference, (2) magmatic differentiation, {3) assimilation, 

 and pointed out that differentiation and assimilation are 

 in a measure antithetical processes. The following general 

 conclusions were formulated : — The scientific logical classi- 

 fication of igneous rocks must apparently be based on the 

 quantitative developnient of fundamental characters, and 

 the divisions of the scheme must have sharp artificial 

 boundaries, since none exist in nature. Chemical composi- 

 tion is the fundamental character of igneous rocks, but it 

 may be advantageously expressed for classificatory pur- 



NO. 2123, VOL. 84] 



poses in terms of simple compounds, which represent either 

 rock-making minerals or molecules entering into iso- 

 morphous mixtures in known minerals. It is probable 

 that the magmatic solution consists of such molecules, 

 and that the norm of the " quantitative system " is a 

 fairly representative set of these compounds. The actual 

 mineral and textural characters of igneous rocks are 

 variable qualifiers of each chemical unit, and should be 

 applied as such to terms indicating magmatic character. 

 — H. Bury : The denudation of the western end of the 

 Weald. There are two main theories of Wealden denuda- 

 tion : — (i) attributing the removal of most of the Chalk 

 to marine planation ; and (2) denying planation, and rely- 

 ing solely on subaerial denudation. Prof. W. M. Davis's 

 suggestion of a subaeria! peneplain forms a sort of con- 

 necting link between the two. The evidence in favour of 

 planation whiclj Ramsay and Topley brought forward is 

 inconclusive, and might plausibly, if it stood alone, be 

 attributed to pre-Eocene causes. On the other hand, 

 I'restwich's arguments against planation are equally weak, 

 while the Chalk plateau to which he directs attention 

 strongly supports Ramsay's views. The distribution of 

 chert is fatal to Prof. Davis's hypothesis, and very 

 difficult to account for, except on the marine theory. In 

 the case of the river Blackwater it can be proved that, 

 long after the Hythe beds of Hindhead were uncovered, 

 the river-system remained extremely immature, and this 

 affords very strong grounds for the acceptance of the 

 marine hypothesis. The evidence of the other western 

 rivers is less conclusive, though the Wey and the Mo'e 

 both provide minor arguments pointing in the same direc- 

 tion. The anomalous position of the Arun, at the foot of 

 the northern escarpment of the Lower Greensand on 

 either side of the Wey, is almost certainly due to com- 

 paratively recent captures from the latter river, and affords 

 no ground for assuming a river-system of great age 

 matured on a Miocene peninsula. There is no proof that 

 anv of the existing connections between rivers and longi- 

 tudinal folds are of a primitive character, and, on the 

 other hand, there are many alleged examples of transverse 

 disturbances having served as guides to consequent rivers. 

 This again, on the whole, supports the marine hypothesis, 

 especially if, as there are reasons for believing, the longi- 

 tudinal folds are older than the transverse. — Dr. J. W. 

 Evans ; .^n earthquake model. This model is designed to 

 show the successive conditions that result in an earth- 

 quake shock : — (i) slow relative movement between two 

 extensive portions of the earth's crust lasting over a long 

 period, and causing (2) a state of strain in the intervening 

 tract, leading to (3) fracture which relieves the strain and 

 allows (4) the adjoining portions of the rock on either 

 side to fly back by virtue of their elasticity,^ so as to 

 resume, so far as possible, their original relation to the 

 rock-masses with which they are still connected. This 

 movement of release may give rise to two kinds of periodic 

 disturbance : (5) short-period vibrations, due to a sudden 

 arrest by an obstacle and constituting the earthquake 

 properly so called, and (6) a slower backward and forward 

 swing of the rock about the position of equilibrium. 



Royal Microscopical Society, June 75.— Prof. J. Ar'hui 

 Thomson, president, in the chair.— Prof. J. -'\rthur 

 Thomson: Some alcyonarians collected by Mr. J. Murray, 

 of Sir E. Shackleton's Antarctic Expedition. The species, 

 of which there were four, were Clavularia rosea, Studer, 

 C. chiini, Kiikenthal, Alcyonium paessleri, May, and 

 Ceratoises delicatula, Hickson.— E. M. Nelson : Apparatus 

 for increasing the power of an achromatic condenser.— 

 E. B. Stringer : The use of the mercury vapour lamp m 

 observing the rings and brushes in crystals. 



Linnean Society. Tune i6.-Dr. D. H. Scott. F.R S., 

 president, in the chair.— Dr. R. N. Salaman : Male 

 sterility in potatoes, a dominant Mendehan character, with 

 remarks on the shape of the pollen in wild and domestic 

 varieties. The paper was based upon experiments made by 

 the author in his own garden at Barley, near Royston, 

 Herts, during the past four years ; but on this occasion 

 the author confined his remarks to the pollen, leaving other 

 points for some future occasion. He pointed out that 

 "dead" pollen-grains, or none, were usually associated 

 with flowers of heliotrope colour. 



