The decomposition of white light by prismatic refraction, as effected by Sir Isaac Newton, has, for more than a hundred and fifty years, been received as a demonstrated truth by the most distinguished philosophers of all nations. Various attempts indeed have been made, both in his day and in ours, to overturn this beautiful generalization, but they have been made by persons not only ignorant of the subject, but unacquainted with the first principles of physical research.

The analysis of light by the prism is perfect, in so far as it goes, and was demonstrated by Newton in the case of spectra produced by the single refracting medium which he employed. It was left, indeed, to his successors to discover the different dispersive powers of bodies, and the irrationality of the coloured spaces, and thus to establish the principles of the Achromatic and the Aplanatic Telescopes. These discoveries presented no points of objection to the views of Newton. They were entirely of a supplementary character, and were calculated to establish more firmly his general doctrine respecting the composition of light.

It is a familiar experience for the teacher in charge of a class dissecting Rana temporaria to notice or have his attention directed to blood-vessels in an abnormal position or absent from the place where they were expected. Sometimes, perhaps too frequently, they are ignored; but they are of interest, not only in themselves, but also because they throw light on problems that have arisen in other lines of work. From time to time such abnormalities have been reported in R. temporaria and in other Anura, but the literature of the subject is scattered in different journals.

A brief account of the stratigraphy of the Westphalian (Upper Carboniferous) of the Ayrshire Coalfield is given. Older rocks are found to be overlain by Westphalian strata of differing age in various parts of the coalfield. A correlation of the coal seams known by numerous local names in various areas of the coalfield is shown. The vertical distribution of species of non-marine bivalves is illustrated and the faunas associated with various horizons discussed. The presence of variants of Anthraconaia pulchella Broadhurst at more than one horizon is noted. The lateral distribution of species at given horizons is examined and it is shown that elements of the overall fauna of an horizon may be absent in parts of the coalfield. The occurrence of marine bands in the succession is noted and their distribution discussed. It is suggested that during the Aegiranum Marine Band incursion the northern and north-western parts of the coalfield were nearer a land mass. A new stratigraphical name, the Bogton Marine Band is proposed. The band occurs within the Upper Similis-Pulchra Chronozone.

Isle of Wight disease is, as we have seen, primarily a disease of the respiratory system, in which the organism remains localised throughout the entire course of the attack.

The effects are, however, far-reaching, and are registered in the disordered functioning of several organs, and in visible pathological changes in some of them.

The parasitic invasion has two aspects.

We have, in the first place, to consider the active injury wrought upon the host by a parasite developing and living at the expense of its body fluids. With this aspect of the question may be coupled the possibility of a definite toxic action on the part of the parasite.

In the second place, we have to consider the passive rôle of the mites in hindering or inhibiting the normal functions of the infected organs.

Before proceeding to consider the various pathological conditions, a few words on the distribution of the parasite within the host is called for.

The theory of reciprocal figures used as diagrams of forces was first completely stated by Professor T. Clerk Maxwell, in a paper published in the “Philosophical Magazine,” April 1864. The following definition of reciprocal plane figures, and their application to statics, are there given as follows:—

“Two plane figures are reciprocal when they consist of an equal number of lines, so that corresponding lines in the two figures are parallel, and corresponding lines which converge to a point in one figure form a closed polygon in the other.”

“If forces represented in magnitude by two lines of a figure be made to act between the extremities of the corresponding lines of the reciprocal figure, then the points of the reciprocal figure will all be in equilibrium under the action of these forces.”

The demonstration of this statement is given. The conditions under which stresses are determinate, and some examples of reciprocal figures, are also given in the paper, which leaves nothing to be desired by the mathematician.

Quaternary deposits and landforms are an integral component of Scotland's geodiversity and natural heritage with intrinsic, scientific, educational, cultural, aesthetic and ecological values. Their conservation is founded on the assessment and safeguard of key protected areas principally for their scientific values. The evaluation of site networks for Quaternary deposits and landforms (including glacial, fluvial, coastal, mass movement, karst and cave features) has evolved since the late 1940s, culminating in the Great Britain Geological Conservation Review (GCR) site assessments undertaken principally between 1977 and the early 1990s. Significant scientific progress since then has arisen, for example, from re-investigation of existing sites and discoveries of new sites, developments in geochronology and the formulation and application of new concepts and models. Both the GCR site lists and the supporting site documentation now require updating in the light of this progress. Today there is greater emphasis on the wider, non-scientific values of geoconservation including, for example, on ecosystem services, links with biodiversity and cultural heritage, geotourism and the benefits for human health and wellbeing through improved understanding of dynamic landscapes, climate change and natural hazards. Involvement of wider public support beyond the geoscience community and fostering better integration of geoheritage within the developing nature conservation agenda, including a land systems approach, protected area planning and management, natural capital and connecting people and nature, will help further to protect our Quaternary geoheritage.

Latest Eocene fossil plant remains occur in concentrations within blue-grey micrite known as Insect Limestone near the base of the Bembridge Marls Member (Bouldnor Formation, Solent Group), Isle of Wight, southern England. Some of the previously reported taxa (collections in the Natural History Museum, London) are not preserved within the Insect Limestone. These (e.g., all Arecaceae (palms)) are excluded from the floral list. New non-destructive techniques have yielded additional taxonomic information. Leaves previously assigned to Ficus and Fagus are now incertae sedis. Wetland elements are abundant, particularly Typha, but also Acrostichum, Azolla, Potamogeton, Sparganium and others. Non-wetland elements are rare. Trees and shrubs included representatives of Betulaceae, Caprifoliaceae, Juglandaceae, Lauraceae, Rhamnaceae (the sclerophyllous Zizyphus), other flowering plants and several genera of conifers. There are rare specimens of possible herbaceous plants and propagules with plumes or awns, the latter possibly an early fossil record of Clematis. The common plant remains were probably derived from vegetation near a freshwater body, sometimes with slight brackish influence, whilst rarer elements were probably blown in from a greater distance. There is little evidence of plant–insect interaction; one leaf with small galls, a stem containing an insect larva and a possible association between stratiomyid flies and Typha.

The reconstructed palate of Whatcheeria deltae indicates a skull that was unusually narrow: at least 2.2 times longer than wide if the pterygoids are conservatively placed in the horizontal plane. This maximum width is narrower than any other early tetrapod reconstructed so far. Rotating the pterygoids to produce a vaulted palate would produce an even narrower skull. Primitive palatal features include very narrow interpterygoid vacuities and a vomer, palatine, and ectopterygoid with fang-sized replacement pairs. It is derived in that there is no anterior palatal fenestra and the premaxilla has a substantial palatal shelf – a combination of characters shared only with Proterogyrinus among early tetrapods. There is a possible septomaxilla in one specimen. Whatcheeria differs from and is more derived than Pederpes, its likely sister taxon, in that only the pterygoid is covered with denticles, the vomer, palatine, and ectopterygoid containing labyrinthine teeth only. Reconstructed dental occlusion indicates that the large choana apparently accommodated the large dentary fangs; this would be a unique feature among early tetrapods. The palatal ramus of the pterygoid is longer than the quadrate ramus, which does not have a descending flange. Like Meckel's cartilage in the lower jaw, the palatoquadrate is fully ossified in larger specimens, such that in a posterior view of the skull the pterygoid is mostly hidden from sight by the epipterygoid. The ossified neurocranium consists of the basiparasphenoid and basioccipital; no ossified sphenethmoid has been found. Remains of otic capsules are partial, crushed, and smeared, so no useful morphology is available. The stapes appears to be more columnar and less plate-like than in many other primitive, early tetrapods.

A review is presented of the genera and species, both living and fossil, comprising the Superfamily Kraussinoidea and of their geographic and stratigraphic distributions. Two new fossil species are described, Kraussina chilensis and Megerlina miracula, from the Miocene of Chile and New Zealand respectively. The ontogenetic development of the brachidium in each of the four kraussinid genera is described and on the basis of recognised differences it is proposed that a new taxonomic subdivision is made that places Megerlia in a new subfamily Megerliinae, distinct from the other three genera in the existing subfamily Kraussininae Dall. The loop ontogeny of kraussinoids is compared with that of other terebratellidines and a phylogenetic linkage between kraussinoids and laqueoids is suggested.

Zavitokichnus fusiformis n. igen. et n. isp. occurs in Lower Cretaceous (Valanginian to Hauterivian) limestones of the Fatric Superunit in the Western Carpathians. Typical cross sections of this more or less spiral trace fossil are sometimes U–O–C–S-shaped. In cross-section the trace fossil passes from a simple linear form, and spreads to a wider rolled-up or rolled-out form and then it returns to a linear trace. Spreite-like lamellae are distinguishable on several cross-section examples. The trace fossil was produced by a deposit feeder and it might be classified as a fodinichnion. Z. fusiformis co-occurs with trace fossil associations of Zoophycos, Chondrites, Planolites, Hormosiroidea and Palaeophycus in carbonate sediments of a deep-seated ramp along the margin of the Fatric intrashelf basin.

The development of D. (Didymograptus) murchisoni (Beck), the type species of the genus, is shown to be unequivocally of anus type, with thl1 dicalyal and a low metasicular origin of thl1. An evolutionary line from the early, Arenig, bifidus group is supported; and clear distinctions are drawn between the subgenera D. (Didymograptus), D. (Didymograptellus) and D. (Jenkinsograptus), the first of these being redefined. The range of variation of biocharacters of D. murchisoni is analysed using exquisitely preserved undeformed material from Saudi Arabia, and comparisons are made with the undeformed type material, and with undeformed (nodule) collections from Abereiddy Bay, Pembrokeshire. The astogenetically late developments of D. murchisoni are described.

The collection of echinoids, which is the subject of this report, was made by Mr R. A. Farquharson, M.A., M.Sc., F.G.S., Government Geologist, during his survey of British Somaliland in the year 1923–24. The collection was presented by the Colonial Office to the Geological Department of the British Museum, and the Keeper, Dr F. A. Bather, F.R.S., has been good enough to allow me to examine and describe these interesting specimens. I have been fortunate in having beside me for comparison the echinoids from Somaliland in the Hunterian Museum, which were collected by Mr B. K. N. Wyllie, B.Sc., F.G.S., and Dr W. E. Smellie, and through them presented by the Anglo-Persian Oil Company. I take this opportunity of expressing my thanks to Professor Gregory for his interest in the collection and for much kind help.

For a long time I was anxious to know the rate of expansion of the common building-stone of this neighbourhood, as it is not given in any of the tables of the expansions of substances, because I have sometimes thought that the vertical cracks frequently seen intersecting rubble walls might arise from the contraction caused by a diminution of temperature. During a long-continued and severe frost which occurred in 1826, I thought the rents in a considerable stretch of wall, which I passed at all seasons, appeared more open than usual. This, however, was merely conjectural, and I paid no more attention to the subject until 1830, when, as I mentioned in a notice on the commencement of my experiments read at the meeting of the British Association in September last, an interdict of the Dean of Guild Court of Edinburgh rendered the rate of expansion of stone a matter of more importance than merely a curious philosophical speculation.

There is an important geometrical problem which proposes to find a curve having a given relation to a series of curves described according to a given law. This is the problem of Trajectories in its general form.

The series of curves is obtained from the general equation to a curve by the variation of its parameters. In the general case, this variation may change the form of the curve, but, in the case which we are about to consider, the curve is changed only in position.

This change of position takes place partly by rotation, and partly by transference through space. The rolling of one curve on another is an example of this compound motion.

Air photo interpretation and geochemistry have been used to supplement sparse field data in compiling a reconnaissance geological map of the area around the Lecht. Upper Appin and lower Argyll Group rocks are exposed, the best marker horizons being correlatives of the Appin and Jura Quartzites. Scatter plots, Q mode factor analysis and Pearson correlation coefficients of geochemical data were successfully used in the correlation of the pelite and limestone outcrops. The presence of major recumbent folds is inferred. The area is cut by numerous minor faults which are thought to be related to a major transcurrent fault, the probable north-eastern continuation of the Loch Tay fault, which was active in Lower Old Red Sandstone times.

The Lecht manganiferous ironstone is a seepage-bog ore type deposit derived by weathering of the local Dalradian sequence. Despite intensive leaching, this sequence still shows anomalously high levels of several elements, particularly Mn, Ba and Zn. In addition, stratiform sphalerite and manganiferous garnet are present in Blair Atholl Subgroup limestone and pelite horizons, respectively. Mineralogical and geochemical evidence suggests the presence of Zn–Pb–(Ag)–(?Au) exhalative mineralisation within the upper Appin Group Dalradian of the region, of which the Lecht represents the distal manganiferous expression.

The first instalment of this paper was devoted in great part to the general subject involved in its title, but many of the illustrations were derived from the special case of the flight of a golf-ball. Since it was read I have endeavoured, alike by observation and by experiment, to improve my numerical data for this interesting application, particularly as regards the important question of the coefficient of resistance of the air. As will be seen, I now find a value intermediate to those derived (by taking average estimates of the mass and diameter of a golf-ball) from the results of Robins and of Bashforth. This has been obtained indirectly by means of a considerable improvement in the apparatus by which I had attempted to measure the initial speed of a golf-ball. I have, still, little doubt that the speed may, occasionally, amount to the 300, or perhaps even the 350, foot-seconds which I assumed provisionally in my former paper:—but even the first of these is a somewhat extravagant estimate; and I am now of opinion that, even with very good driving, an initial speed of about 240 is not often an underestimate, at least in careful play. From this, and the fact that six seconds at least are required for a long carry (say 180 yards), I reckon the “terminal velocity” at about 108, giving v2/360 as the resistance-acceleration.

In order to determine with exactitude the movements made by the wings in flight, and the part which the air plays in modifying them, I was induced several years ago to collect a large number of facts, and to undertake an extensive series of experiments with natural and artificial wings. My observations and experiments, I may remark, were not wholly confined to flight. On the contrary, I traced the analogy between flying, swimming, and walking; a circumstance which compelled me to pay particular attention to the size, shape, and movements, not only of wings, but also of the travelling surfaces of quadrupeds, amphibia, and fishes. By adopting this method, I obtained suggestions which have proved of the utmost importance to me in my attempts at elucidating the very intricate problem of flight.

Rowleya trifurcata gen. et sp. nov. is described from specimens discovered in coal-balls from the Union Mine of Burnley, Lancashire. It consists of slender cylindrical axes (0·3–1·4 mm diam.) branched at long intervals by anisotomous dichotomies. Often three closely consecutive dichotomies produce a lateral trifurcation in which one or both outer branches have been arrested in growth. These bear one or two pairs of vascularised tapering appendages interpreted as ‘leaves’. Main axes usually possess a tetrarch solid strand of primary xylem somewhat like certain branches of Stauropteris. Slightly smaller axes often have a triarch strand of primary xylem triangular in cross-section. Backwardly directed branches are occasionally borne above a trifurcation and opposite a pair of ‘leaves’.

Rowleya trifurcata is associated with Psalixochlaena cylindrica and Botryopteris hirsuta. Its closest affinities seem to be with Stauropteris and Psilotum.

The influence of compression and dilatation in producing the doubly refracting structure in solids of all kinds, whether crystallised or uncrystallised, which do not possess it, and in modifying that structure in all crystals which do possess it, has been long known; but with this class of phenomena, those which I am about to describe have no connection whatever.

In the course of experiments on the double reflexion and polarisation of light which I discovered in the chrysammates of potash and magnesia, murexide, and other crystals, I was surprised to find that these substances could be spread out upon glass by hard pressure, like grease or soft wax, and that in the case of chrysammate of potash and other bodies, when the powder could scarcely be distinguished from snuff, I obtained a transparent film, exhibiting the phenomena of double reflexion and polarisation from its surface, as perfectly as if I had been using a large crystal.

Multidisciplinary three-dimensional modelling, involving geophysical, structural and geochemical data, has been used to study the relationships between magmatism, tectonics, fluid circulation and mineralisation in the northern Limousin, and to provide P-T-Z-t paths constrained by the available dating. The ore deposit occurrence displays little spatial relationship with granites emplaced in the 360-320 Ma period, probably because the low global permeability and tectonic regime did not allowed vertical fluid exchanges to be established. In contrast, the change in the tectonic regime induced by the delamination of the lower lithosphere (320-300 Ma), and characterised by the passage to general extension, has played a major metallogenic role. However, the ore deposit processes appear to be specific to each metal. Most of the W-Sn deposits appear to be synchronous with rare metal granites emplacement, at c. 310 Ma, that allowed the focus of fluids of different origins towards the apex of plutons. In contrast, for Au and U, the whole mineralisation process covers several tens of-millions of years. It is controlled by the regional tectonic evolution of the Limousin area during the same period, and especially by a rapid exhumation of the ductile crust which occurred in the 310-300 Ma period.