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title, published in 1865; but in the matter of rainfall Studnicke has had special opportunities which have enabled him, to say nothing of the lapse of the past ten years, to present the fullest particulars and material. Thirty-eight stations were indeed represented in the memoir of Sonklar on the hyetography of Austria; he was, however, unable, even with this number of stations, to properly represent the southeastern portion of Bohemia. The gaps that were necessarily found in Sonklar's and Kreil's works have been filled up by Studnicke, who was three years ago put in charge of the meteorological section of the committee for the scientific survey of Bohemia, and who has been instrumental in adding about fifty new stations to those already existing. Especial study was made in the neighborhood of Prague, where four new stations were established, in order to elucidate the differences in the records of the older observations.--Sitzb. K. Böhm. Gesellschaft, 1874, 62.

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MOISTURE IN THE ATMOSPHERE,

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Mariè Davy states that there is kept in active service in the meteorological observatory at Mont-souris a collection of apparatus for investigating, in a general way, certain physical problems of the atmosphere, especially the quantity of aqueous vapor contained therein. The apparatus consists principally of a large telescope, with silvered objective and a photometric ocular. This ocular consists of a Foucault polarizing prism, behind which is placed a double-refracting analyzer movable about the centre of a graduated circle. By the use of this apparatus we measure the ratio of the intensity of the light given from the sun, and from any part of the atmosphere in its immediate neighborhood; this ratio varies with the state of the sky. A similar operation would give the measure of the apparent intensity of the solar spots. A second telescope of smaller dimensions is mounted equatorially. Its objective is uncovered, and its ocular is similar to the preceding. A disk of white enamel is fixed horizontally on a pillar; at the side of the disk is found a smaller one of copper, which projects its shadow upon the enameled disk when illuminated by the sun. This shaded circle is then only lighted by the diffused light of the sky, while the neighboring parts receive also the direct rays of the sun. The

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telescope previously described, or the photometer, gives then the ratio of the intensity of the two lights. Some white disks with black centres placed at various distances give with precision the degree of transparency of the air in day-time. The transparency of the sky during the night can also be found by the same instrument; but the results differ according as the moon is or is not above the horizon. The thermo-electric actinometer of Dessaine has also been modified in its applications by Mariè Davy. The cyanometer of Arago is also made use of.- Bulletin Mensuel Observatoire de Mont Souris, 1875, 129.

THE OBSERVATION OF POLAR BANDS.

The Wochenschrift, published for so many years by Dr. leis, of Münster, has lately been transferred to the editorship of Dr. Herman J. Klein, of Cologne, well known to lovers of astronomy by his numerous popular essays. In his hands its interest will not fail of being maintained. Two recent articles by him are especially worthy of notice, one on the importance of observations of that form of clouds ordinarily known as polar bands, which have acquired a new interest owing to the observations and theories of Prestel and Hildebrandsson. another article Dr. Klein calls attention to the project long since made by Dr. Falb of using the asteroids as a medium for determining the brightness of the faintest fixed stars.-Klein's Wochenschrift, 1875.

TIME OF SETTING SELF-REGISTERING INSTRUMENTS. In the report of the meteorological section of the Leicester Literary and Philosophical Society, we learn that the time of setting the self-registering instruments has been altered from 9 A.M. to 9 P.M. This alteration has been made in consequence of the recommendation of the Vienna Congress, which has been adopted by the official and by all the principal private observatories of England. A new and more complete graphic method has also been adopted for displaying the daily readings of the meteorological instruments. By this method a whole month's daily readings are now exhibited in tabular form on a single sheet.—Leicester Literary and Philosophical Society's Report, 1875.

title, published in 1865; but in the matter of rainfall Studnicke has had special opportunities which have enabled him, to say nothing of the lapse of the past ten years, to present the fullest particulars and material. Thirty-eight stations were indeed represented in the memoir of Sonklar on the hyetography of Austria; he was, however, unable, even with this number of stations, to properly represent the southeastern portion of Bohemia. The gaps that were necessarily found in Sonklar's and Kreil's works have been filled up by Studnicke, who was three years ago put in charge of the meteorological section of the committee for the scientific survey of Bohemia, and who has been instrumental in adding about fifty new stations to those already existing. Especial study was made in the neighborhood of Prague, where four new stations were established, in order to elucidate the differences in the records of the older observations. ---Sitzb. K. Böhm. Gesellschaft, 1874, 62.

MOISTURE IN THE ATMOSPHERE. Mariè Davy states that there is kept in active service in the meteorological observatory at Mont-souris a collection of apparatus for investigating, in a general way, certain physical problems of the atmosphere, especially the quantity of aqueous vapor contained therein. The apparatus consists principally of a large telescope, with silvered objective and a photometric ocular. This ocular consists of a Foucault poiarizing prism, behind which is placed a double-refracting analyzer movable about the centre of a graduated circle. By the use of this apparatus we measure the ratio of the intensity of the light given from the sun, and from any part of the atmosphere in its immediate neighborhood; this ratio varies with the state of the sky. A similar operation would give the measure of the apparent intensity of the solar spots.

A second telescope of smaller dimensions is mounted equatorially. Its objective is uncovered, and its ocular is similar to the preceding. A disk of white enamel is fixed horizontally on a pillar; at the side of the disk is found a smaller one of copper, which projects its shadow upon the enameled disk when illuminated by the sun. This shaded circle is then only lighted by the diffused light of the sky, while the neighboring parts receive also the direct rays of the sun. The telescope previously described, or the photometer, gives then the ratio of the intensity of the two lights. Some white disks with black centres placed at various distances give with precision the degree of transparency of the air in day-time. The transparency of the sky during the night can also be found by the same instrument; but the results differ according as the moon is or is not above the horizon. The thermo-electric actinometer of Dessaine has also been modified in its applications by Mariè Davy. The cyanometer of Arago is also made use of.-- Bulletin Mensuel Observatoire de Mont Souris, 1875, 129.

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THE OBSERVATION OF POLAR BANDS. The Wochenschrift, published for so many years by Dr. Heis, of Münster, has lately been transferred to the editorship of Dr. Herman J. Klein, of Cologne, well known to lovers of astronomy by his numerous popular essays. In his hands its interest will not fail of being maintained. Two recent articles by him are especially worthy of notice, one on the importance of observations of that form of clouds ordinarily known as polar bands, which have acquired a new interest owing to the observations and theories of Prestel and Hildebrandsson. In another article Dr. Klein calls attention to the project long since made by Dr. Falb of using the asteroids as a medium for determining the brightness of the faintest fixed stars.--Klein's Wochenschrift, 1875.

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TIME OF SETTING SELF-REGISTERING INSTRUMENTS. In the report of the meteorological section of the Leicester Literary and Philosophical Society, we learn that the time of setting the self-registering instruments has been altered from 9 A.M. to 9 P.M. This alteration has been made in consequence of the recommendation of the Vienna Congress, which has been adopted by the official and by all the principal private observatories of England. A new and more complete graphic method bas also been adopted for displaying the daily readings of the meteorological instruments. By this method a whole month's daily readings are now exhibited in tabular form on a single sheet.-Leicester Literary and Philosophical Society's Report, 1875.

ON THE WET AND DRY BULB THERMOMETER. One of the most serious defects in the use of the August Psychrometer, or the wet and dry bulb thermometer, is due to the fact that the radiation from surrounding objects affects the covered thermometer quite differently from its effect upon the naked. In order to remedy this defect, Overbeck, of Batavia, proposes to place the instrument within a shelter formed of thin upright sheets of metal, so that the direct rays of the sun can not strike the instrument, Metal has some advantages over the wooden screens usually employed.Tijdschrift Voor Nederlandsch Indie, Batavia, 1874, 120.

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PERIODICITY OF THE AURORA,

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Professor Fritz, whose great catalogue of all known auroras was published in 1873, has recently communicated to the Natural History Society of Zurich an investigation into the relative periodicity of auroras and solar spots. He finds the differences between the years of greatest auroral and sunspot frequency are sometimes positive and sometimes negative; but in general the maximum of the auroras occurs seven tenths of a year after the maximum of sun-spots, while the minimum of auroras occur three tenths of a year before the minimum of the sun-spots. These differences, however, are too uncertain to be spoken of as a definite law. As regards the greater period of 55 years, he concludes that for the present we can not improve upon the determination made by himself in 1865, when he showed that this periodicity could be best represented by assuming that it coincided with five of Wolf's 11-year periods, or 55,55 years. He considers it also probable that there is a still longer period of 222 years in auroras, which, of course, we are unable to detect in the solar spots for want of observations. Vienna Zeitschrift für Meteorologie, X., 317.

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THE NEW PHYSICAL OBSERVATORY NEAR ST. PETERSBURG.

Dr. Wild, of St. Petersburg, Director of the Physical Central Observatory, gives an account of the establishment near St. Petersburg, at the well-known summer resort Pavlosk, of an auxiliary observatory, at which it is hoped numerous in

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