ALBERT

Notes: Spurious reflections showing a residual move-out are generally present on both corrected seismic cross-sections and common depth point composites.We propose to determine a space-time filter satisfying the following conditions: to attenuate as much as possible reflections presenting a given move-out, to retain intact reflections whose time gradient is zero (or has a predetermined value), to be applicable efficiently even to a small number of traces, not to amplify random noise unduly.After briefly indicating the design principle of these filters, we shall give the results of their application to the theoretical examples, in order to bring out: the influence of sampling interval and filter length (possibility of achieving efficient filtering using an apparatus with a small number of terms), the effect of filtering on dipping reflections (reduction in amplitude and distortion increasing with the time gradient), the range of reflection move-out that can effectively be filtered with the same apparatus, the disturbing influence of random noise.〈section xml:id="abs1-2"〉〈title type="main"〉RESUMEOn constate généralement, tant sur les films sismiques corrigés que sur les résultats de couverture multiple, la présence de réflexions parasites présentant une courbure résiduelle d'indicatrice.Nous nous sommes proposé de déterminer un opérateur de filtrage spatio-temporel satisfaisant aux conditions suivantes: filtrer le plus possible les réflexions présentant une courbure donnée, conserver intégralement les réflexions dont le gradient temps est nul (ou a une valeur déterminée), pourvoir être appliqué efficacement à un petit nombre de traces, ne pas amplifier outre mesure les bruits inorganicés.Après avoir indiqué brièvement le principe du calcul de ces filtres, nous présenterons les résultats de leur application à des exemples théoriques, afin de mettre en évidence:ľ'influence du pas d'échantillonnage et de la longueur du filtre (possibilityé d'obtenir un filtrage efficace avec un opérateur comportant un petit nombre de termes),ľ'effet du filtrage sur les réflexions pentées (réduction d'amplitude et distorsion croissant avec le gradient temps),ľ'ouverture de ľ'éventail des réflexions courbes que ľ'on peut filtrer efficacement avec un même opérateur,ľ'influence perturbatrice de bruits inorganicés.

Notes: The effects were studied of nitrogen and phosphorus fertilizers on the production of perennial ryegrass at high altitudes in Kenya. N had little influence on production during establishment but increased it markedly during the second and third years. The effect of P was less and was related to the amount of N applied. The response to applied N in terms of dry matter production, and the recovery of the N applied, compared favourably with data from trials elsewhere. It is apparent from the results that temperate grasses can be productive at high altitudes in Kenya and provide a considerable potential for pasture production.

Notes: As a preliminary step in the development of improved bred varieties an examination has been made of the factors which contribute to the success or failure of white clover (Trifolium repens) in hill land reseeding. Severe restrictions are placed on clover performance and N fixation in many hill areas in Britain by the poor climate, the low pH and exchangeable base status of the soils and the low frequency of effective indigenous Rhizobium strains.Agronomic solutions to some of these problems exist, but experience in mid-Wales suggests the need for new bred varieties with improved adaptation to the prevailing conditions, particular attention being directed to the limitation of N fixation by low soil temperature.

Notes: The auto-correlation function of a seismic trace contains information on all the multiple reflection activity present in the trace.The interpretation of this information is facilitated by the arrangement of autocorrelation functions in cross-sectional form, in the manner of a normal record section. This is the concept of the Sectional Auto-Correlogram.Specifically, the Sectional Auto-Correlogram will…Show if the record section does not include significant multiples, thus allowing confident picking of the primary reflections.Show if the record section does include significant multiples, giving their travel times and inclinations (and, under certain circumstances, their reflection coefficients).Indicate by what process the multiples should be treated.Yield an authoritative measure of the success of a multiple-attenuating treatment.Delineate shallow horizons, even those whose primary reflections are too early to be recorded satisfactorily.Give the true travel time of a primary reflector, and the sign of its reflection coefficient.The Sectional Auto-Correlogram allows the study of primary reflectors by consideration of the multiples generated by them, and in this sense may be said to turn multiple reflections to advantage. Thus a primary reflection at a certain time is defined if we find that every reflection on the record is followed by a multiple after this certain time. Alternatively, a primary reflection at a certain time is defined if, after that certain time, we can find a repetition of the entire record.The Sectional Auto-Correlogram also has secondary uses in fault identification, crustal studies and weathering problems.

Notes: The development of optically pumped and monitored “atomic” magnetometers has allowed the application of greater resolution in geomagnetic measurements for exploration purposes. This paper presents a survey of instrumentation in use, the variety of exploration techniques that are being used in practice, and an estimate of their state of development.Alkali metals (rubidium and cesium) and helium have been used as active elements to obtain the magnetic-field dependent Larmor frequency. Each of these instruments is capable of obtaining high resolution data (data with sensitivity numerically smaller than one-tenth gamma). They have been adapted for airborne, land, and marine usage.Such sensitivity has enabled the rapid development of geomagnetic gradiometers, high sensitivity aeromagnetics, diurnally reduced ground surveys, broad-band magneto-telluric surveys, susceptibility measurements, and convenient magnetic search and location techniques. Outlines of each procedure and an example of its application are given.

Notes: The common depth point method of shooting in oil exploration provides a series of seismic traces which yield information about the substrata layers at one location. After normal moveout and static corrections have been applied, the traces are combined by horizontal stacking, or linear multichannel filtering, into a single record in which the primary reflections have been enhanced relative to the multiple reflections and random noise.The criterion used in optimum horizontal stacking is to maximize the signal to noise power ratio, where signal refers to the primary reflection sequence and noise includes the multiple reflections. It is shown when this criterion is equivalent to minimizing the mean square difference between the desired signal (primary reflection sequence) and the weighted horizontally stacked traces.If the seismic traces are combined by multichannel linear filtering, the primary reflection sequence will have undergone some phase and frequency distortion on the resulting record. The signal to noise power ratio then becomes less meaningful a criterion for designing the optimum linear multichannel filter, and the mean square criterion is adopted. In general, however, since more a priori information about the seismic traces is required to design the optimum linear multichannel filter than required for the optimum set of weights of the horizontal stacking process, the former will be an improvement over the latter. It becomes evident that optimum horizontal stacking is a restricted form of linear multichannel filtering.

Notes: Book review in this articleW. L. RUSSELL, Principles of Petroleum Geology, McGraw-Hill Publishing Company

Notes: Formulae of the energy spectrum and autocorrelation function have been derived for magnetic anomalies due to four classes of bodies which can be represented in turn by (a) poles, (b) line of poles, (c) dipoles and (d) line of dipoles. The effects of the depth and dimensions of the magnetized sources on the spectrum and the autocorrelation function have been studied. In the case of the dipole models, the orientation of the polarization vector casts a significant influence on the characteristics of the two functions. In all cases, however, the functions change in size and shape as the inclination and declination of the geomagnetic vector are varied.

Notes: The derivation and application of a new method of geomagnetic deep sounding, that is exploring for underground electrical conductivity anomalies by means of temporal variations of the earth's magnetic field, is presented.The problem is restricted to two dimensions (horizontal and vertical) and for the case of a nearly homogeneous horizontal component of the disturbance vector as compared with the vertical over the area in question.The basis of the method is a relationship between both components of the disturbance vector. The first step is a period analysis of the records and from this the construction of so called “characteristic functions”, one for each station, these functions being determined by the conductivity distribution of the earth's interior. The second step consists of a model interpretation of these functions.The method is applied to simultaneous records from five stations (U. Schmucker, 1959) within the region of the conductivity-anomaly of Northern Germany. A preliminary model of this anomaly is given.

Notes: The screening effect of thin, relatively shallow high-velocity layers often presents considerable problems in seismic exploration. Such layers prevent the greater part of the seismic energy from travelling to greater depths and introduce additional refraction arrivals, confusing the seismogram still further.In order to investigate both the screening and refractive properties of high-velocity layers, scale-model experiments have been made over a wide range of layer-thickness/ wavelength ratios (0.05 〈 d/λ 〈 2) for suitably chosen material contrasts. The results may be summarised as follows.Refraction arrivals from thin layers in the field may be recognised by their relatively rapid amplitude decay. Furthermore, the “echeloning”-effect observed for refraction first arrivals may be due to the presence of a (thin) layered structure. Since the apparent refraction velocity varies with d/λ when d/λ 〈 1, differences between vertical well-log velocities and velocities observed along the surface may be expected, making time/depth conversion using surface velocity data inaccurate.Transmission of elastic energy may be expected, if anywhere, only near the shotpoint, at small geophone offset, and for relatively thin screens (d/λ 〈 0.1). The transmitted signal shape is then independent of the layer thickness. This transmitted energy may be registered either in a reflection set-up with geophones near the shotpoint, or in long-distance refraction work.Three possibilities are offered for overcoming the screening effect of thin high-velocity layers: Use longer-wavelength signalsApply short-spread reflection shootingApply long-distance refraction shootingThe experimental results obtained in scale-model arrangements of such set-ups confirm the potentialities of these methods.

Notes: From travel time observations on a test profile ranging from o to 145 km four main events can be distinguished. They represent reflections and diving waves from various discontinuities within the earth crust. A low-velocity zone of a few kilometres thickness begins at a depth of about 10 km, another one probably at 25 km.For the MohoričIć discontinuity (=MD) a gradient zone with a large velocity gradient instead of a first order interface is postulated in order to explain some irregularities of the travel time curve. Comparisons between the to-time of the MD with the statistical data from Dohr and Liebscher show an excellent correlation.〈section xml:id="abs1-2"〉〈title type="main"〉ZusammenfassungAufgrund von Laufzeitbeobachtungen eines Weitwinkelprofils in der Bayrischen Molasse von o bis 145 km Länge können im wesentlichen vier verschiedene Einsätze unterschieden werden, die sich aus Reflexionen bzw. aus Tauchwellen zusammensetzen. Eine Zone geringerer Geschwindigkeit beginnt bei etwa 10 km Tiefe. eine weitere liegt wahr-scheinlich unterhalb 25 km Tiefe. Von den Unregelmäßigkeiten der Laufzeitkurve der MohorovičIć-Diskontinuität (=MD) wird eine Zone mit einem starken Geschwindigkeits-gradienten anstelle einer “scharfen” Grenzfläche abgeleitet. Vergleiche zwischen der to- Zeit der MD-Reflexionskurve mit den statistischen Untersuchungen von Dohr und Liebscher zeigen eine sehr gute Übereinstimmung.

Notes: This paper gives a report about experiments with the geomagnetic field-balance with ribbon suspension of the FANSELAU-type under extreme climatic conditions. These experiments were carried out by several institutions. The results show that the field balances “H” and “Z” give right records even under extreme conditions.

Notes: The design and construction of hydroelectric works, and more particularly of storage reservoirs and dams, in karst areas pose extremely varied and complex engineering, geological and hydrogeological problems, for the solution of which no widely applied techniques have yet been developed.In addition to conventional geological and hydrogeological methods for the study of karst phenomena, the application of more efficient methods of a primarily geophysical nature is called for. These methods, which provide the best means for solving the complex problems encountered in karst, are steadily gaining acceptance.The Miruše storage reservoir and the Grančarevo dam are the key structures in the Trebišnjica hydroelectric complex and are located in an area of typical Dinaric karst. Many of the engineering, geological and hydrogeological problems connected with their design and construction were solved with the aid of electrical geophysical prospecting methods (especially the resistivity method). The investigations provided data on the depth of karstification (the relief of the base level of karst erosion), the position of intensively karstified and tectonically broken zones, as well as on the general orientation of the process of karstification. All these data were helpful in providing a more accurate insight into the impermeability of the rocks that formed the storage reservoir (in relation to the proposed impounding level); they also enabled the consolidation structures (impervious curtains), aimed at preventing excessive losses due to seepage, to be designed more economically.

Notes: An experiment is described in which uneven grazing by sheep introduced a bias in a white clover variety trial. The data were adjusted by covariance, using as the independent variable the position of the plots within the paddocks.Attention is drawn to the errors that may result from uneven grazing and a comparison is made with errors due to transference of fertility. Means of avoiding similar occurrences are suggested.

Notes: In a sward sown to Lolium perenne and Trifolium repens measurements were made of the yield and quality of dry matter which was on offer for grazing, or for cutting to be ensiled. In order to follow, within a system of fat lamb production, the potential for an increase or decrease in the DM yield from year to year, a record was also required of the amount of this DM which was eaten by the grazing sheep. The results show that in grazed swards at 2 stocking rates the DM of the sward present per unit area increased during the course of the experiment. This increase, however, was not harvested by the animals. A great deal more DM was harvested in the first year by the animals at the lower stocking rate than was harvested in the following years at this rate or in any year at the higher rate of stocking. There was a greater difference between the values for the digestibility of organic-matter immediately before grazing and those immediately afterwards in the first year at the lower stocking rate than in the following years, or in any year at the higher rate of stocking. In cut swards there was no evidence of a progressive decrease in production from year to year.

Notes: Book reviewed in the article:EXPERIMENTAL HUSBANDRY FARMS AND EXPERIMENTAL HORTICULTURE STATIONSBURG P. F. J. van, ARNOLD, G. H. [Eds] Nitrogen and grassland

Notes: An experiment is described in which timothy, grown for production of seed, was cut once annually on dates ranging from 23 October to 24 May. New tillers in selected plants were labelled at monthly intervals during autumn and winter for 2 years, to determine the pattern of production of tillers and to assess the reproductive development of categories of tillers. The majority of tillers were produced in autumn, but production was continuous throughout the winter. There was a big increase from the first to the second year in the total number of tillers produced, but neither the pattern nor amount of tiller production was affected by cutting. The % of fertile tillers was highest in the oldest tillers, and was affected little by the increase in the number of tillers from the first to the second year; cutting had little effect on the % fertility except where floral primordia were removed by the cut on 24 May. In all treatments at least 90% of the ears at harvest were produced by tillers initiated the previous autumn. The penetration of light to the base of the plants was increased considerably by cutting, but it is concluded that interception of light by the whole plant is more beneficial than an increase in the penetration of light into the plant and a concomitant reduction in the total interception of light by the plant.

Notes: An experiment was designed to compare morphological development, light interception and time interval as possible criteria for the defoliation of timothy, brome-grass and cocksfoot. The morphological criterion included: (a) a first harvest before stem elongation and a second harvest after initiation of axillary bud development at the base of each tiller (b) a harvest immediately after stem elongation. Light was compared on the basis of 95 % and 80 % interception of the incident radiation by the foliage. Two-, 4- and 6-week intervals were used in the time series. Increased yields of up to 2600 lb DM/ac were obtained in timothy and bromegrass fertilized at 275 lb N/ac/yr when morphological treatment (a) was used in preference to (b); cocksfoot yields were not influenced. The greater the time interval between harvests or the greater the light interception before harvest, the greater was the yield. Advantages and disadvantages of the 3 criteria are discussed.

Notes: A crop physiologist's approach to some problems of grassland research, with particular reference to terminology and the sown sward.

Notes: An experiment is described in which nitrogen was applied in relation to the physiological stage of development in cocksfoot grown for seed. All applications of N increased the yield of seed, but applying all the N during the phase of autumnal tillering was less effective than applying it at stages of development in spring (beginning of vernal growth, initiation of inflorescences, complete differentiation of inflorescences), or in autumn and spring, because of a decrease in the number of tillers which survived to flower in the following year. Differences due to the stage of development at which N was applied in spring were small. Primary effects of N were to increase the number of tillers and ears per plant, and to accelerate the rate of development of inflorescences; in addition, N advanced the date of initiation of inflorescences without similarly advancing the date of complete differentiation of inflorescences. It is concluded that a long period between the initiation and complete differentiation of the inflorescence is conducive to high yields of seed.

Notes: Experiments were conducted to analyse the effect of 3-year-old grass plots, under a cut-and-carry system, on the yields of maize and groundnut crops, and at the same time to compare the relative importance of the water-stable aggregates and the nitrogen status of the soil. The N reserves, organic carbon and water-stable aggregate contents of soils were higher under grass plots than in the ploughed-up-fallow plots. Maize yields showed a close correlation with total soil N, mineralized N after incubation for 20 days, and water-stable aggregate contents; groundnut yields showed close correlation only with water-stable aggregates. The effects of the variations in soil N and in the water-stable aggregate content of the soil on the yields of maize and groundnuts were examined by multiple regression analysis of data from a large number of plots.

Notes: The effect of cocksfoot streak virus (CSV) on Dactylis glomerata L. and barley yellowdwarf virus (BYDV) on Lolium perenne L. was investigated under both single-plant and simulated-sward conditions. The effect of cocksfoot mottle (CFMV) was examined on single plants. CFMV was lethal, and in conditions of inter-plant competition CSV was semi-lethal and BYDV was non-lethal. When the virus was lethal, a considerable lag-phase was observed between mortality and complete compensation in yield. When the virus was non-lethal, plant growth was restricted, either horizontally (CSV) or vertically (BYDV). In mixed, healthy and infected plant populations healthy individuals compensated only for reductions in lateral growth.CSV infection transformed plants of a pasture variety into ‘hay’ types and BYDV infection transformed plants of a hay variety into ‘pasture’ types. CSV increased the plant's aggressiveness in hay conditions, but reduced its ability to withstand frequent defoliation. Conversely, BYDV increased the plant's aggressiveness in pasture conditions, but reduced it in hay conditions. Compensation from healthy plants occurred only in CSV-infected swards subjected to frequent defoliation. Some possible reasons for the absence of compensation in other treatments are discussed.

Notes: Irrigated lucerne/grass mixtures were treated with annual applications of N-P fertilizers to determine the extent of control of lucerne domination. Eighty pounds of N with or without associated P sustained the grass components at an acceptable level and increased yields, which were constituted of 2 parts grass for each 3 parts of legume. Where no fertilizer, or P fertilizer only, was used the hay harvested was composed of only 1 part grass for each 8 or 9 parts of lucerne. Lucerne to grass seed-ratio manipulation did not influence botanical composition nor did it affect fertilizer influence.

Notes: A procedure and equipment which make possible a continuous output of 250 to 300 determinations of in vitro digestibility of organic matter per week are described.The effect on in vitro digestibility values of removing rumen liquor from sheep at various times before and after feeding, mixing of rumen liquors from different sheep, and nitrogen supplementation of the inoculum are investigated. Results are given of a comparison of the effect of soil contamination on in vitro data when expressed as digestibility of dry matter and digestibility of organic matter. The levels of within and between-batch errors are stated and the accuracy of prediction of feeding value is discussed.

Notes: The present and potential land use of rough hill pastures in Brecknockshire has been investigated. The interests of the Brecon Beacons National Park, reservoir, Forestry Commission and commonland need not compete, but could be complementary. Areas containing a high proportion of the podzolized soils carry the most nutritious pastures, rich in Agrostis and Vaccinium, and agreement amongst the commoners could ensure they are grazed to the limit of their productivity. In the absence of afforestation, the grazing of superior pastures around the peaks of the Fforest Fawr-Brecon Beacons range is consistent with the interests of both the National Park and reservoir authorities, although the erosion hazard is greater. The S. and E. directed spurs of Drygarn, the N. E. plateau of Mynydd Eppynt and the S. W. flanks of the Black Mountains have similarly productive hill pastures. Areas such as the long back-slopes of the Fforest Fawr-Brecon Beacons range and higher land of Drygarn contain a high proportion of peaty gleyed soils under Molinetum, They provide inferior grazing but support the most productive forests, chiefly of Sitka spruce. By agreement amongst the commoners, where they are known, these areas could be leased to the Forestry Commission for afforestation. However, because common rights are so obscure, prior legislation would probably be necessary. Until their recent destruction, the uplands supported woodland and afforestation of selected areas need not be regarded as incongruous. It would also open up otherwise inaccessible places.

Notes: The grass breeder's approach to the problem of producing new varieties is related to factors controlling sward production. Those factors under the control of the breeder, especially plant type and management, are considered in more detail.It is argued that the methods used by the breeder produce seed of predictable performance when grown under a defined set of conditions-climate, soil and, above all, management. The fate of this ‘improved’ seed is considered in relation to the multitude of seeds mixtures prescribed today. Large imports of seed are made annually into the U. K. but bred strains account for only a low percentage of the herbage seeds used.Some results from Cambridge trials are presented to show the effects on sward production of plant density, seed size, depth of sowing, cutting treatments and the mixing of genotypes. It is suggested that these results point to the frequent misuse of bred strains, both in blending and in the quantity of seed recommended per unit area.The future prospects for herbage breeding are discussed and some novel ideas of cropping mentioned which may, to a limited extent, supplement the use of herbage seeds.

Notes: The results of experiments undertaken in England and New Zealand are reported. Under highly productive pasture a significant correlation was found between pasture production and earthworm numbers and weights. This relationship was not evident until the pastures were more than 3 years old. On pastures of similar total dry-matter production there was a significant correlation between yield of clover and numbers and weights of earthworms. The return of dung by the grazing animal increased earthworm numbers and weights, and the application of nitrogenous fertilizer had a similar but less marked effect. The earthworm population was not demonstrably related to the macro-organic-maller content of the pastures. The grazing of grass-clover pastures was not essential for an increase in earthworm populations to occur. Allolohophora species (mainly A. caliginosa) were dominant under pure grass swards, whereas Lumhricus species (mainly L. rubellus) were dominant under grass/clover swards.

Notes: An increase in the amount of dry-matter recorded from year to year in grazed paddocks was accompanied by changes in the structure and botanical composition of the sward. These changes were due to the presence of the grazing animal, but there was no increase in the amount of DM grazed by the animals. Some increase was harvested when the swards were cut to make silage. Of the 2 possible ways by which organic-matter might circulate within the ecological system, directly from plant to soil or indirectly through the animal, it is suggested that the system of management favoured the former. Since there is evidence that an increase in the amount of DM per unit area implies an increase in the growth potential of the sward, it is concluded that it should be possible to adjust the grazing system to the advantage of the animal population. The development, production and growth of the sward is discussed in ecological and agricultural terms; in the latter, reference is made to the ageing of swards.

Notes: An experiment is described in which cocksfoot, grown for production of seed, was cut annually for 3 years in either autumn, winter or spring. No significant increases in yield of seed/ac were obtained from any treatment compared with an uncut control, and a cut in late April in one year seriously reduced the yield of seed. Additional N applied after a defoliation in October did not increase the yield of seed compared with that from plots which were cut at the same time but not fertilized. The production of tillers was not affected by cutting on any date. The percentage fertility of tillers was increased by cutting in the first year, when the number of tillers was smallest; the fertility was less consistently affected in the second year, and was generally unaffected in the third year. The weight of seed produced per ear was usually reduced by the cutting treatments. In the third year of the experiment it was shown that the penetration of light to the base of the shoots was increased substantially by defoliation, but it is deduced that maximum interception of light by the whole plant is more important for the production of seed than increasing by cutting that proportion which penetrates to the base of the plant.

Notes: Little is known about the possible differential responses to Nitrogen fertilizer in varieties within grass species. Two trials were conducted to study interactions between varieties and level of N. The dry-matter yields of 3 varieties of perennial ryegrass were compared in 4 cuts/yr at 3 levels of N fertilizer. Four cocksfoot varieties under the same cutting management were compared at 2 levels of N. In a total of 20 comparisons, the variety effect was significant on 10 occasions, and the N effect significant in all 20 sets of data. The interaction of variety and N level was significant in only one case suggesting that all varieties in each trial responded similarly to increasing levels of N fertilizer.

Notes: In plant–breeding studies large numbers of samples, often taken from single plants, are assessed for digestibility. A modified in vitro method for such estimations, which has proved accurate and less time-consuming than other methods, is described and results obtained for some grasses are presented.

Notes: Two methods of improving hill land for sheep grazing have been compared on a Festuca/Agrostis pasture in mid-Wales. Ploughing and reseeding, following a pioneer crop, resulted in an excellent sward which remained productive at the end of the 8-year trial period. Surface seeding with light cultivation gave only a fair establishment of white clover, but no sown grass, during the same period. The production and financial results point to the superiority of the former technique where conditions are suitable and where increased grass production can be met by increased sheep stocking. Any worthwhile method must produce real improvement to the herbage.

Notes: Families of Dactytis g/omerata and Lolium perenne derived from ripe inflorescences collected in western France over a range of nearly 7° of latitude were grown at Aberystwyth, 52° N lat. Their growth was examined to determine whether latitude and the habitat of the collected families affected the dates of ear emergence, phml form, and height of the flowering shoots when the grasses were grown at Aberystwyth, Ear emergence was found to be delayed as the latitude of the seed source increased, irrespective of the year of sowing, or, in the case of cocksfoot, irrespective of whether the plants were in their first or second harvest year.Plant growth-form and panicle height were recorded only for the cocksfoots, and the results indicate that they were influenced by habitat and that they reflected the intensity of biotic control that had operated.The families derived from meadows or road verges tended to contain a higher percentage of erect tall types. When, however, the seeds came from grazed orchards or pastures, there were few or no erect plants, but many with a more or less prostrate habit and shorter panicles.

Notes: Physical data, from an experiment to determine the effect of drying on the quality of S48 timothy seed, are used to derive an equation relating the average drying rate of the seed to the temperature and flow of the drying air. The relationship, which can be of use in practical problems, demonstrates the importance of air temperature in determining the drying rate, particularly when compared with similar Jula for wheat.

Notes: Experimental evidence is presented on changes taking place in grass populations during the early stages of sward formation and in older leys. Differentiation which has taken place in ‘permanent’ pastures as a result of agronomic selection pressures is also discussed in relation to the maintenance of pastures.

Notes: The relevant management advantages and disadvantages of the ley and permanent pasture are reviewed. Doubts on the possible long-term effects of soil structure, fertility etc. are discussed from the farmer's point of view.

Notes: Mid–season depression of grassland yield following spring application of N was found to be due almost entirely to clover depression, the grass fraction showing no after effects of the treatment. The effect became more marked and lasted longer in successive years. Varying the date of first defoliation in spring did not affect the clover depression significantly. Possible causes contributing to the depressing effect are discussed.

Notes: The productivity of 2 fertilized sown pasture swards and of a 30-year-old pasture sod was evaluated under rotational and continuous grazing in 1956–62.The application of NP fertilizer (448 kg 11–48–0/ha every 3 years with 112 kg ammonium sulphate in the other years) gave the highest yields of DM and of beef, followed by the P treatment (1120 kg superphosphate/ha). Beef production showed only small responses to either the type of pasture sward, or the method of grazing. Seasonal distribution of beef production was slightly more even on the old sod. For the peak period of June-July, 68% of the gain was made on the old sod against 74% on the cultivated swards under rotational grazing and 79% under continuous grazing. DM/gain ratios were generally higher in wet summers than in dry ones. Conversely, estimated DM digestibility was lowest in wet summers.

Notes: In 2 experiments nitrogenous fertilizer was applied at 3 levels (0, 46 and 92 lb N/ac) to a permanent pasture and a ryegrass/clover ley and the swards were harvested before ear emergence and conserved as either artificially dried grass or tetrapod hay. Apparent dry matter digestibility and voluntary food intake of the conserved herbages were measured with sheep.N caused a small but significant depression in apparent DM digestibility but did not affect voluntary food intake. It increased yields of DM and digestible DM significantly.The DM digestibility and voluntary food intake of hay were always significantly lower than those of the corresponding dried grass. Voluntary food intake of all fodders was directly related to herbage digestibility and inversely related to herbage crude fibre content.

Notes: About half an acre (0·40 ha) of the salt marsh grass Spartina townsendii (s. l.) was cut from a Bristol Channel marsh using a small tractor modified for use on estuarine marshland. The cut grass was ensiled with molasses in a plastic silo.Chemical analyses were carried out on samples of fresh grass and silage. Silage was fed ad libitum to Halfbred × Suffolk wether sheep. Intake, digestibility values and crude protein content were similar to those of medium quality hay.

Notes: Among the many problems of pasture establishment in Rhodesia, those which appear the most serious are: (a) poor seed germination, leading to patchy and weak seedling growth; (b) erratic rainfall, in which heavy storms are followed by hot, dry periods; (c) soil crusting, which forms a surface layer impenetrable from below by the seedling, and from above by rainwater; (d) weed competition, where rank and copious weed growth suppresses establishment of pasture seedlings. Suggestions are made as to how these problems might be overcome.

Notes: Book reviewed in the article:WHITEHEAD, D. C. Nutrient minerals in grassland herbageABRAMS, J. T. [Ed.] Recent advances in animal nutritionMILTHORPE, F. L.; IVINS, J. D. [Eds] The growth of cereals and grasses

Notes: Sorghum almum, Digitaria decumbens and Panicum maximum were fed in fresh, frozen (−20 C) or dried (85° C) form to 21 wethers in metabolism cages. Neither freezing nor drying had a significant (P〉0·05) effect on voluntary intake, dry-matter digestibility or organic-matter digestibility. Drying depressed the apparent digestibility of the nitrogen in all grasses but only in the case of D. decumbens was this significant (P〈0·05). Freezing also depressed the apparent digestibility of N while both freezing and drying reduced N retention, compared with the fresh feed. None of these differences was significant.Freezing and drying are thus methods of pasture preservation that can be used to study the intake and dry-matter digestibility of tropical pastures, but both methods may introduce bias into the measurement of N digestibility and retention.

Notes: Preliminary studies have been undertaken to determine the degree to which diploid and tetraploid ryegrass varieties intercross under field conditions. The results obtained through the use of diploid and tetraploid non-red-base tester plants indicate that pollen from tetraploid ryegrasses constitutes little or no danger to the genetic purity of diploid seed crops, even if grown in close proximity. A small proportion of viable triploid hybrids can arise in the progenies of tetraploid plants heavily exposed to diploid pollen, but here again their frequency and incidence are not of practical consequence.

Notes: Two methods of measuring the liveweight gain of cattle on sown pastures are described in a 15 ac grazing trial. During the first 12 months of grazing, stocking rate was varied within and between pasture species. In the remaining 21 months, stocking rate was maintained at the same level between all pastures, but varied with the overall seasonal changes in grass availability. The relative merits of the two methods are discussed, and it is concluded that the trial using the same stocking rate on all species offered the more effective and practicable method of comparing pasture production differences of the order 30–50%.The results showed significant improvements in liveweight gain in the latter 21 months of the experiment, resulting from the inclusion of a legume, Centrosema pubescens in a Hyparrhenia rufa sward, and from the use of Hyparrhenia rufa rather than Panicum maximum in association with Centrosema pubescens. The ability of unfertilized ley pastures to produce over 300 lb/ac of liveweight gain in favourable years was clearly demonstrated.

Notes: A grazing experiment to measure the feeding values of 4-week-old regrowths of S37 cocksfoot, S23 ryegrass and S24 ryegrass is described. A low grazing pressure was maintained on the pastures to ensure that animal production was not limited by herbage availability. Each sward was grazed by a group of 12 lambs under “worm-free” conditions. Increases in empty body weight, dry body weight and energy were measured by the comparative slaughter technique.The liveweight gain of the cocksfoot-fed lambs was the same as the ryegrass-fed groups during the first half of the experiment but was lower in August and September. The final liveweight gains on S23 and S24 ryegrass were 14% higher than on S37 cocksfoot, but in terms of energy retention S23 ryegrass was 18% and S24 7% better than S37 cocksfoot. Digestibility measurements of herbage cut from the plots being grazed showed a positive correlation with energy retention by the lambs. Energy retention was negatively correlated with the proportion of acetic acid in the rumen adds, a fraction which was itself correlated with the soluble carbohydrate content of the herbage, but not with the digestibility of the herbage.When interpreting animal-production results, intake, digestibility and rumen volatilc-fativ-acid proportions, should be taken into account. Because of the inadequacy of present methods of estimating the herbage intake of grazing animals, measurement of body-energy gains is not justified and empty-liveweight gains are sufficiently precise to measure relative energy retentions at pasture.

Notes: An experiment is described in which the liveweight gains of cattle, grazing different pasture species, were measured when grazing sequences were arranged in the form of a Latin Square. The average coefficient of variation for the 6 “animal” Latin squares used was 28·5%, with a range of 15·1 to 42·6%. Significant improvements in liveweight gain were demonstrated arising from the inclusion of Stylosanthes gracilis in swards of Chloris gayana and Panicum maximum.The problems of conducting and interpreting trials of this type are discussed in relation to the need for data on the economic value of pasture species in the tropics. Latin square grazing designs offer a useful means of measuring animal production from pasture, with the advantage of requiring relatively small numbers of animals in each trial, but trials should be repeated at different sites.

Notes: Further investigation into the value of gillie as a fertilizer for grassland indicates that weather affects responses. Dry weather permits good recovery of gillie N. On the other hand, on dry soil, losses of gillie N by volatilization may be increased if the quantity of sludge applied is insufficient to penetrate the soil. Cow-and-pig gillie may be more efficient than the pure-cow type as a fertilizer, the former being well balanced in N and K, whereas cow gillie requires N supplementation.

Notes: Book reviewed in this article:M. A.F. F. Grass and grasslandSUTTONS GRASS ADVISORY SERVICE. The identification of grasses by the foliage

Notes: The auto-correlation function of a seismic trace contains information on all the multiple reflection activity present in the trace.The interpretation of this information is facilitated by the arrangement of autocorrelation functions in cross-sectional form, in the manner of a normal record section. This is the concept of the Sectional Auto-Correlogram.Specifically, the Sectional Auto-Correlogram will.Show if the record section does not include significant multiples, thus allowing confident picking of the primary reflections.Show if the record section does include significant multiples, giving their travel times and inclinations (and, under certain circumstances, their reflection coefficients).Indicate by what process the multiples should be treated.Yield an authoritative measure of the success of a multiple-attenuating treatment.Delineate shallow horizons, even those whose primary reflections are too early to be recorded satisfactorily.Give the true travel time of a primary reflector, and the sign of its reflection coefficient.The Sectional Auto-Correlogram allows the study of primary reflectors by consideration of the multiples generated by them, and in this sense may be said to turn multiple reflections to advantage. Thus a primary reflection at a certain time is defined if we find that every reflection on the record is followed by a multiple after this certain time. Alternatively, a primary reflection at a certain time is defined if, after that certain time, we can find a repetition of the entire record.The Sectional Auto-Correlogram also has secondary uses in fault identification, crustal studies and weathering problems.

Notes: The development of optically pumped and monitored “atomic” magnetometers has allowed the application of greater resolution in geomagnetic measurements for exploration purposes. This paper presents a survey of instrumentation in use, the variety of exploration techniques that are being used in practice, and an estimate of their state of development.Alkali metals (rubidium and cesium) and helium have been used as active elements to obtain the magnetic-field dependent Larmor frequency. Each of these instruments is capable of obtaining high resolution data (data with sensitivity numerically smaller than one-tenth gamma). They have been adapted for airborne, land, and marine usage.Such sensitivity has enabled the rapid development of geomagnetic gradiometers, high sensitivity aeromagnetics, diurnally reduced ground surveys, broad-band magneto-telluric surveys, susceptibility measurements, and convenient magnetic search and location techniques. Outlines of each procedure and an example of its application are given.〈section xml:id="abs1-2"〉〈title type="main"〉ResumeEn détection des richesses du sol, “les magnétomètres atomiques” qui fonctionnent selon le principe ?un pompage optique ont permis ?obtenir des mesures plus sensibles. Sont décrits les appareillages actuellement utilisés, les méthodes de mesure différentes, ainsi que la situation technique récente.La génération de la fréquence Larmor qui dépend du champ magnétique s'obtient par les métaux alcalins (le rubidium, le césium) et par ľhélium. Chacun des instruments utilisés fournit des résultats de résolution fine, inférieure au dixième du gamma. Des équipements furent réalisés pour ľutilisation aéroportée, sur navire, ainsi que sur terre.De telles sensibilités élevées ont été rendues possibles grâce aux nouveaux gradio-mètres, aux aéro-magnétomètres extra-sensibles, aux mesures des profils terrestres avec correction diurne, aux investigations magnéto-telluriques large bande, aux mesures de susceptibilityé et aux méthodes pratiques de recherche magnétique.Le sommaire explique les principes à la base et les applications de tous ces proédés.

Notes: Downward continuation of the field in the neighborhood of a singularity of a magnetic anomaly is used to render the anomaly more two-dimensional, to make the bottom of the causal body more remote, and to obtain an auxiliary function, φ (O, z), by means of which the anomaly may be interpreted in terms of an equivalent vertical contact or step model. The concept of “apparent depth” is introduced and used in studying depth extent and susceptibility. The methods are illustrated with theoretical and practical examples.

Notes: Refraction along thin high velocity layers and along basement is investigated in two cases.a) high velocity layer just on the basement.b) high velocity layer higher above.Period and attenuation of refracted waves are given as a function of the layer thickness H. Refracted arrivals along thin high velocity layers are visible at significant distances if the layer thickness is not smaller than A/6, where A is the longitudinal wavelength in high velocity medium. the pseudoperiod is proportional to the layer thickness H. The attenuation at large distance follows an x−n e−k1x law, where n is close to I and R1 is inversely proportional to H.Refracted arrivals along the basement are observable even in the case of thin high velocity layers situated in the overburden; their intensity is smaller and their pseudoperiod larger than when no layer exists in the overburden. The intensity of the basement arrival decreases and the pseudoperiod increases with increasing laer thickness.The pseudoperiod and the attenuation of refracted arrival along high velocity layers and along the basement are also highly dependent on acoustic contrasts.Both arrivals from a high velocity layer and from the basement can be recorded simultaneously, provided the frequency spectrum of the seismic cbain is sufficiently broad. IN all cases layer arrivals show a character very different from basement arrivals.〈section xml:id="abs1-2"〉〈title type="main"〉RESUMELa refraction le long des bancs minces rapides et du socle moins rapide sous-jacent, est etudiee sur modeles dans deux cas:a) banc rapide reposant directement sur le socle;b) banc rapide situe plus haut dans le recouvrement.La period et l'attenuation des ondes rerractees sont donnees en fonction den l'epaisseur H du banc rapide. Les arrivees refractees le long des bancs rapides ne sont pas visibles sur une distance importante si l'espaisseur de ces bancs est inferieure a A/6 A designant la longueur d'onde longitudinale dans le milieu rapide. La pseudoperiode est proportionnelle a l'epaisseur H du banc. L'attenuation a grande distance suit une loi eb x−n e−k1x avec n voisin de l et k1 inversement proportionnel a H.Les arrivees refractees le long du socle sont observables en presence de bancs minces rapides dans le recouvrement, mais avec des internsites plus faibles que dans le cas d'unrecouvrement homogene. La pseudoperiode des impulsions refractees du socle augmente avec l'epaisseur H du banc rapide. L'attenuation en fonction de la distance est superieure a l'attenuation observee pour un recouvrement homogene, et elle croit avec H.La pseudo-periode et l'attenuation des arrivees refractees le long des bancs rapides et des marqueurs sous-jacents sont largement fonction des impedances acoustiques des milieux en presence.Les arrivees d'un banc mince rapide et socle peuvent etre observees simultanement a condition que la chaine d'enregistrement ait un spectre en frequence suffisamment large. On constate dans tous les cas que le caractere des arrivees des bancs est tres different du caractere des arrivees du socle.

Notes: The term “structure”, as used here, includes synclinal and anticlinal folds and folding in general, faults, cross fractures and various conditions associated with intrusions. Structure, both regional and local, has a very important role in emplacement of mineralization. Under certain circumstances which occur fairly commonly, structural conditions are reflected significantly in the trends and intensities apparent on aeromagnetic maps. A number of documented illustrations based on Canadian Shield conditions are discussed. Illustrations are drawn from areas of known geology and from proven mining camps, as well as from loci of recent discoveries. Canadian examples are chosen because of existence and availability of extensive aeromagnetic cover, although it is logical to extend the argument to other shields and indeed to regions of other geological, but similar magnetic character.The importance of aeromagnetics in structural approach to exploration and the correctness of such approach seem to be fully substantiated by results discussed.

Notes: The paper describes a transistorised, portable proton precession magnetometer constructed for surface geophysical prospecting. Constructional and circuit details are furnished. The readout of the instrument is digital. The accuracy of measurement is ± 1 part in 20,000. The maximum gradient of the total field under which a satisfactory measurement can be made is about 1 gamma/cm. The sensing head uses a single coil system with distilled water as the proton sample.

Notes: Book review in this articleJ. L. Worzel, Pendulum Gravity Measurements at Sea, John Wiley & Sons, London and New York, 1965, Price 210 sh.D. S. Parasnis, Mining Geophysics, Elsevier Publishing Company, Amsterdam-London-New York, 1966, XVI + 356 pages, 11 tables, 128 illustr., Price N. fls. 50,–.K. Ya. Kondrat'yev, Radiative Heat Exchange in the Atmosphere, Leningrad, English edition, Pergamon Press.

Notes: A brief review of the existing methods of gravity reduction is given and a new method suitable for use on high speed digital computers is described. The method is based on the formula for the gravitational attraction of a frustum of a cone. The topographic contours are represented by polygons and the x and y coordinates of corners of the polygons constitute the input to the computer. The vertical component of the gravitational attraction is calculated by evaluating the cone formula for a number of vertical sections of the topography. Each vertical section is simplified by adopting a procedure of grouping and averaging for the distant points of the section. The effect of the earth's sphericity is taken into account by lowering the distant points of the sections by amounts determined by the curvature. The computations include the area close to the point at which the attraction is required and may be limited to an area defined by a circle centered at this point. The method is therefore compatible with the conventional zone chart methods.As an illustration of the method the gravitational attraction of Caryn Seamount in the Atlantic Ocean is computed. The total Bouguer correction and the Terrain correction are also computed for an area in northwestern South America and comparisons are made with hand computations by a zone chart method. As an example, for work at sea, the Bouguer corrections for an area near the Island of Mauritius in the Indian Ocean are computed and the effects of sphericity and three-dimensionality are calculated.The gravitational attraction of two-dimensional bodies can be computed in a very similar manner. The attraction of the Puerto Rico Trench model is computed and the results are compared with other methods. The effects of sphericity and assumptions involved in extending the models to infinity are discussed.

Notes: A description of planning, organisation and field procedure of a test profile of 150 km length is given. This profile was laid out as an experiment for a detailed investigation of the velocity–depth–structure of the earth's crust in a selected area. The line was to be shot as a wide angle profile with a common reflection point.

Notes: The region of Graus (Central Spanish Pyrenees) has been surveyed by the conventional seismic reflection method in the years 1963–64.This region is strongly accidented and there are only a few roads of access. Thus a good grid of seismic lines could not be realised. Therefore a seismic survey with completely portable equipment was tried out. For that reason drilling was abandoned.The results seem to show that the method of the air-shots is completely comparable with that of buried shots.

Notes: An ill-defined seismic marker has been identified as the top of the sandstone lower Trias in the “Landes”– small area within the whole Aquitaine region for which the S. N. Repal obtained prospecting licences. Before any drilling was made, this marker was thought to belong to the early saliferous triassic series.The quantitative use of the residual gravity anomaly has made the seismic reflection interpretation easier. This interpretation was found to give excellent results along the coastline where all postulated hypothesis proved true in the bore holes of Contis and St Girons.As a first approximation, it appears that the substratum of the saliferous bed in sub-horizontal and has a fairly steady gravity. The Jurassic and the Cretaceous, both limestones, are prevailing (0,15) in comparison with the argillaceous-saliferous Trias and the early Tertiary which was revealed to us with accuracy through seismic surveys. The use of an approximative linear equation where the gravimetric residue is expressed as a function of the limestone thickness allows a better seismic interpretation.This makes possible a more reliable approach of the structural study of post-triassic deposits. The same holds good for the sandstone substratum which shows on an isochronous map strains due to thickness and velocity changes in the overburden. These facts help us to get a better insight into the origin and formation of salt accumulations in this particular area.

Notes: Book review in this articleBarsukov, Blinova, Vibornyky, Gulin, Pakhnov, Larionov and Kholin, Radioactive Investigations of Oil and Gas Wells, English Translation by Muhlhaus, Pergamon Press, 1965, 300 pp., 140 fig.Stuart R. Kaplan (editor), A Guide to Information Sources in Mining, Minerals and Geosciences, Vol. 2, Interscience Publishers, Division of John Wiley & Sons, New York, London, Sydney, 1965, price 95 s.F. J. Pettijohn and P. E. Potter, Atlas and Glossary of Primary Sedimentary Structures, in English, Spanish, French, German, Springer-Verlag, Berlin, Göttingen, Heidelberg, New York, 1964, 117 plates, XVI, 370 pp., cloth DM 59,–.J. Coulomb and G. Jobert, The Physical Constitution of the Earth, translated by A. E. M. Nairn, Publishers Oliver & Boyd, Edinburgh and London, price: 50 s.G. A. Gamburzew, Grundlagen seismischer Erkundung, German Edition, Leipzig, 1964, pp. 430, 271 fig., price MDN 51,–.

Notes: The common depth point method of shooting in oil exploration provides a series of seismic traces which yield information about the substrata layers at one location. After normal moveout and static corrections have been applied, the traces are combined by horizontal stacking, or linear multichannel filtering, into a single record in which the primary reflections have been enhanced relative to the multiple reflections and random noise.The criterion used in optimum horizontal stacking is to maximize the signal to noise power ratio, where signal refers to the primary reflection sequence and noise includes the multiple reflections. It is shown when this criterion is equivalent to minimizing the mean square difference between the desired signal (primary reflection sequence) and the weighted horizontally stacked traces.If the seismic traces are combined by multichannel linear filtering, the primary reflection sequence will have undergone some phase and frequency distortion on the resulting record. The signal to noise power ratio then becomes less meaningful a criterion for designing the optimum linear multichannel filter, and the mean square criterion is adopted. In general, however, since more a priori information about the seismic traces is required to design the optimum linear multichannel filter than required for the optimum set of weights of the horizontal stacking process, the former will be an improvement over the latter. It becomes evident that optimum horizontal stacking is a restricted form of linear multichannel filtering.

Notes: Downward continuation of the field in the neighborhood of a singularity of a magnetic anomaly is used to render the anomaly more two-dimensional, to make the bottom of the causal body more remote, and to obtain an auxiliary function, φ (O.z), by means of which the anomaly may be interpreted in terms of an equivalent vertical contact or step model. The concept of “apparent depth” is introduced and used in studying depth extent and susceptibility. The methods are illustrated with theoretical and practical examples.

Notes: Refraction along thin high velocity layers and along basement is investigated in two cases.a) high velocity layer just on the basement.b) high velocity layer higher above.Period and attenuation of refracted waves are givers as a function of the layer thickness H. Refracted arrivals along thin high velocity layers are visible at significant distances if the layer thickness is not smaller than A/6, where A is the longitudinal wavelength in high velocity medium. The pseudoperiod is proportional to the layer thickness H. The attenuation at large distance follows an x-ne-k1x law, where n is close to I and k1 is inversely proportional to H.Refracted arrivals along the basement are observable even in the case of thin high velocity layers situated in the overburden; their intensity is smaller and their pseudo-period larger than when no layer exists in the overburden. The intensity of the basement arrival decreases and the pseudoperiod increases with increasing layer thickness.The pseudoperiod and the attenuation of refracted arrivals along high velocity layers and along the basement are also highly dependent on acoustic contrasts.Both arrivals from a high velocity layer and from the basement can be recorded simultaneously, provided the frequency spectrum of the seismic chain is sufficiently broad. In all cases layer arrivals show a character very different from basement arrivals.

Notes: This report gives a description of Fortran II programs for filtering and spectral analysis. All programs are tested.

Notes: In the inductive method of prospecting, information on conductivity and size of conducting ore-bodies located in non-conducting host rocks, can be conveniently obtained by studying amplitude-frequency relation or amplitude-phase relation of their response with the help of suitable Master-curves. Experiments carried out in the laboratory on the scale-model method show these Master-curves to be different depending on the type of primary excitation and the shape of conductor. Cases of sphere, plate and disc in uniform field, field of line source and dipole field have been studied with an Amplitude-Phase Meter specially constructed in the laboratory for this purpose.

Notes: The occurrence of shingling in. long range refraction records often makes the task of the seismic interpreter heavier, especially when several refractors are encountered and the velocity contrasts are small.The explanation of the phenomenon given by the existing literature is examined and the theoretical results are compared with the observed data on field records.In field seismograms shingling must be separated from the effect of geological structures or lateral discontinuities.If an appropriate analysis of shingling is possible, this phenomenon can be related to the type of refracting layer, being a useful tool to a qualitative approach.On the other hand the implications of shingling are examined on the side of the geometrical interpretation

Notes: The knowledge of hydraulic and electric properties of porous media and the relations between them is essential for the quantitative evaluation of electric well logs and the solution of other reservoir engineering problems. The state of the art in this field is not yet satisfying. Theories still show considerable discrepancies with practice due to oversimplified model approaches. Empirical relations are either too coarse, not fully determined, or valid under specific geological and geographical conditions only. This article deals with the development of a general theory of the electric and hydraulic resistance behavior of porous media on the basis of a very general statistical network model. A general solution of the relations between formation factor, permeability, and porosity is presented by means of a rigorous mathematical treatment of two limiting cases of such a network. The solution shows that the product of the formation factor and the permeability can be expressed in the expectation values and the variation coefficients of pore channel cross section and shape factor and by a network factor, that depends on the mesh texture of the network. This network factor is in the range zero to one. It is further shown that the path length increase enters both the electric and the hydraulic tortuosity by its square.

Notes: A simple method of magnetotelluric interpretation is derived using the property that the earth currents flow in horizontal sheets. It is shown that when the depth is taken as two-thirds of the Cagniard's depth of penetration (Cagniard, 1953), the mean resistivity-over the depth is the same as the apparent resistivity of the medium. From a mean resistivity versus depth of penetration plot, resistivity can be easily computed at all depths of the sounding.This method gives satisfactory results in a short time and makes it possible to interpret the soundings over media of several layers. However, the results are inaccurate near maximum and minimum points of the plot as well as in the zone of thin layers.

Notes: The authors propose a method of determining the sedimentary composition of the sea-bottom by studying the variation of the frequency contents of the consecutive multiple reflections between bottom and surface of the sea.

Notes: In a previous paper by the present author a method was developed for direct interpretation of resistivity observations made with a Schlumberger electrode configuration. This method consisted of two steps. The first of these was to derive the kernel function in the integral expression for the apparent resistivity from the observed data; the second step was to derive the resistivity stratification from this kernel function.The first of these two steps depends on the electrode configuration that has been used. In the present paper the above mentioned method is modified so as to make it apply to a Wenner electrode configuration. The procedure is indicated by which the method may be adapted to any other electrode configuration in which the distances between the electrodes are finite.The second step in the interpretation, i.e. the derivation of the resistivity stratification from the kernel function, is independent of the electrode configuration used, and therefore needs no further discussion in the present context.

Notes: A method designed to study the defoliation of individual tillers in a set-stocked sward is described. This was used on S23 ryegrass swards carrying 19 (medium-stocked) and 30 (heavily-stocked) sheep/ac.The tillers in the heavily-stocked sward were defoliated, on average, every 7–8 days, and those in the medium-stocked sward every 11–14 days. The total green leaf length (GLL) of tillers grazed by the sheep was generally greater than that of tillers not grazed. On average 27 and 40% of the GLL of tillers in the medium- and heavily-stocked swards respectively was removed at each grazing. Older leaves on the grazed tillers were defoliated much less frequently than were younger leaves.It is suggested that a rational analysis of the relationship between the grazing animal and the grazed sward cannot be made without more work of this nature.

Notes: A study of a sward sown to Lolium perenne and Trifolium repens was made so that the inter-relationship of the plant and animal communities might be more fully understood within the context of a sheep husbandry experiment. At the higher of 2 stocking rates intensive grazing induced the grass species to assume a prostrate growth habit in the first year: at the lower rate of stocking this condition was less prevalent. The only species to invade the sward and make progress over the 5 years were Poa annua, P. trivialis. and Agrostis stolonifera. Some control of A. stohnifera was gained when grazed swards were cut for silage. The Poa species eventually made up about 50% of the ground cover of all swards.

Notes: The effect of 4 or 5 forms of nitrogenous fertilizer on the yield and botanical composition of a perennial ryegrass/white clover sward was examined in 3 different years. The uptake of N by the grass was also estimated. Ammonium nitrate (as Nitro-Chalk), ammonium sulphate and urea gave similar yield increases, although in one year, when high rainfall followed the application of fertilizer, urea was slightly inferior. Gas liquor gave variable responses in the 3 years. Nitroform, a urea-formaldehyde, was generally less effective than the other forms of fertilizer. The uptake of N from Nitro-Chalk, sulphate of ammonia and urea did not vary greatly from year to year although the uptake of soil N by the untreated control did.Response to N in the yield of dry-matter varied from year to year. This variation was due partly to differences in the amount of clover present and partly to differences in the extent to which N taken up by the grass was used for the synthesis of dry-matter.The white clover content of the sward was not greatly reduced in spring by the application of the fertilizer, and there were no consistent differences between the effects on clover of the forms of the fertilizer. A reduction was apparent in the summer but not in the autumn.It may be necessary to increase replication above the level of 3 to 6 which is frequently employed in field experiments if more precise quantitative estimates of response and of the relative efficiency of various forms of nitrogenous fertilizer are required.

Notes: Book reviewed in this article:CLAYTON, W. D. An introduction to Arber's The GramineaeKLAPP, E. Taschenbuch der Graser. [Handbook of grasses.]KOBLET, R. Der landwirtschaftliche Pflanzenbau, unter besonderer Berucksichtigung der schwei-zerischen Verhaltnisse.

Notes: Three comparisons were made, with non-lactating fistulated cows, of the voluntary intake of silage and hay prepared from similar herbage. On average 28% more dry matter was eaten as hay than as silage. Silage and hay had similar digestibilities, but silage residues tended to remain in the gut longer than those of hay. The amount of digesta in the reticulo-rumen immediately after a meal ad lib. was greater with hay than with silage. The cows spent longer eating and ruminating per kg dry matter of silage than of hay. The results are discussed in relation to possible factors determining the voluntary intake of silage.

Notes: A field trial was carried out in which 3 groups of cattle were grazed on a paddock system with and without supplementary barley. The cattle were 6 months old when turned out to grass and were each fed 4 lb/day of barley for one week to prevent any adverse effect from an abrupt change of diet. The trial began on 14 May and continued until 8 October. The mean liveweight gain obtained on the unsupplemented grass was only 0·97 lb/day up to 20 August and owing to the poor growth of the animals a supplement of 4 lb barley/head/day was then introduced. The daily liveweight gain for the remainder of the trial was 1·94 lb. When a supplement of 4 lb barley was provided throughout the trial the mean daily liveweight gain was 1·61 lb. When barley was fed ad lib. intake averaged 12·3 lb/head/day throughout the trial and the mean daily gain was 2·45 lb.Indoor digestibility and nitrogen retention trials were carried out. The starch equivalents of diets on the three treatments were 63·7, 68·3 and 69·5, respectively. The respective mean daily intakes of dry matter were 11·2, 11·9 and 11·8 lb, and the mean daily retentions of N were 35·0, 35·8 and 33·6g. These results indicate that although the grass was of good nutritive value the poor performance of the animals on grass alone was mainly due to their inability to graze sufficient grass.

Notes: An account is given of the production and use of grass in Lancashire, including statistical information relating to acreages and livestock numbers in June, 1963; a map shows the distribution of grassland in the county as percentages of the agricultural area. For convenience the county is divided into 5 areas, each with different farming systems. Reference is made to the Ministry of Agriculture's Experimental Husbandry Farm and its influence on farming in the surrounding districts in East Lancashire.

Notes: The grazing of 3 relatively productive grasslands (Festucaf Agrostis) by hill sheep was examined in relation to herbage consumption, grazing pressure, dung deposition and the number of sheep in the area. Herbage intake ranged from 400 Ib/ac/annum (dry weight) on the highest (2450 ft O. D.) and most exposed grassland to 800 Ib/ac/annum on a grassland (1700 ft O. D.) adjacent to extensive heather moorland on blanket bog. The highest pressure (5·5 sheep/ac) was also found on grassland surrounded by blanket bog (1 sheep/14 ac).

Notes: The in vitro digestibility of organic matter and cellulose was determined in 17 fodders collected in western New South Wales. Further determinations were made on samples fortified or not by the addition of glucose, urea and yeast extract. There was a significant positive response to fortification in both organic-matter and cellulose digestibility, the magnitude of the response varying with the fodder sample tested. The relationship between organic-matter digestibility and cellulose digestibility was close only in the case of grasses, but for all samples consideration of both the amount and digestibility of cellulose accounted for 97% of the variation in organic-matter digestibility. The results suggest that an inhibitor preventing cellulose digestion was present in Cassia eremophila.

Notes: A two-dimensional, passive element electric analog model was used to determine the spatial distribution of natural ground-water recharge in the Santa Cruz River basin of southern Arizona. Existing records were used to draw a ground-water level contour map of the area in its undeveloped condition. The model was made to duplicate these contours by varying inputs from known locations of recharge. Recharge distribution as determined by the model was consistent with previous estimates, but no direct correlation was found with the contributing drainage area.

Notes: The tidal efficiencies of wells tapping the principal artesian aquifer in Glynn County, Georgia decrease with distance from the influencing tidal body and also decrease with well depth. Although the magnitude of water-level fluctuation of these wells is largely dependent upon the distance to a large tidal body, the time of a high or a low water level in the wells is mainly dependent upon the time of a high or a low tide in a small, nearby tidal body. A modified formula for computing tidal efficiency is developed:〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT24:GWAT_24_mu1"/〉 From this formula, tidal efficiency can be calculated rapidly and easily

Notes: The frequency distribution of dissolved-solids content of ground waters in geologically and climatologically homogeneous terrane units commonly approximates a log-normal distribution. A graphic logarithmic transformation is de-scribed which permits rapid calculation of approximate values for the mean, standard deviation, and coefficient of variation. Statistical parameters calculated by this method show good agreement with known physical conditions in the terranes studied and are precise enough for use as a mea-sure of variability of quality of ground waters for national planning purposes.

Notes: Photogeologic study has been useful in the location of ground-water sources in the state of Sao Paulo, Brazil, and could be important to the investigation of water resources in other areas.Until 1963, it was believed that large areas of the state were unsuited for the location of ground-water wells (as in pre-Devonian crystalline formations) and others weregenerally considered too hazardous (Paleozoic and Tertiary: sandstone lenses in shales). Since that time, when aerial photographs of the whole state became available, the authorhas verified an earlier hypothesis of his own that there are actually very few areas in the state which do not have suitable locations for water wells, and that photogeology is a most valuable method of prospecting.The water sources are parts of highly developed fault/ fracture systems which are identifiable on aerial photo-graphs, at least in this warm humid climate with dry season. Over the fractures the rocks are deeply decomposed, the debris are removed in the rainy season, and existence of water in the dry season promotes higher and denser vegeta-tion along aquiferous fractures, which usually are located in deep straight-line valleys. Even where competent beds are overlain by more than 100 m of unconsolidated strata, many discontinuous nets of parallel straight-line segments are detectable probably because all fractures are really faults with significant throw.To be most effective, the method requires stereoscopic study of areas having dimensions on the order of 10 × 10 km. The selection of locations for drilling should be sup-ported by analyses of the dip of fracture planes (hade) and by other geological-geophysical methods, especially by subsoil electrical resistivity surveying.

Notes: The purpose of this paper is to stimulate additional interest in the hydrogeologic aspects of the International Hydrological Decade (IHD) program and to urge the full cooperation and participation of hydrogeologists in the research and educational activities of the Decade. The IHD, 1965–74, will strengthen the scientific base for water use and conservation, stimulate education and training in hydrology, and improve the ability of developing and developed countries alike to cope with their water resources problems. UNESCO provides an international intergovernmental umbrella and the Secretariat for IHD. More than 90 Member States of UNESCO are participating in IHD and a majority of these have established National Committees for IHD.The UNESCO/IHD program will consist primarily of activities of participating countries themselves, catalyzed, coordinated, and supplemented by international intergovern-mental agencies and scientific associations. Activities of Member States of UNESCO include: collection of basic data through data analysis and applied hydrology; applied and basic research; continental and global water balances and the global hydrological cycle; establishment of hydrological networks and the development of technical competence; fundamental research; definition of principal hydrological features of countries such as precipitation, discharge of water, sediment and dissolved load, evapotranspiration, distribution of tritium in precipitation, surface and ground waters; experimental basin studies to provide insight on the interplay of environmental and hydrological parameters in a broad range of geological, climatic, and ecological conditions; distribution of water in the atmosphere, in lakes and rivers, underground, in permanent ice and snow and permafrost; studies of the rate at which water moves through the hydrologic cycle; use of orbiting satellites and remote sensing instruments for measuring phenomena in the atmosphere and at the Earth's surface and for relaying observational data; organization of egional advanced training and study courses and hydrological institutes; exchange of teams of experts, exchange of professors and research scientists; and organization of symposia and regional seminars.The US/IHD program focuses on the following five major objectives: (1) large-scale balances of water and water-borne material studies; (2) hydrological performance of river, lake, and ground-water basin systems studies; (3) studies of specific hydrological processes and their variations in time, and improvement of methods and techniques; (4) education and training; and (5) services providing coordination and administration support. These objectives provide a framework within which the scientific and engineering community can contribute to IHD. A provisional US/IHD program statement identified, among others, the following hydrogeologic activities: estimation of ground-water discharge to the sea, effects of variations in piezometric head on land subsidence, hydrology in limestone areas, radionuclide tracer studies, chemical behavior of ground water, and dispersion in moving ground water.Hydrogeologists are urged to submit proposals concerning activities for possible inclusion in the US/IHD program. The following seven criteria guide the formulation and inclusion of activities in the US/IHD program by the U. S. National Committee for IHD: (1) the activity is sufficiently fundamental or aimed at results so useful that it will interest all hydrologists; (2) the activity requires joint or coordinated work in two or more countries; (3) the activity concerns a problem whose solution and verification would be improved by work in two or more countries; (4) the activity concerns continental, hemispheric, or global phenomena or processes; (5) the activity requires action in international areas such as polar regions, international waters, and multi-national basins; (6) the activity involves the hydrologic use of earth-orbiting satellites; and (7) the activity involves intercountry exchange or visits of personnel (in some instances, the exchange or visit itself may be the main item of interest). Proposals may be of projects already in progress, for expansion or modification of on-going projects, or for new work. Proposals may be submitted as contributions, requiring no financial aid from or through the IHD; for endorsement by IHD as an aid in obtaining financial aid elsewhere; or, when funds become available, as IHD projects receiving financial assistance from the IHD. Further information may be obtained from: U. S. Na-tional Committee for the International Hydrological Decade, National Academy of Sciences, 2101 Constitution Avenue, N. W., Washington, D. C. 20418.

Notes: A type-curve method for determining anisotropy of unconfined aquifers, developed from electric analog simulation, is applied to drawdowns observed near, a well pumping from a glacial outwash aquifer at Piketon, Ohio. The coefficient of vertical permeability, P z'averaged 365 gpd per square foot. Computed drawdown for the pumped well, based on this value, differed by only a small amount from the observed drawdown. The coefficient of storage, determined from type curves for an image well system, averaged 0.20, typical of unconfined aquifers. Application of the method required a thorough knowledge of geohydrologic controls operating at the test site.

Notes: Criteria and factors are considered which affect the design of a Hele-Shaw viscous flow model for use in ground- water studies. Procedures and construction techniques for assembling such a model are outlined. Some of the advantages and drawbacks in using a viscous flow model are discussed, Three examples are used to demonstrate the use of the model

Notes: A nuclear (atomic) explosive, detonated at suitable depth below the land surface, appears to offer substantial advantages and economies as a tool in the development and management of water, under certain special hydrologic situations. It is appropriate, therefore, that we seek to understand not only the potentials, but also the limitations of such a detonation. This paper is a first, small step toward that end.Greatly over-simplified, what does an underground nuclear detonation do that it can become a tool of water development and management? Consider first a detonation at a depth sufficiently great that none of the products vent to the atmosphere. Minimum depth for such “containment,” in feet, is close to: 〈displayedItem type="mathematics" xml:id="m1"〉1〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT13:GWAT_13_m1"/〉in which W = explosive energy, in kilotons.