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In a paper published by one of us in this Journal [Price, 1963], an apparent longitudinal variation was found in the worldwide pattern of the noncyclic changes averaged over the 60 quiet days of 1958. The changes appeared to have a maximum between 120°E and 180°E and to decrease progressively on going westward around the earth until a minimum was reached between 120°W and 180°W. This is illustrated in Figures 1 and 2 of Price's paper. Some further studies of the noncyclic variation, derived in the course of our investigation of the Sq field [Price and Stone, 1964], have lead us to believe that the apparent departure from axial symmetry exhibited by the above-mentioned figures is not a real feature of the actual N field at a given instant of universal time, but arises from the fact that the noncyclic changes shown in these figures relate to different epochs of the Greenwich day. For stations east of Greenwich up to 18O°E, N has been estimated for a 24-hour period that includes a part of the day preceding the international quiet day, and for stations west of Greenwich a part of the following day. To estimate the possible effect of this procedure, N(H) averaged for the 60 quiet days has been estimated at several stations for a sequence of successive 24-hour periods covering and overlapping the Greenwich day. In all cases a progressive decrease of N(H) is found, the decrease being fairly steady for periods beginning and ending during the night hours, but showing appreciable variability for the successive periods ending during daylight hours. This is well illustrated by the results for Apia (11.45 hours west of Greenwich) shown in Figure 1. There is a progressive decrease from 10 to 5 γ throughout the 25 successive periods ending at each hour local time. Had this station been nearly 12 hours east, instead of nearly 12 hours west of Greenwich, the estimated N(H) would have been 10 instead of 5 γ. This accords well with the apparent rapid change of N(H) for stations near 180° shown in Price's paper.

Dyed textiles are, in general, less resistant to colour change when weathered than when exposed behind glass to daylight. No standard method exists for the assessment of weathering fastness. An outdoor weathering test and a wet fading lamp test are described, and their merits and deficiencies discussed. The method of assessment allows direct comparison between the weathering (or wet-fading-lamp) fastness of a pattern and the light fastness according to B.S. 1006. These methods have yielded useful results in practice, and this paper records some work carried out to date.

PERIODICALLY, cultures of coliform organisms in simple synthetic medium (glucose–phosphate–ammonium salt) have failed to grow when aerated in this laboratory, contrary to experience in other towns. This culminated in a few weeks when such cultures refused to grow at all, so that the possible presence of poisons in the air was suspected. Consequently the air intake of the compressor was placed outside the laboratory buildings. The phenomenon persisted during the daylight hours but was eliminated at night time.

Although the method of measuring the varying intensity of the chemically active rays, as affecting chloride-of-silver paper of constant sensitiveness described in the Bakerian Lecture for 1865, has been the means of pointing out many important facts concerning the distribution of the sun’s chemical activity through the atmosphere as well as in different situations on the earth’s surface, it has not as yet been introduced as a regular portion of the work of meteorological observatories. Until this is done, and the measurements are regularly continued and made in many situations, we cannot hope to obtain any thing like a knowledge of the laws of distribution of these rays over the earth’s surface, or any information as to the yearly variation of the solar chemical activity. This non-adoption of the method has to be explained, not in any want of reliance in the process or in the results, but in the fact that, in order to obtain a satisfactory curve of daily chemical intensity, at least hourly observations need to be made; this involves, however, the expenditure of so much time and labour that the permanent observatories, already too heavily weighted, have found it impossible to undertake the necessary work. In the present communication I have to describe a modification of the above-mentioned method, which, whilst preserving untouched the principles upon which it is based and the amount of exactitude of which it is susceptible, reduces the personal attention needed for carrying out the measurements to a minimum, and thus renders its adoption in observatories possible. According to this plan, the constant sensitive paper is exposed to the action of total daylight at given intervals, say at every hour, during the day, by a self-acting arrangement, for accurately known times. The insolation-apparatus, stocked with sensitive paper, is placed in position either early in the morning of the day during which the measurements have to be made, or on the previous night; and by means of electric communication with a properly arranged clock, the sensitive paper is exposed every hour during the day, so that, in the evening, the observer has only to read off in the ordinary manner the hourly intensities which have been recorded on the paper during the day.

In an earlier paper in ‘Building Science’ [1] attention was drawn to the advantages of deep office spaces and how these may be satisfactorily attained. It was pointed out, though, that deep blocks will probably, because of the requirements of a view from the building and the view of daylight, require most office spaces to be large and open planned. This paper is concerned with describing some of the psycho-social consequences of opting for large or small areas.

In this paper an account is given of investigations of shortwave transmission effects made during the past two years. These include, firstly an investigation of scattering, multiple signals and signal mutilation, which supplies perhaps the main bulk of the paper, secondly the results of a nine months' direction-finding interception of short-wave commercial stations, and finally a discussion, in the light of these results, of the problems of short-wave transmission and such cognate subjects as the nature and constitution of the Heaviside layer, fading and polarization effects.An opportunity is afforded for the revision of conclusions arrived at in the author's previous paper.* The chief alteration is in the estimated height of the lowest levels of the Heaviside layer in daytime. The accumulation of evidence from the time-lag experiments of Breit and Tuve, and the interference experiments of Appleton and those of Hollingworth (which incidentally both give the group time and consequently an over-estimate of the height) have led the author to a revision of the mathematical result by which he obtained from long-wave measurement the effective height of the daylight ionized layer, and in doing so he has found an error which makes the estimated height just double that previously obtained, for inseatd of the relationd0 = h2/λ† we have d0 = h2/λ, making the estimated height lie between 80 km for summer and 97 to 100 km for winter.Previously the value of τ, the mean time between collisions, was found to lie between the limits 0.5 × 10−6 and 0.5 × 10−7 (on the basis of magnetic storm effects). Calculations based on the kinetic theory would imply a height of between 76 and 92 km for these values of τ in fairly close agreement with the above, and there is no necessity to make the rather forced assumption previously made that the electronic mean free path was some 10 to 50 times greater than that calculated from the normal kinetic theory on the assumption that the electron may penetrate the outer rings of the molecules without being appreciably deflected. Apparently this effect occurs only in inert gases, such as helium, and is not likely to occur in the upper atmosphere.With regard to scattering, the glancing angle for transmission, great-circle bearings of the main rays, and the daylight attenuation, the author has found the previous conclusions to be on the whole well-founded.Some modification of the lower wave-length limit for night transmission is required, and the author finds that this lower limit depends on the time of the night and season. Late-night regions behave very differently from early-night regions, thus confirming Appleton's results showing a progressive change in the Heaviside layer during the hours of darkness. The short-wave daylight limit appears to be close to 10m, but sporadic long-distance transmissions have been observed on wave-lengths shorter than this.The interpretation of many observations of short-wave transmission depends upon a previous experimental knowledge of scattering. A discussion of scattering will therefore be given first, and later the general results of long-distance and short-distance direction -finding will be considered. Fading and magnetic storms will next be discussed, then “skip effects”, and finally a general theoretical discussion in the light of the results obtained will be given.

In the last memoir on Photochemical Measurements, presented to the Royal Society, Professor Bunsen and I described a method for determining, by simple observations, the varying amount of chemical action effected by the direct and diffuse sunlight on photographic paper, founded upon a law discovered by us, viz. that equal products of the intensity of the light into the times of insolation correspond within very wide limits to equal shades of tints produced on chloride-of-silver paper of uniform sensitiveness—so that light of the intensity 50, acting for the time 1, produces the same blackening effect as light of the intensity 1 acting for the time 50. For the purpose of exposing this paper to light for a known but very short length of time, a pendulum photometer was constructed; and by means of this instrument a strip of paper is so exposed that the different times of insolation for all points along the length of the strip can be calculated to within small fractions of a second, when the duration and amplitude of vibration of the pendulum are known. The strip of sensitive paper insolated during the oscillation of the pendulum exhibits throughout its length a regularly diminishing shade from dark to white; and by reference to a Table, the time needed to produce any one of these shades can be ascertained. The unit of photo-chemical intensity is assumed to be that of the light which produces upon the standard paper in the unit of time (one second) a given but arbitrary degree of shade termed the normal tint. The reciprocals of the times during which the points on the strip have to be exposed in order to attain the normal tint, give the intensities of the acting light expressed in terms of the above unit. According to this method the chemical action of the total daylight ( i. e . the direct sunlight and the reflected light from the whole heavens) has been determined, by means of observations made at frequent intervals throughout the day, and curves representing the variation of daily chemical intensity at Manchester have been drawn. The labour of obtaining a regular series of such daily measurements of the chemical action of daylight according to this method is, however, very considerable; the apparatus required is bulky, the observations can only be made in calm weather, and the quantity of sensitive paper needed for a day’s observations is large.

The aim of the present communication is to describe a simple mode of measuring the chemical action of total daylight, adapted to the purpose of regular meteorological registration. This method is founded upon that described by Prof. Bunsen and the author in their last Memoir on Photochemical Measurements, depending upon the law that equal products of the intensity of the acting light into the times of insolation correspond within very wide limits to equal shades of tints produced upon chloride-of-silver paper of uniform sensitiveness—light of the intensity 50, acting for the time 1, thus producing the same blackening effect as light of the intensity 1 acting for the time 50. For the purpose of exposing this paper to light for a known but very short length of time, a pendulum photometer was constructed; and by means of this instrument a strip of paper is so exposed that the different times of insolation for all points along the length of the strip can be calculated to within small fractions of a second, when the duration and amplitude of vibration of the pendulum are known. The strip of sensitive paper insolated daring the oscillation of the pendulum exhibits throughout its length a regularly diminishing shade from dark to white; and by reference to a Table, the time needed to produce any one of these shades can be ascertained. The unit of photo-chemical action is assumed to be that intensity of light which produces in the unit of time (one second) a given but arbitrary degree of shade termed the standard tint. The reciprocals of the times during which the points on the strip have to be exposed in order to attain the standard tint, give the intensities of the acting light expressed in terms of the above unit. By means of this method a regular series of daily observations can be kept up without difficulty; the whole apparatus needed can be packed up into small space; the observations can be carried on without regard to wind or weather; and no less than forty-five separate determinations can be made upon 36 square centimetres of sensitive paper. Strips of the standard chloride-of-silver paper tinted in the pendulum photometer remain as the basis of the new mode of measurement. Two strips of this paper are exposed as usual in the pendulum photometer: one of these strips is fixed in hyposulphite-of-sodium solution, washed, dried, and pasted upon a board, furnished with a millimetre-scale. This fixed strip is now graduated in terms of the unfixed pendulum strip by reading off, by the light of a soda-flame, the position of those points on each strip which possess equal degrees of tint, the position of the standard tint upon the unfixed strip being ascertained for the purpose of the graduation. Upon this comparison with the unfixed pendulum strip depends the subsequent use of the fixed strip. A detailed description of the methods of preparing and graduating the strips, and of the apparatus for exposure and reading, is next given. The following conditions must be fulfilled in order that the method may be adopted as a trustworthy mode of measuring the chemical action of light:— 1st. The tint of the standard strips fixed in hyposulphite must remain perfectly unalterable during a considerable length of time. 2nd. The tints upon these fixed strips must shade regularly into each other, so as to render possible an accurate comparison with, and graduation in terms of, the unfixed pendulum strips. 3rd. Simultaneous measurements made with different strips thus graduated must show close agreement amongst themselves, and they must give the same results as determinations made by means of the pendulum photometer, according to the method described in the last memoir.

The propagation of long and short waves over long distances has been extensively studied, and the underlying principles are, to a large extent, understood. The question of the propagation of medium waves by direct ray, which forms the subject of the following paper, has not previously received so much attention. The paper is written with a view of enabling predictions to be made as to the field strength of direct-ray transmission on wavelengths between 60 meters and 2000 meters. The main part of the paper is concerned with daylight transmission. The question of night transmission and the influence of the Heaviside layer is considered briefly at the end.

For colorimetry of daylight fluorescent materials, a daylight illuminant of higher ultra-violet energy content than that of source C is needed. In an earlier paper it was shown that an increase in ultra-violet energy can be obtained by supplementing source C with another source containing a tungsten lamp and an ultra-violet transmitting filter. Newer data indicate that the ultra-violet content of average daylight may be considerably higher than that assumed in the previous paper. The purpose of this investigation is to see what kind of approximation to this type of ultra-violet energy distribution is possible, using the same arrangement as before. It is shown that an approximation, satisfactory for all cases of daylight fluorescent colorimetry can probably not be obtained with only one supplementary source, using conventional filters and reasonable (tungsten) lamp intensities. A satisfactory solution for the type of ultra-violet distribution involved seems to require at least two supplementary sources. Ex...

This paper discusses the theory that normal long-distance short-wave communication is broaght about by a series of refractions and reflections. It shows how, if we know the "range/best wavelength" characteristic for ranges which entail only one "hop" of the rays, we can predict the best wavelength for any larger range necessitating a number of hops, it being assumed that propagation conditions, such as ionic distribution, remain the same throughout all those ranges. Single-hop characteristics given by the author in a previous paper are ased in this way to derive the characteristic for longer ranges in daylight. The result is in close accord with a curve given by Lloyd Espenschied which shows the result of actual experiment over long ranges. For conditions of darkness the present theory cannot be fully tested owing to incompleteness of the data over short ranges, but general agreement is indicated. It is shown that the theory helps to account for the phenomenon of "fading," and for dissimilarities in reception at stations situated a few miles apart, but both receiving from the same sending station. Suggestions are made as to future research. It is thought that multiple refraction and reflection is the most satisfactory explanation of the effects met with in the course of ordinary short-wave communication at long ranges.

This paper attempts to add a further factor to the work on layout planning described in previous papers in this journal [1–4]. Some spaces need to be provided with daylight and to be located accordingly; the merits of various methods of handling this requirement are discussed.

This paper presents a critical resume of the performance of apparatus employed for radio direction determination either by transmission or by reception. After an historical summary of results obtained in various parts of the world, a brief description is given of the fundamental principles underlying radio direction-finding. In this section attention is drawn to the application of the principle of reversibility to this art, by the aid of which the behavior of directive radio transmitters can be largely predicted from the more numerous results and greater experience already obtained with directional receivers. The next two sections of the paper give a review of the results obtained in Great Britain during the course of extensive investigations into this subject during the past seven years. Observations obtained from thirteen direction-finding receiving stations, specially erected for the purpose, have been carefully analysed and the performance of the apparatus studied under a variety of conditions, including operation in daylight and darkness, and both oversea and overland. In addition, some two years have been spent in studying the performance of a rotating-loop beacon transmitter, by means of which accurate radio bearing can be obtained with any type of receiving apparatus. The later portions of the paper deal with the application of direction-finding to marine navigation, and of the possible effect of coastal and night errors in connection therewith.

The method of determining the chemical intensity of daylight described by one of us presents a convenient means of experimentally comparing the intensity of the chemically active rays which reach the earth’s horizontal surface directly from the sun with that of the same rays reflected from the atmosphere and constituting diffuse daylight. For this purpose it is only necessary alternately to expose pieces of the standard sensitive paper, according to the method described in the memoir above mentioned, to the action of the total light of day, and to the diffuse daylight alone, which is easily done by cutting off the sun’s direct rays from the sensitive paper, by throwing upon the paper a shadow cast by a small screen, having an apparent diameter slightly greater than that of the solar disk. In the first case the chemical intensity of the total daylight, in the second that of the diffuse light is determined; the difference between these two observations giving the chemical intensity of the direct sunlight. As the experiments which we have already made in this direction have led us to conclusions differing altogether from those derived from theoretical considerations concerning the relative chemical intensities of direct and diffuse sunlight, we think that, although this investigation is incomplete, the results are worthy of the attention of the Society. No direct photometrical determinations of the relative intensity of sun and diffuse light have up to this time been made; but Clausius has calculated this relation for varying altitudes of the sun, founding his calculations upon the hypothesis (generally adopted by meteorologists to explain the red tints of the morning and evening sky) that the diffused light is reflected, not from the particles of air or solid floating material, but from the minute vesicles of water which are supposed to be always contained in large quantities in the atmosphere. According to this hypothesis, Clausius obtained the following numbers as expressing the intensities of direct sunlight and diffused daylight for altitudes varying from 20° to 60°:— The measurement of the relative chemical intensities were made at three localities: (1) Owens College, Manchester, 53° 29' N., and 0 h 9 m 0 s W.; (2) the Observatory, Cheetham Hill, near Manchester; and (3) the summit of the Königstuhl, near Heidelberg, 1900 feet above the sea, in 49° 24' N., and 34 m 48" E. We are indebted for the latter observations to Dr. Wolkoff, who kindly forwarded us his results through Professor Bunsen.

The paper describes further examination of the daylight long wave signal measurements of the Bureau of Standards for evidence of correlation with solar activity. It has already been shown that a probable correlation exists between signals and sunspots when the observations are continued for several years and are averaged in periods of a month or more. The present paper deals especially with observations averaged in shorter (5-day) periods. Here while the relationship is generally evident it is sometimes obscured by an apparent relative phase shift between the signal and sunspot curves.

The difficulty of securing in England a sufficient number of consecutive cloudless days to render it possible to determine with any degree of accuracy the relation existing between the sun’s altitude and the chemical intensity of total daylight, induced us to undertake a series of measurements on the west coast of Portugal, where during the months of July and August the sky is generally cloudless. The method of measurement employed was that described by one of us in previous communications to the Royal Society, founded upon an exact estimation of the tint which standard sensitive paper assumes when exposed for a given time to the action of daylight. The observations, the results of which are given in the following communication, were made in the autumn of 1867, through the kindness of Thomas Creswell, Esq., at the Quinta do Estero Furado, situated on the flat table-land on the southern side of the Tagus, about 8½ miles to the south-east of Lisbon, lat. 38° 40' N. and long. 9° W. The sensitive paper was exposed in the plane of the horizon, the instrument being placed upon a carefully levelled stand at the height of 4 feet 5 inches above the level of the ground in a sandy field having a clear horizon, the most considerable object in the neighbourhood being a house distant 130 paces to the west, the roof of which subtended an angle of 7° with the plane of the paper.

A technique for measuring the dynamic behaviour of concrete piles during driving operations using a He-Cd laser is reported. Traces of pile movement are recorded on photo-sensitive oscillograph paper which is attached to the pile and exposed to a laser beam transmitted from a fixed point. The oscillograph paper is filtered against the background daylight but is sensitive to the wavelength of the laser at around 441.6 nm. Using this technique clear traces of the rebounding of concrete piles have been obtained in daylight.

In this communication the authors give the lesults of a seiies of determinations of the chemical intensity of total daylight mate in the autumn of 1867 on the flat tableland on the southern side of the Tagus, about 8½ miles to the south-east of Lisbon, under a cloudless sky, with the object of ascertaining the relation existing between the solar altitude and the chemical intensity. The method of measurement adopted was that described in a previous communication to the Society, founded upon the exact estimation of the tint which standard sensitive paper assumes when exposed for a given time to the action of daylight. The experiments were made as follows:— 1. The chemical action of total daylight was observed in the ordinary manner. 2. The chemical action of the diffused daylight was then observed by throwing on to the exposed paper the shadow of a small blackened brass ball, placed at such a distance that its apparent diameter, seen from the position of the paper, was slightly larger than that of the sun’s disk. 3. Observation No. 1 was repeated. 4. Observation No. 2 was repeated.

Publisher Summary This chapter discusses the relationship of the position of the drawing board to the lighting available. To enable the student to make a good drawing, it is essential that the drawing board should be situated in such a position that the light, daylight or artificial light, for a right-handed person should fall on the right-hand side of the set-square, and for a left-handed person on the left. The student should be seated comfortably to work more efficiently if the top of the drawing board is raised approximately 3 inches. Working drawings can be made in pencil on handmade paper, cartridge paper, or detail paper. Handmade paper has a clean and hard drawing surface but has rough, untrimmed edges. It can be used for pencil or ink drawings; but, owing to the fact that it is expensive, it is reserved for more important design work. When lettering or hand printing is used, it can be either vertical or sloping; however, both types should not be used on the same drawing.

Rats when 28 days old, at which time they were weaned, were placed in groups of five in the dark room, in the stock room, and given daily exposures of about two hours to direct sunlight and to diffuse daylight on the roof as described in the preceding paper. Counts were made of the blood cells at the ages given in the tables under the four conditions indicated. The red counts were made from the first drop of blood exuding after the tip of the tail was severed. Both a direct and an indirect method were used for counting platelets. Details will be given in a later paper. The same pipettes were used throughout for all counts.Aside from reestablishing the “normal” count at these ages, the stimulating influence of direct sunlight and diffuse daylight, perhaps of fresh air, and the inhibitory influence of darkness on the reds and platelets is obvious from the table. The figures given for the reds represent the averages of counts on five rats, i. e., 30 rats under each of the four environmental conditions, at th...

Information on the exact time of the daily resting and feeding periods of incubating ring-necked pheasant (Phasianus colchicus) hens and the daily time of egg laying is rather meager. Leopold (1933) gave dawn and 4:00 p.m. as the times at which incubating pheasant hens leave the nest. Baskett (1947) found no definite time at which he could predict with accuracy that any individual hen would be away from the nest. He states that eggs were generally laid in the interval from about two hours after sunrise to two hours before sunset, or between the two daily feeding periods. Difficulty in obtaining accurate data is largely responsible for this lack of information. Direct observation of the nest can be carried on only during daylight hours and may cause desertion of the nest or abnormal behavior by the hen. The need for a method of automatically recording the daily movements of nesting pheasant hens was evident. A number of methods have been devised for recording nesting activities of song birds. Baldwin and Kendeigh (1927) described the use of a thermocouple and recording potentiometer to record nesting activities. The application of heat to the eggs registered the presence of the bird, and a drop in temperature depicted its departure. The thermograph could be placed in the nest with little difficulty, but the recording potentiometer required an electric current, a limiting factor in its use. Kendeigh and Baldwin (1930) detailed the use of an itograph, an electromagnetic device particularly adapted for use at nests with but one approach. Another electromagnetic instrument, the terragraph, was invented by a German, Count von Hegendorf, for studying the habits of foxes and badgers, and was applied to bird activities by Bussman (1933). The apparatus consisted of a paper dial-plate marked at half-hour intervals on a revolving disk, with a carbon paper on top. A pencil attached to a telegraph magnet pressed on the carbon paper when the circuit was made, making a short line on the paper dialplate below. Two small pieces of wood fastened at one end by a flat steel spring comprised the nest contact. The contact was placed in circuit by means of an insulated copper wire with two pocket batteries and the telegraph magnet. Kuusisto (1941) used a glass tube containing mercury and with one end expanded like a thermometer as a thermo-contact.

IN the discussion which followed the papers by Dr. J. R. Baker and Mr. R. M. Ranson and Prof. T. H. Bissonette, read before the Royal Society on Feb. 4, I suggested that their conclusions concerning light as a factor in sexual periodicity involved a principle of wide application. Dr. Baker had referred in his paper to the practical application of this principle by the poultry industry, and I remarked that Mr. Hammond had pointed out to me that it was possible to construct graphs for the principal countries of the world showing a well-marked correlation throughout the year between egg production and the incidence of daylight. I stated further that the effects of artificial illumination were known also to breeders of canaries and other cage-birds, and that within my own experience the collared turtle-dove which has been kept under conditions of domestication for many generations will breed freely under ordinary room conditions in mid-winter under the added stimulus of artificial light in the evenings. I might have added that in tropical countries where environmental conditions are similar throughout the year, such as the Cameroons, the native birds have no restricted breeding season but breed at any time. Moreover, in the case of the Brent goose and various other species of geese, although pinioned birds may be kept for years in a state of perfect health in semi-captivity, they never or very rarely breed, and I suggested that such birds require the stimulus of prolonged daylight, which they obtain in their normal breeding habitat within the arctic circle, in order to excite the activity of the reproductive organs.

Since the proposed index to rate the color rendering properties of light sources, there has been a desire on the part of many individuals, especially those concerned with marketing lamps, to put this on an absolute basis. This would allow all lamps to be rated on the same base line thus allowing, for example, the direct comparison of the color rendering properties of a warm white and a daylight lamp. In this paper a method of doing this is presented, followed by the reasons why this serves no useful purpose.

In the year 1864 I communicated to the Royal Society the description of a method for the Meteorological Registration of the Chemical Intensity of Total Daylight, founded upon an exact measurement of the tint which standard sensitive paper assumes when exposed for a given time to the action of daylight. During the last two years measurements of the chemical intensity, according to this plan, have, through the kindness of Dr. Balfour Stewart, been made regularly every day at the Kew Observatory by Mr. T. W. Baker, and thus the practicability of carrying at a continued series of observations according to this method has been effectually and satisfactorily tested.

Bissonnette's (1932) remarkable discovery that additional illumination would induce œstrus in anœstrous ferrets has naturally led to much speculation as to what controls the onset of the breeding season in the normal ferret. An obvious interpretation of Bissonnette's results, and one apparently favoured by Marshall (1932), suggested that the beginning of the breeding season of the normal female in March-April is influenced by the increasing duration of daylight. Such a hypothesis, however, could not be extended to many mammals. Those breeding in the autumn (sheep, for instance) would require a radical alteration of the hypothesis, while nocturnal and subterranean mammals can hardly be affected directly by the duration of daylight. Even in the ferret the hypothesis scarcely seemed valid, because the initial breeding season changes are evident histologically in December and January (Allanson, 1932). The converse experiment, keeping breeding season animals in daylight of winter duration, was also attempted by Bissonnette (1933), but the results were inconclusive. A somewhat similar experiment was therefore carried out in London, under the very stringent conditions of keeping the animals in total darkness except at the time of feeding. The results offer little support to the theory that length of daylight has any controlling influence on normal sexual periodicity.

Even in daylight in clear conditions the driver's visibility, both forward and rearwurd, is restricted by the structure of the vehicle. Important sections of the view can be obscured ; thus a windscreen pillar can obscure a pedestrian Or cyclist until it is too late to avoid an accident. A given vehicle has certain visibility characteristics. The work described in this paper is the measurement of these characteristics for a range of vehicles. The method of measurement is based on an American technique in which two lamps are positioned to correspond with the eyes of an average driver. The visibility is measured by moans of the shadows cast by body pillars, bonnet, etc., and by the light reflected rearwards by the mirror. Both forward and rearward visible areas can be interpreted as plans of visible areas on the ground, In the choice of eye position, consideration was given to the position of the eyes relative to the teat and to the position of the seat in its travel, The seat is positioned with reference t...

This paper outlines the theory behind the development of a set of tables for the field reduction of azimuth observations on elongating daylight stars. The merits of the method, namely that the results are independent of latitude and that the calculations are very much simplified, are brought out. The use of the tables is discussed and samples are presented.

This paper covers several of the significant "inservice improvements," including the introduction of simulation study techniques, new displays, and automatic data processing that have been taken to meet the air traffic control requirements. A review of the three basic simulation methods: graphical, dynamic, and fast time is provided together with a description of the dynamic simulation facilities at the Technical Development Center of the Federal Aviation Agency (FAA), Indianapolis, Ind. The requirements for daylight viewing displays and the programns conducted to obtain TV types of radar displays are included. The report concludes with the introduction of digital computers to perform certain data processing functions.

This paper presents correlations between the abnormal earth currents noted during magnetic storms and transoceanic radio transmission on both long and short waves. The radio transmission data were collected on the telephone circuits operating between New York and London and between New York and Buenos Aires. The earth current data were collected on two Bell System lines extending approximately a hundred miles north and west from New York. The results of this work establish facts which have been known in a general way for some time. The direction of flow of abnormal earth currents in the neighborhood of New York seems to be along a northwest-southeast line. Coincident with such abnormal currents are periods of poor short-wave radio transmission. However, on long waves, daylight transmission over transatlantic distances is improved. On the short-wave circuit to Buenos Aires, transmission is adversely affected but only to a moderate extent.

Summary This paper, read in Utrecht on October 14th 1965, deals with the average occupancy of cars outside urban areas. During the years 1962 and 1963 more than 500 samples (each consisting of 150 cars) have been taken on two points of the dutch road-system. The samples covered the different months, days (sundays, Saturdays and week-days) and hours (except those without daylight). The average occupancy turned out to be 1.8 on week-days (with a minimum of 1.4), 2.5 on Saturdays (with a minimum of 2.1) and 3.1 on Sundays (the over-all average for all days being 2.1). These results seem to be representative for the whole dutch car traffic as is shown by comparison with observations on other points and other data. Comparison of the seasonal, weekly and hourly patterns of the average occupancy with those of the car traffic density enable to draw conclusions about the responsibility of different kinds of traffic (commercial and commuter traffic versus social traffic) for congestion and for the construction and maintenance cost of the road-system.

This paper reports the results of a study made to determine the nature of microclimatic changes induced by a wind barrier and the nature of dry bean response to the induced microclimate in an irrigated field in western Nebraska. The study was conducted during the growing seasons of 1962 and 1963. Shelter sharply reduced wind movement over the canopy of the plants. A new diurnal pattern of air and soil temperature and of vapor-pressure was generated in the shelter. The plants responded by larger size and higher yield during both years and in greater leaf area during the first season. Evaporation in the shelter was reduced but the plants remained more turgid throughout the daylight hours and resisted stomatal closure allowing greater transpiration and consequently more rapid withdrawal of soil moisture. Data are presented which show that CO2 supply need not be limited in the shelter because of reduced wind passage over the plant and that greater potential photosynthesis in the shelter consequent upon the more open condition of the stomates can be realized.

The interest among those working in the museum field of photochemical damage appears quite justly to have been directed chiefly towards the effects of artificial light sources. One reason perhaps is because this is more easily controlled than is natural light. The purpose of this paper is to describe (a) the problem of controlling daylight to be used partly for illuminating exhibits and partly for the visiting public viewing the exhibits against and as part of the exterior landscape, and (b) the solution proposed. The locale of the problem is a museum building under construction in a substantially broad area of handsome public buildings, wide avenues, drives and lawns. The long dimension of the building is oriented east and west. It is designed to accommodate visitors expected to number more than 5,000,000 persons annually. Architectural and esthetic considerations required the provision of large windows, 16 ft. high by 30 ft. wide, on three floors of the east and west fa~ades. This provision posed the problem of regulating their use by curtains in order to 'protect any museum materials which might be exhibited near them in the lifetime of the building... the problem of old costumes being probably the most severe that can be anticipated'-the alternative being the blocking up of window openings.

For many years past the subject of plant distribution in relation to the illumination of the site has been of interest to botanists. Results obtained using photochemical and photographic methods have been summarized by Wiesner (1907) and by Riibel (1928). Dorno (1919, 1928) has studied the measurement of daylight by a variety of methods. Klugh (1925, 1927) has given a general review of recent literature, and described a photographic method with a neutral wedge and rhodamine B paper.

It has been suggested that the C.I.E. standard observer data for colorimetry may be seriously in error below 4600 ?. In this paper it is shown that the fluorescent lamp can be of particular value in checking the data at 4358 ? since fluorescent lamps and standard illuminants can form metameric pairs with different spectral distributions in the blue-violet and principally at 4358 ?. The check is made by visual comparison of the metameric pair and correlating the chromaticity so obtained for the fluorescent lamp with that obtained by computation from the spectral distribution. Measurements on warm white and daylight fluorescent lamps gave reasonable correlation with the C.I.E. data but not with the Wald-Gibson-Tyndall average data.

This paper presents the results of a study of an apparent inter-relationship between radio reception and changes in the earth's magnetism. The results show that for long-wave daylight reception over great distances 4,000 to 7,100 km) there is in general a variable but definite increase in the intensity of the received signal following the height of severe magnetic disturbance. This increase reaches its maximum in from one to two days and disappears in from four to five days. For moderate distances (250 to 450 km) there is an increase in the intensity of the received signal noticeable before as well as after the magnetic storm reaches a maximum. These changes in intensity cover periods from two to four days both before and after the magnetic storm reaches its height.

This paper gives monthly averages of daylight signal intensity at Washington for 1929, as received from a number of European and American low-frequency stations. Several of the stations formerly measured have ceased to transmit regularly at hours sutitable for all-daylight transmission paths and their measurement has therefore been discontinued. The annual average field intensities of the European stations have not shown much change since last year, but the atmospheric disturbances have increased.

This paper gives analyses of observations of long-wave transmission across the Atlantic over a period of about two years. The principal conclusions which the data seem to justify are as follows: 1. Solar radiation is shown to be the controlling factor in determining the diurnal and seasonal variations in signal field. Transmission from east to west and west to east exhibit similar characteristics. 2. Transmission in the region bordering on the division between the illuminated and the darkened hemispheres is characterized by increased attenuation. This manifests itself in the sunset and sunrise dips, the decrease in the persistence of high night-time values in summer and the decrease in daylight values during the winter. 3. Definite correlation has been found between abnormal radio transmission and disturbances in the earth's magnetic field. The effect is to decrease greatly the night-time field strength and to increase slightly the daylight values. 4. The limit of the high-night-time value of signal field strength for transatlantic distance is essentially that given by the Inverse Distance Law. The normal daylight field strengths obtained in these tests can be aproximated by a formula of the same form as those earlier proposed but with somewhat different constants. 5. The major source of long wave static, as received in both England and the United States, is indicated to be of tropical origin. 6. In general, the static noise is lower at the higher frequencies. At night the decrease with increase in frequency is exponential. In day-time the decrease with increase in frequency is linear in the range of 15 to 40 kilocycles. The difference between day and night static is, therefore, apparently due largely to daylight attenuation. 7. The effect of the static noise in interfering with signal transmission. as shown by the diurnal variations in the signal-to-noise ratio, is found to be generally similar on both sides of the Atlantic. 8. Experiments in both the United States and England with directional receiving antennas of the wave antenna type show an average improvement in the signal-to-static ratio of about 5 as compared with loop reception.

The biochemist's use of radioactive isotopes for tagging molecules is well known and widely appreciated; but these newly available materials can also be used to advantage in ecological studies which involve tracing the position and movements of individual animals. Harmless radioactive tags permit many types of ecological and behavior studies to be carried out under natural conditions without the presence of a human observer. I wish to describe one successful application of this method to homing experiments with wild birds, and suggest the scope of its potential usefulness in other types of investigation. In most studies of the homing of birds it has been necessary for an observer to watch the nest of each bird throughout the daylight hours between its release and its return. When planning such experiments in the Arctic it was clear that the continuous daylight would increase the difficulties of visual checking; and an automatic recording device was therefore developed to register the time of return of an individual bird, as distinguished from its mate or others of the same species. Radioactive tagging offered the great advantage of specificity; no natural event and scarcely any type of apparatus failure could give a false indication of the marked bird's return. The radioactive material was attached to the conventional aluminum bird band, and a recording radiation meter was operated near the nest to measure the slight rise in radiation intensity at the time of a tagged bird's return. The actual instrument consisted of a conventional radiation detector (Nuclear Instrument and Chemical Corporation Model 2610) with an extra stage of amplification so that 0.2 milliroentgen per hour produced a fullscale deflection of an Esterline-Angus Model AW recording milliammeter. The clockwork of the meter and the dry batteries for the amplifier would operate eight days without attention. The instruments were housed in a metal box and the Geiger-Mueller tube and cable were protected by rubber tubing, so that the whole assembly operated well even when half submerged in water. The recording meter drew a baseline the position of which was determined by the intensity of natural background radiation; if the line rose to a clearly higher level the return of the tagged bird to its nest was registered in unequivocal fashion. The apparatus was used primarily with the semipalmated plover Charadrius semipalmatus; but it would be equally applicable to any other situation in which it was desirable to record an animal's arrivals and departure within a small area. For tagging animals in this way isotopes emitting gamma rays are preferable to alpha or beta ray emitters, because of the greater range at which gamma rays can be detected after penetrating through any solid material that may come between the tag and the detecting instrument. Furthermore, alpha and beta radiations increase the radiation dose inflicted on the tagged animal without materially facilitating the instrumental detection of the tag from any considerable distance. Hence in this paper only gamma radiation will be considered as a means of detecting the radioactive tag. The method has two inherent limitations: only one animal at a time can be 1 This work was supported by a research contract between the Office of Naval Research and Cornell University, and was based at the Arctic Research Laboratory, Point Barrow, Alaska. This aid is gratefully acknowledged, together with the cooperation and encouragement of Dr. Laurence Irving.

In this paper is presented an analysis of the natural illumination data assembled at Pretoria (Union of South Africa) during 1955. The results are the first available for the Southern Hemisphere regarding the intensities of the total luminous flux, through a horizontal surface, and also of its component due to skylight. The basic instrumentation and the record standardization procedures have been discussed in a previous contribution. The main results are compared with those derived at Kew (England), Tashkent (U. S. S. R.), Vienna (Austria), and Washington (U. S. A.).

Recurrent phenomena in living things such as the yearly fall of the leaf, or the daily opening and closing of certain flowers, is a matter of common observation. Many other less obvious cases have been disclosed in biological research; such as the annual opening and closing of lenticels, and the diurnal periodicity of secondary thickening (Kaiser, 1879) and of osmotic pressure (Ursprung and Blum, 1916); but so far as I am aware, annual rhythm has not been demonstrated for any form of irritability, and neither annual nor diurnal rhythm for any tropism. The present work attempts to show that the perception of, and response to, gravity are not of the same intensity at all periods, but vary both with the time of day and season of the year. During the course of a series of researches on geotropism in the Pteridophyta the first of which was communicated to the Royal Society in 1921 (Prankerd, 1922) the impression was gained that the plants were less responsive during the winter, and it was decided to investigate the matter quantitatively for the fern whose behaviour to gravity was best known, namely Asplenium bulbiferum . The work was performed in daylight, partly because a dark room at constant temperature for long periods of time was impracticable, but more especially because it was desired to keep the plants under perfectly natural conditions, and thoroughly healthy. That they were so was shown by their general appearance, growth, and reproduction. Precautions against heliotropic curvature were taken as fully explained previously (Prankerd, 1922). The temperature of the research greenhouse in which the plants were grown was usually near 20° C, and all experiments recorded in this paper were performed at 20° ± 1°, and at a relative humidity of about 80%. Hence, with the exception of a some­what lower average temperature at night, and of course less daylight in the winter, every external condition to which the plants were subjected would seem to have been the same throughout the year, and their behaviour as far as could be seen, for example, in growth and reproduction, was fairly uniform. Previous work has shown that the irritability of the frond to gravity varies with its development (Waight, 1923). It is very low in the early stages, requiring long periods of stimulation, and as response is also slow, experiments are very lengthy. In its later stages the frond is somewhat uncertain in its behaviour, and more sensitive to light stimulus. The middle stages, i.e ., “late infant” and early “adolescent” ( see below), have therefore always been employed. They have been more fully studied, are the most reactive, and are more constant, at least than the later stages.