132 



NATURE 



\_ytme lO, 1 8 So 



the perturbations, from the observations made at the comet' 

 appearance in the summer of 1S19. He infers from his researched 

 apon Winnecke's comet a value for Encke's force designated by 

 U, differing little from that assigned by Encke from his discussion 

 of the motion of his comet, the more satisfactory considering that 

 much latitude must be allowed in this direction. He further 

 observes that with U = -r,\-(s the effect upon the motion of Faye's 

 comet would be so small that it is necessarily mixed up with 

 uncertainty in the values of the perturbations ; it will be remem- 

 bered that Prof. Axel-MtiUer, who has laboured so admirably to 

 follow up with every precision the motion of Faye's comet, has 

 not, since his computations assumed their present refined form, 

 been able to detect any abnormal effect upon it. 



With regard to a diminution in the mass of Jupiter it is to be 

 remarked that all the newer reliable determinations have con- 

 firmed the value deduced by Bessel from the elongations of the 

 satellites, including that inferred by Prof. Krueger from the 

 perturbations of Themis, and that which Dr. Axel-MoUer has 

 found from his researches on the motion of Faye's comet. Such 

 diminution, therefore, appears inadmissible. 



The liMPERiAL Observatory, Strassburg. — In a commu- 

 nication to the Astronomisc/u-s Gcselhchaft Prof. Winnecke has 

 given details of the construction and instrumental equipment of 

 this new establishment, which we cannot doubt, under his skilful 

 and energetic direction, is destined to take its place amongst the 

 most prominent of astronomical institutions. The principal 

 instruments are — (l) the meridian circle, with object-glass of 6'4 

 inches aperture, which has been constructed by Repsold and was 

 completed several years since ; (2) the alt-azimuth, of 5*35 inches 

 aperture and 4'g feet focal length, also by Repsold ; (3) the 

 refractor, of 19 '2 inches aperture and 23 feet focal length, by 

 Merz, but mounted by Repsold, the object-glass being found to 

 be of great excellence; (4) an "orbit-sweeper," constructed 

 according to the design of Sir George Airy, as explained in the 

 Monthly Notices of the Royal Astronomical Society, vol. xxi. 

 p. 158 ; this is, so far as we know, the only instrument of the 

 kind yet mounted, and has been used for some time by Prof. 

 Winnecke in the provisional observatory at Strassburg ; the 

 .aperture of the object-glass is 6'4 inches, which is not greater 

 than it is essential to provide for the advantageous use of the 

 peculiar mounting. We may hear of the application of the 

 "orbit-sweeper" to the search (which it is not too soon to com- 

 mence) for the comet of 1812, and later on for Olbers' comet of 

 1815, neither of which bodies will admit of accurate prediction. 

 A plan of the buildings and grounds accompanies Prof. 

 Winnecke's notice in the Vicrlcljahrsschrijt. 



The Companion of Sirius. — Mr. Burnham publishes mean 

 results of numerous measures of the small companion of Sirius 

 made with the iS inch refractor at Chicago in the years 1S77-80. 

 We subjoin them with the errors indicated for Prof. Auwers' 

 ephemeris in his Uiiternichnjigai iibcr z'crandirliche Eigcn- 

 tiivegmigen : — 



r,^^.^ n-.:.:._ Error cf n:,._„ Error of 



i878'oi ... 52-4 



1879-13 ... 507 



iSSo'ii ... 48-3 



-f 6-0 



+ 5-5 

 + 57 



10-83 

 10-44 



lO'OO 



-0-78 

 -0-77 

 -0-72 



METEOROLOGICAL NOTES 

 Among the interesting papers which appear in the AnnaUsJu 

 Bureau Central Meteorologique de France iox 1 878 there is one 

 by Prof. Hildebrandsson, of peculiar value, On the Freezing 

 and Breaking-up of the Ice on the Lakes, the Epochs of Vegeta- 

 tion, and the Migration of Birds in Sweden, b.ased on the 

 observations made by a numerous staff of observers scattered 

 over the country. The paper is illustrated by a diagram showing 

 the seasonal distribution of temperature for ten of the more 

 typical climates of Sweden, and by twelve maps indicating 

 the geographical distribution of the physical and biological 

 phenomena under discussion. Since the lakes of Sweden, 

 which occupy a twelfth part of its entire superficies, exert 

 powerful and diverse influences on plant and animal life, 

 according as they are frozen or open, special attention 

 has been directed to their examination. The results show 

 that while the lakes in the extreme south are covered with ice 

 on an average of ninety days in the year, those in the extreme north 

 are 230 days bound w ith ice. The average date of the freez- 

 ing of the lakes in the north is October 10, whereas in the south 



this does not take place till December 10. On the other hand, 

 the ice breaks up in the southern lakes on April i, but in the 

 north not until the first week of June. The maps show the 

 decided manner in which the curves are deflected and modified 

 by such extensive sheets of water as are presented by Lakes 

 Wener, Wetter, and Maelar, by height above the sea, and by the 

 Atlantic in different seasons. During the freezing of the lakes 

 the south-west winds of the Atlantic attain a maximum force 

 and frequency, and under this influence the high lakes to \vest- 

 ward of the head of the Gulf of Bothnia do not freeze till 

 November 30, or six weeks later than the lakes in the same lati- 

 tude near Haparanda. On the contrary, at the time of the break- 

 ing-np of the ice in spring, easterly winds are prevalent, and the 

 ice on the lakes near 'the head of the Gulf of Bothnia breaks up 

 four weeks earlier than that of the more elevated lakes to west- 

 ward. An interesting examination is made of the dates of the 

 breaking-up of the ice on Lake Maelar at Westerns from 1712 to 

 1S71, and from a comparison of the averages of each of the 

 ten-year periods it is seen that the earliest was April 14 for the 

 decade 1722-31, and the latest. May 5, for 1802-11. Whilst 

 the results for these 160 years indicate considerable fluctua- 

 tions, they give no countenance to the idea that any per- 

 manent cliange has taken place in the climate of Sweden. 

 Three maps show the number of days in which the plants that 

 flow er in the extreme south in April, and those in Slay, come 

 .succes^lively into bloom, and the leafing of trees occurs at diffe- 

 rent places on advancing northward. As regards the plants 

 which come into bloom in the south in April, their time of 

 flowering is forty-five days later at the head of the Gulf of 

 Bothnia, ani si.xty days later in the elevated districts to westward, 

 but as regards the plants which bloom in the south in^May, 

 the times are only twenty-five and' thirty-five days. The 

 curves of the May flowers are closely coincident with the 

 curves representing the breaking-up of the ice of the lakes. 

 The time taken for the advance northward from the south 

 to the head of the Gulf of Bothnia is twenty-three days 

 for the [leafing of trees and the flowers, of May, whereas 

 the time taken by the April flowers is forty-three days. 

 The curves showing the times of arrival of four of the more 

 marked of the migratory birds differ much from each other. 

 The lark arrives in the south on March I, and in the north on 

 May I, and the arrangement of the curves of arrival closely 

 .agrees with the curves showing the breaking-up of the ice 

 of the lakes but a month earlier. As regards however the 

 wild goose, the cuckoo, and the woodcock, the curves showing 

 their arrival assume a different form, and point to an intimate 

 connection subsisting between the arrivals and the temperature 

 of the place at w hich they arrive. 



To mark the high value they set on carefully-made observa- 

 tions, the Council of the Scientific Association of France have 

 awarded medals to- Lieut. Pouvreau, serving on the line from 

 Havre to New York, Lieut. Benoit, of the Yang-Tse, plying 

 between Marseilles and Shanghai, and Captain Corenwinder, of 

 the Grenadier, Dunkirk, for the meteorological observations 

 made by them, these comprising, in addition to the usual obser- 

 vations, numerous and elaborate notes on whirlwinds and other 

 special phenomena. At the same time a medal was awarded to 

 M. Vidal, schoolmaster 'at Fraisse, Herault, for a peculiarly 

 interesting series of observations made by him during the past 

 fifteen years, regularly in winter as well as in summer, at a 

 height of 3,150 feet above the sea. M. Vidal h.as also, from 

 his wide and varied knowledge of the natm-al sciences, rendered 

 effective service to scientific men in their excursions into dhe 

 higher districts of that part of France. 



Prof. Fornioni has recently described to the Istituto Lom- 

 bardo {Rendiconti, vol. xiii. fasc. 3) a simple nefodoscope, or 

 instnmient for measuring the direction of motion of clouds 

 (the instrument of the 'kuid known as that of Braun being 

 thought expensive and inconvenient to use). It consists of a 

 flat compass case with pivoted needle, above which is fixed hori- 

 zontally a plane mirror occupying the whole of the case. On 

 the surface of the glass are drawn diagonal lines corresponding 

 to the rise of winds. The amalgam is removed in a narrow arc 

 extending from north to north-west, so that the end of the needle 

 may be seen for the purpose of orientation, and this transparent 

 arc is graduated. A rod with terminal eye, freely pivoted on 

 the edge of the case, completes the instrament. When the 

 direction of a given cloud is to be determined, the nefodoscope 

 is placed in a horizontal plane and properly oriented. The rod 



