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interest teachers most, that is "teaching and learning processes' and 'teacher pupil relationships'. The third addresses the preoccupations of sociologists, it is the 'processes of social differentiation in primary schools'. Pollard goes on to establish the perspectives of both teachers and pupils in schools, and he documents the things that are most important to them. He employs notions of 'interests at hand, self image and identity' and shows how they operate on a daily classroom basis. He looks in detail at the processes of negotiation and adaptation, which teachers do in the face of the realities of classroom life. And so, demonstrates the ways that identity and personality determine a lot of teachers' style. Pollard also gives priority, to the now well established demand within qualitative sociology, of documenting the role pupils play in constructing the social reality of the classroom. They are taken account of, and viewed as active agents in their schooling situation. The approach brings into sharp focus, the fact that, "The threat to the self image of both parties is inherently high in any classroom situation". Therefore in Pollard's view, 'teachers and children put considerable effort into developing ways of coping with it.' He also emphasises that, when the coping breaks down, considerble stress and anxiety result.

Faced with the question of what matters in survival, we have a choice of seemingly alternative answers. Let us use the term 'person-stage' as in recent articles by David Lewis and Derek Parfit, and let us, like them, call the relation between two person-stages which belong to the same person the 'I-relation'.' Our apparent alternatives are, then, the thesis that the I-relation is what matters (which common sense seems to suggest) and the view that what matters is a psychological relation between person-stages. An important argument for regarding the answers as alternatives is furnished by the case of fission. A person-stage S belongs to a person C. At a later date a person-stage S, belongs to a person C, and a contemporary but non-identical person-stage S2 belongs to C2. Following Lewis, let us call the psychological relation which, arguably, matters in survival (psychological continuity and/or connectedness) the 'R-relation'. Now suppose that S, and S2 are both R-related to S. Are they both I-related to S? It is commonly argued that they cannot be (by Parfit among others, in his i97i article on personal identity).2 Since identity is transitive and symmetrical it is natural to anticipate that the I-relation is transitive and symmetrical. So if S, and S2 are both I-related to S they will have to be I-related to each other. At least one of S, and S2, therefore, is apparently R-related to S without being I-related to S. The moral, allegedly, is that Rand I-relations are not coextensive, and thus cannot both be what matters in survival. Lewis, unlike Parfit, denies that the two answers to the question of what matters are rivals. According to him the I-relation is the same as the R-relation. He claims not only that a person is a maximal Iinterrelated aggregate of person-stages (I shall accept this without discussion, since it seems to be no more than is implicit in the idea of a person-stage), but also that it is a maximal R-interrelated aggregate of person-stages (Lewis, p. 22). He offers an ingenious treatment of the fission case which seeks to make it consistent with his claims. According to Lewis S is a stage of both C, and C2, but C, and C2 are not the same person. So S, and S2 are not I-related, even though they are both I-related to S. Although he believes that the I-relation is symmetrical, by claiming that it is not transitive he tries to undermine the argument summarized in the previous paragraph.3

easily be introduced as a linguistic distinction between two ways of talking about time, although it is arguable that there is a corresponding distinction between two types of temporal facts. The first type of temporal language includes tense proper in the grammatical sense, temporal demonstratives such as 'now' and 'today', and the terms 'past', 'present' and 'future' which at least superficially behave as predicates of events. It is a common opinion that this is not the rag-bag which it might appear to the uninitiated. I shall follow recent practice2 in referring to the whole category as 'tensed language'. One significant feature common to this type of terminology is that any sentence involving an expression of this type has the property that not all tokens of the sentence have the same truth-value. For example a token of the sentence 'it is raining today' uttered on St Swithin's day may have the value true while one uttered on Christmas Day may have the value false. In this respect tensed language is in marked and celebrated contrast to the other type of terminology, to be called here 'untensed'. Untensed language relies on the relational predicates 'earlier than', 'later than' and 'simultaneous with', together with a liberal use of dates. By these means it is possible to produce sentences which are eternal in the sense that every one of their tokens has the same truth-value. If one token of the

Kinetic studies of the early stages of the oxidation of pure iron, initiated at a clean metal surface, have been carried out at a pressure of 76 mm Hg absolute, and isothermally in the range 700–90...

An apparatus which includes essentially a Rotameter for the measurement of small rates of flow of gas is designed to enable instantaneous reaction rates of gas-solid reactions to be obtained continuously.

A volumetric method has been used to study the kinetics of the initial oxidation of oure iron at two pressures of dry oxygen (viz. p O2 = 7·6 and 29 cm mercury) in the range 800–1000° in which the first allotropic transformation point of iron occurs. It was found that the oxidation of both body-centred cubic (b.c.c.) and face-centred cubic (f.c.c.)–iron at p O2 = 7·6 cm and of only b.c.c. at p O2 = 29 cm follows a modified parabolic law; a true parabolic law was found to operate in the oxidation of f.c.c.–iron only at p O2 = 29 cm. An anomaly, which is obtained in the Arrhenius plot at the allotropic change point of iron (∼911°), is attributed to the effect of phase-boundary reactions on the oxidation kinetics. It would appear from the concept of vacancy distribution in iron, that for a modified parabolic law, it is the metal/oxide interfacial reaction in f.c.c.–iron and the oxide/oxygeninterfacial reaction in b.c.c.–iron that governs the phase-boundary controlled reaction rate.

The Paper refers briefly the London County Council's scheme for development of the South Bank area, and describes the main features of the Shell Centre which is divided into an upstream and a downstream section. A feature of the former is a tower block 351 ft high. An account is given of the ground conditions over the site and of considerations concerning the effects of extraordinary high tides. Retaining walls of prestressed concrete were designed to act as simple cantilevers. Prestressing of the walls is described. The basement of the upstream section was constructed over the tunnels of the Bakerloo Railway and its floor level was only about 7 ft above the crown of one tunnel. Special measura and precautions were taken to avoid damage to the tunnels. Calculations were made of the probable heave of the tunnels during basement excavation and careful observations carried out of the actual heave. The distortions of the tunnels were measured. The buildings are extensive, with wide differences in the foundation loading under various sections. Differential settlements had to be considered carefully and measures taken to minimize their effects. The tower block and certain other parts of the upstream section were founded upon cylinders which were generally formed by machine auger. Water was excluded from the basements by the retaining walls which formed a cut-off in the London clay. Reliance was placed upon the watertightness of the concrete in the retaining walls. These were divided into short lengths, with water bars in the joints. The upstream and the downstream sections are connected by a subway under the brick arch of the Waterloo-charing Cross railway viaduct. The construction of this subway immediately adjacetnot shallow viaduct foundations carrying heavy locomotives called for special measures. Cooling water for the air conditioning system of the building is drawn from the River Thames through a tunnel in the London clay. This was driven by hand without a shield. Compressed air was applied to the section of tunnel under the river. The framework of the tower block is steel. Up to second floor level this takes the form of welded rigid frames. Above second floor level lateral strength is provided by moment connexions with high-strength bolts, in combination with bracings incorporated in fixed wall positions. Measures taken by the contractor to achieve a high speed of construction are described briefly.

So far very little attention has been given to thin oxide films on cobalt1. This report deals with the structural features observed by transmission electron microscopy of chemically stripped films (from hundreds to a few thousands A thick) formed on cobalt. The material used was spectrographically pure polycrystalline cobalt supplied by Johnson Matthey and Co., Ltd, in the form of rolled strips (0.05 cm thick). X-ray diffraction of the metal as received revealed the structure as hexagonal close packed (h.c.p.). Studies of the oxidation2 as well as the dilatometric curve of the metal indicated a change in the crystal structure about 386° C, which is presumably due to the allotropic transformation of cobalt from h.c.p. to face-centred cubic (f.c.c.) form.

We demonstrate a novel dual-beam particle trap relying on waveguide loss instead of beam divergence. The implementation of this trap on an optofluidic chip opens numerous possibilities for on-chip particle control and manipulation.

We review recent development of liquid-core ARROW waveguides for combining planar integrated optics and microfluidics on a chip. Optical design, microfabrication, and optical characterization are presented, including demonstration of single molecule fluorescence sensitivity.

An integrated filter utilizing liftoff-based selective patterning is designed, fabricated, and demonstrated. The waveguide acts as a notch filter in the collection path of an optofluidic device and exhibits ??~1.4nm and ~22dB rejection over 18mm.