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In the summer months (May, June, and July) the temperature curve during the day hours, from 8 a.m. to 8 p.m., hardly differs from a curve of sines, the first component being more than ten times as large as any of the others, which therefore influence the temperature, relatively, very little.

The relation of the epoch of the first maximum of the component of the third order to the time of sunrise is decidedly marked, the former occurring, on the average, about 12°, or 48m. after sunrise; the mean deviation of the interval from that amount being only 7°, or 28in.

The periodical variation in the position of the maximum leads, during the winter months, to a positive maximum of this component about I p.m., which is combined with negative maxima four hours earlier and later, which correspond to the riduced temperature in the mornings and afternoons of the shorter days. In like manner, in the summer months, when this component has a negative maximum about I p.m., instead of a negative minimum, as in winter, there will be two positive maxima, one four hours earlier, the other four hours later, corresponding to the higher temperature in the mornings and afternoons of the longer days.

It will be seen that these positions of the midsummer and midwinter maximum phases correspond respectively to days of 16 hours with nights of 8 hours, or days of 8 hours and nights of 16 hours, and that at these seasons, when the variations of temperature, due to these differences, are greatest, the amplitudes of this component are also the greatest. At the equinoxes, with 12-hour days and nights, the component becomes a minimum ; and at this season the change in the position of the maximum takes place as already noticed.

It might be supposed that an analogous relation between the fourth component and the occurrence of days of 18 hours, combined with nights of 6 hours, and vice versa, is likely to arise. But the data are not forthcoming to test this.

In the summer months the time of mean temperature is nearly where the first component becomes zero, the second and third components then balancing one another.

In the winter the time of morning mean temperature is later than in summer, and occurs when a positive value of the first component is equal to a negative value of the second.

The time of afternoon mean temperature throughout the year is somewhat either before or after 7 p.m., and almost exactly coincides with the time when the first and second components are equal, with opposite signs.

In the summer the time of absolute minimum is between the hours of 3 a.m. and 6 a.m., during which the whole of the components are negative.

Sunrise in December is about an hour and a half before the time of mean temperature; while in June it is more than four hours earlier.

Sunset in December is rather more than three hours before the time of mean temperature; in June it is about half an hour after that time.

The rationale of some of the empirical rules for obtaining the mean daily temperature from a limited number of observations is supplied by reference to the harmonic expressions for the hourly deviations of temperature from the mean value.

In the first place, it will be seen that by adding together the harmonic expressions for any two hours twelve hours apart, the whole of the odd components disappear, and that the sum is twice the mean value, added to twice the sum of the even components of the selected hours, which are equal.

By taking the mean of observations at any four hours, at intervals of six hours, both the odd components and those of the second order will disappear, and the result will only differ from the true mean by the amount of the fourth component for the selected hours.

So, if the mean of any three hours at equal intervals of eight hours be taken, the sums of the first, second, and fourth components will disappear, and the result will only differ from the true mean by the amount of the third component for the selected hours, which in no case can be so much as .

2. Temperature at the Seven Observatories.

The examination of the tables will show that in their main characteristics the results closely resemble those for Greenwich, and it will not be necessary to discuss them in any detail.

The amplitude of the component of the first order is, however, in all cases less than that observed at Greenwich, the

lowest values being those for Valencia and Falmouth, no doubt due to their position on the sea coast, for which stations the means for the years are 2° 28 and 235 compared with 5'10 at Greenwich.

The Kew values most resemble those at Greenwich, but the mean maximum at Kew is more than I less, and the mean for the year less.

The mean values of for the seven observatories lie between 205 and 220, that for Greenwich being 214. The means of the summer values are about 3 or 4 less than the mean of the year, and of the winter values as much above it. as in the case of Greenwich.

The amplitude of the first component conforms approxi mately, but not so closely as at Greenwich, with the sine of the sun's meridian altitude, but with a flattening of the curve in the summer months, and a tendency at some of the stations to a maximum value in May.

The components of the second and third orders, beyond which the analyis is not carried for these observatories, conform in all important respects to those for Greenwich, the numerical values of the latter being, however, in all cases somewhat higher. The epochs of maximum follow the same laws, with an increased divergence of the summer epoch from that of the winter at the more northern stations.

In order to test, and in some degree throw light, on the character and significance of the harmonic components of temperature that have been under discussion, and bearing in mind that they cannot be considered to represent separate effects of physical forces operating at the assumed periods of the components, I have, at the suggestion of Prof. G. Darwin, calculated the harmonic components from a curve representing an intermittent heating action such as that of the sun, continued only during a portion of the day, and commencing and ending abruptly at sunrise and sunset.

All cooling effects have been disregarded, and the sun's direct heating action is assumed to be proportional to the sine of his altitude, the power of a vertical sun being taken to be 10. Having calculated the sun's altitude for each hour of the day, for midwinter, the equinox, and midsummer, for certain selected latitudes, the corresponding heating effects have been computed to which the usual method of analysis has been applied.

The comparison of the results thus obtained with the corresponding components derived from actual observation at places having nearly the same latitudes as those selected, establishes their close similarity, and the conclusion is unavoidable, that, although both in the actual and hypothetical cases the harmoni components when combined are truly representative of the peculiar forms of the curves from which they were derived, this affords no evidence of the existence of recurring cycles of action corresponding to the different components, but that the results are, to a great extent, due to the form of the analysis.

The diurnal curve of temperature is not symmetrical in relation to the mean value, the maximum day temperature being much more in excess than the minimum night temperature is in defect. To adjust the first component, which is symmetrical about its mean value, to the actual unsymmetrical curve, it must be modified by the other components. That of the second order, which has one of its maxima not far removed from the minimum of the first order, supplies the chief portion of the compensation due to this cause.

Further, from the character of the analysis, when the diurna! curve is symmetrical on either side of the hour half way between noon and midnight-that is, when the day and night are equal in length-the third component becomes zero. Any departure from this symmetry introduces a component of the third order, with the result that with a day shorter than 12 hours one maxi mum will fall in the day between 6 a.m. and 6 p.m., and the other two in the night between 6 p.m. and 6 a.m.; while with a day longer than 12 hours, two maxima will occur in the day and only one in the night. In the former case the negative por tions of the component correspond with the reduced morning and afternoon temperatures of the short day, and in the latter the two positive phases correspond with the higher temperature of the mornings and afternoons of the longer day.

These conclusions are in conformity with those previously indicated.

The available data are insufficient to enable us to say whether the corresponding results connected with the fourth component are as fully supported by observation as in the case of the third, but the facts so far as they go confirm this view.

Anthropological Institute, April 11.-Prof. A. Macalister, President, in the chair.-Mr. G. M. Atkinson exhibited a cranium and several metal ornaments found by Mr. A. Michell Whitley and Dr. Talfourd Jones in a grave at Birling, near Eastbourne, Sussex. The peculiar coffin-like shape of the skull seemed to point to its belonging to the early Saxon period, while the metal ornaments were assigned to the late Roman or immediately post-Roman age. -Mr. R. Duckworth read a paper on two skulls from Nagyr, recently added to the Cambridge University collection. One of them is a female skull, and is remarkably dolichocephalic, the cephalic index being 69'94. The other skull is that of an adult male.-Prof. Macalister read

a paper on Egyptian mummies. He described the manner in which they were prepared, the unguents used by the Egyptians

and the various cloths in which the mummies were rolled. He explained the difference between the Egyptian cloths and those manufactured in England at the present day, and said that the object of using so few threads in the weaving was for the purpose of saving time and trouble. The material at the same time was brought to a high state of perfection as a manufacture, and indeed might even compare with some of the finest linen productions at the present day. Specimens of cloth were exhibited and the author stated, on the authority of a linen manufacturer, that there was only one specimen of linen manufacture in the United Kingdom which could be recognised as of similar structure to the Egyptian productions.-A paper on Damma Island and its natives by P. W. Bassett Smith, R. N., was also read.

Geological Society, April 12.-W. H. Hudleston, F. R. S., President, in the chair.-The following communications were read-On some Paleozoic Ostracoda from Westmoreland, by Prof. T. Rupert Jones, F. R. S. In 1865 the author determined for Prof. Harkness some fossil Ostracoda which he had obtained from the Lower Silurian rocks of South East Cumberland and North-East Westmoreland, and subsequently other specimens mentioned by Harkness and Nicholson in 1872. In 1891 Prof. Nicholson and Mr. Marr submitted a series of similar microzoa from the same district; and the author now endeavours to determine their specific alliances, and revises the list of those previously collected. He has to notice about eleven forms of Primitia, Beyrichia, Ulrichia, Echmina, and Cytherella-several of them being closely allied as varieties, but all worthy of study as biological groups, such as have been illustrated from other regions by writers on the Ostracoda, with the view of the exact determination, if possible, of species and genera, of their local and more distant or regional distribution, and of their range in time. -On some Paleozoic Ostracoda from the Girvan district in Ayrshire, by Prof. T. Rupert Jones, F. R.S. This paper aims at the completion of the paleontological account of the Girvan district, so far as the Ostracoda are concerned; and follows up the researches indicated in the "Monograph of the Silurian Fossils of the Girvan District in Ayrshire," by Nicholson and Etheridge, vol. i., 1880. In about a dozen pieces of the fossiliferous shales, submitted for examination some few years ago, the writer finds nearly thirty specimens of Primitia, Beyrichia, Ulrichia, Sulcuna, and Cypridina which show interesting gradations of form, not always easy to be defined as specific or even varietal, but valuable as illustrating modifications during the life-history of individuals, thus often leading to permanent characteristics of species and genera. Like those formerly described in Nicholson and Etheridge's "Monograph, the specimens have all been collected by Mrs. Elizabeth Gray, of Edinburgh. The reading of these papers was followed by a discussion, in which the President, Mr. Marr, and the author took part. On the dwindling and disappearance of limestones, by Frank Rutley. The existence of chert between two sheets of eruptive rocks at Mullion I-land seemed to the author to require some explanation. Cherts are usually associated with limestones, and the absence of limestones in many cases where cherts are found points to their removal by underground waters. The older the limestone the greater the probability of its thickness having dwindled. The thicknesses of the Ordovician, Silurian, Devonian, and Carboniferous Limestones seem to be in the ratio of 1: 15: 15: 100. Many limestones once existing in Archæan rocks may have disappeared, as also limestones in later rocks. The author comments on the difficulty of distinguishing some cherty rocks from felstones. Two appendices are added to the paper, the first on the transference of lime from older to newer deposits, and the second on the formation of

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nodular limestone-bands.-This paper gave rise to a discussion in which the President, Prof. Hull, Mr. Walford, Prof. Judd, General McMahon, Prof. T. R. Jones, Prof. Hughes, Mr. H. W. Monckton, Dr. G. H. Hinde, and the author took part. On some Bryozoa from the Inferior Oolite of Shipton Gorge, Dorset, Part II., by Edwin A. Walford.

Royal Meteorological Society, April 19.-Dr. C. Theodore Williams, President, in the chair. The following papers were read:-The direction of the wind over the British Isles, 1876-80, by Mr. F. C. Bayard. This is a reduction on an uniform plan of the observations made twice a day, mostly at 9 a.m. and 9 p.m., at seventy stations during the lustrum 187680; and the results are given in tables of monthly and yearly percentages.-Notes on two photographs of lightning taken at Sydney Observatory, December 7, 1892, by Mr. H. C. Russell, F. R. S. These photographs were taken with a halfplate view lens, mounted in a whole plate camera, and, as a matter of course, there is some distortion at the edges. Both photographs show the gaslights in the streets as white specks, the specks being circular in the centre and crescent-shaped in other parts of the plate owing to distortion. The lightning flashes are also distorted. Mr. Russell believes that this distortion may account for the so-called "ribbon" flashes, which are seen in many photographs of lightning. He has also made some measurements of the length and distance of the flashes, and of the intensity of the light.-Notes on lightning discharges in the neighbourhood of Bristol, 1892, by Dr. E. H. Cook. The author gives some particulars concerning two trees in Tyntesfield Park, which were struck by lightning, one on June 1 and the other on July 18, and also some notes concerning a flagstaff on the summit of Brandon Hill, which was struck on October 6.— Constructive errors in some hygrometers, by Mr. W. W. Midgley. The author, in making an investigation into the hygrometrical condition of a number of cotton mills in the Bolton district, found that the mounting of the thermometers and the position of the water receptacle did not by any means conform to the regulations of the Royal Meteorological Society, and were so arranged that they gave the humidity results much too high. The Cotton Factories Act of 1889 prescribes the maximum weight of vapour per cubic foot of air at certain temperatures; and the author points out that if the instruments for determining the amount present in the mills have an error of 20 per cent. against the interests of the manufacturer, it is necessary that the makers of the mill hygrometers should adopt the Royal Meteorological Society's pattern for the purpose.


Academy of Sciences, April 17.-M. Loewy in the chair. -Note on the observation of the partial eclipse of the sun of April 16, 1893, by M. F. Tisserand.-On the observation of the total eclipse of the 16th inst., by M. J. Janssen.— Effects of the drought upon this year's crops; reply to M. Demontzey's note on the planting of the highlands, by M. Chambrelent.-Expansion of water at constant pressure and at constant volume, by M. E. H. Amagat. At pressures higher than 200 atmospheres water has no maximum density above zero. At the lower temperatures, contrary to what takes place in the case of other liquids, the coefficient of expansion increases with the pressure. This increase is gradually effaced as the temperature rises, is sensibly zero at 50° or 60°, and changes sign for higher temperatures. If water is kept at a constant volume the pressure increases rapidly with the temperature. Thus, for unit volume the coefficient of pressure increases fourfold between 10° and 100°, and the variation is proportionately even more rapid between o° and 10°-On the structure of simple finite and continued groups, by M. Cartan. -On a simple group with fourteen parameters, by M. F. Engel. Demonstration of the transcendental nature of the number e, by M. Adolf Hurwitz.-Comparison of the international meter with the wave-length of cadmium light, by M. Albert A. Michelson.-Photography of gratings engraved upon metal, by M. Izarn. It is possible to reproduce opaque gratings engraved upon metal in a manner analogous to the reproduction of transparent ones already described. On covering such a grating with a layer of bichromated gelatine, and exposing to the sun through this layer, a grating effect is produced which, although rather feeble, is due to successive differences of structure corresponding to the rulings. These differences of structure are probably due to stationary reflected waves, and

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