270 



NATURE 



{y^ly 17, 1879 



planetary nebula H. IV. 37, the position of which is in 

 R.A. i7h. s8m. 36s., N.P.D. 23° 2i'-8 for 1880. The 

 nebula appears in the South-refractor as a somewhat 

 elliptical disk, whose major axis is about half a minute, 

 and has in the centre a well-defined point resembling a 

 star of the eleventh magnitude. This point was com- 

 pared in declination with a star to the north of the tenth 

 magnitude, preceding the nebula by 2Ss., the same method 

 of observing being used that had been adopted in Dr. 

 Brunnow's earlier researches on stellar parallax. The 

 observations extend over thirty-three nights, from 1871, 

 August 13, to 1872, August 6, and their discussion gives 

 for the parallax of the nebula, + o"-o47 ± o"-03o. Prof. 

 Bredichin, in "Annales de 1' Observatoire de Moscou," 

 vol. iii., has found a negative parallax (- o"-o64 ± o"-o39), 

 using also the method of differences of declination with 

 the same star of comparison. The results of these 

 investigations may be taken to indicate that the parallax 

 of this planetary nebula if measurable at all must be very 

 small The second paper contains Dr. Ball's observations 

 of 61 Cygni, and his determination of its parallax there- 

 from. By what was at first an inadvertence, instead of 

 using the following of the two components as Dr. 

 Brunnow had done, the preceding one was observed, and 

 the mistake not being remarked until the series was con- 

 siderably advanced, it was resolved to complete it as 

 begun; perhaps the result possesses for this reason 

 additional interest. Dr. Ball finds for the parallax 

 -f o"'4654 ± o"-o497, which is about a mean of the 

 values obtained by Bessel, Johnson, Peters, Struve, and 

 Auwers, which appear entitled to the greatest weight. 

 The observations extending from 1877, July 3, to 1878, 

 June I, are given in their original form. The third 

 paper, also by Dr. Ball, relates to " observations in search 

 of stars with a large annual parallax," forty-two stars 

 being examined for this purpose, including several red 

 and variable stars : the results, however, are found to be 

 entirely negative as regards the object in view, no amount 

 of parallax worth following up being suggested. The 

 principle upon which the observations were made is fully 

 described and their details appended to the memoir. The 

 last portion of the Dunsink publication contains Dr. 

 Brunnow's measures of double-stars 1870-73. 



The Solar Eclipse of July 19.— The Observatory 

 of Paris is situate very close upon the northern line of 

 simple contact in this eclipse, which will add interest to 

 observations that may be made there. The Connaissance 

 des Temps employing the lunar tables of Hansen and the 

 solar tables of Leverrier, gives the magnitude of the 

 eclipse only 0-013 (the sun's diameter being taken as 

 unity), commencement at 7h. 461m. a.m. mean time at 

 Paris, ending at 8h. 5-4m. At Gibraltar the magnitude 

 of the eclipse will be 0-32 at 7h. 9m. local mean time, and 

 at Malta 0-38 at 8h. 4.6m. As we have before remarked 

 the only civilised station where a great eclipse is likely to 

 be witnessed is Aden. The eclipse is strictly an annular 

 one, but the moon's augmented semi-diameter is only five 

 seconds less than the sun's semi-diameter, where the 

 greatest phase occurs near apparent noon. At Aden at 

 oh. 12m. P.M. 97-iooths of the sun's diameter will be 

 covered by the moon ; the line of annular eclipse falls 

 upon the opposite African coast. 



Periodical Comets in 1880.— Two known comets of 

 short period will be observable before the end of the 

 ensuing year, viz., Winnecke's, which may be in peri- 

 helion early in December, and Faye's, which, according 

 to Dr. Axel-Mdller, again arrives at its least distance 

 from the sun in January, 1881. The perturbations of 

 Winnecke's comet during the actual revolution will not 

 be important, and from Prof. Oppolzer's elements of 1875 

 it seems likely that difficulty may be experienced in 

 securing observations, the track in the heavens if we 

 assume the time of perihelion passage to be December i'5 

 being as follows : — 



METEOROLOGICAL NOTES 



The Eleventh Contribution to Meteorology by Prof. 

 Loomis appears in the American Journal of Science and 

 Arts for this month. With the view of inquiring whether 

 areas of low atmospheric pressure sometimes result from 

 a circulation of the surface winds not extending to a 

 height of 6,000 feet. Prof. Loomis has examined eighty- 

 nine storms and compared in each case the average 

 direction and force of the surface winds near the base of 

 Mount Washington with the winds at the top of the 

 mountain. In the majority of those cases in which a 

 storm with its area of low barometer passes over the New 

 England States, the usual system of circulating winds 

 which prevails at the surface, does not extend to the 

 height of 6,000 feet. In cases, however, when the de- 

 pression is unusually great, this system of circulating 

 winds extends to that height. When the system of circu- 

 lating winds reaches to the top of Mount Washington, 

 the change of wind into the east usually begins near the 

 base eleven hours sooner than on the top of the moun- 

 tain ; and the change subsequently into the west 

 usually begins at the base five hours sooner than on 

 the top. 



In the same paper Prof. Loomis examines eight storms, 

 the average courses of which were approximately from 

 south to north, and six storms which travelled from north 

 to south, with the view of obtaining information from 

 such abnormal storm paths, regarding the causes which 

 determine the movement of storms with their low baro- 

 meters from place to place. These two groups of storms 

 present characteristics very different from each other. 

 As contrasted with the other group, storms moving to 

 northward show a central pressure, becoming more de- 

 pressed as they advance ; the southerly winds accompany- 

 ing them are marked by a greater humidity and velocity; 

 and the rainfall is very greatly in excess. If attention be 

 exclusively directed to storms moving to northward the 

 facts seem to favour the idea that in a great storm the 

 condensation of vapour is an efficient cause which controls 

 the movement of the winds. Storms moving to south- 

 ward, however, show very different results, areas of low 

 pressure being observed to be formed with little rain and 

 sometimes even with none at all. The general conclusion 

 the inquiry seems to point to is that the initial depression 

 of the barometer is the result of a system of circulating 

 winds, the most frequent cause of which is two or more 

 areas of high pressure at considerable distances, often 

 1,400 miles from each other, differences of temperature 

 and humidity being important agents in producing, but 

 more especially in maintaining, such a system of winds. 

 If this be so, then the points in the inquiry calling for the 

 most serious attention are the causes which conspire in 

 bringing about those wide areas of high pressure round a 

 region of lower though still high pressure and the concen- 

 tration of moister and warmer air over this region. 



The Results of the Meteorological and Magnetic Obser- 

 vations for \Z-j'& made at Stony hurst College have just 

 appeared. To the routine work of the observatory has 

 been added the preparation of an agricultural report sent 

 weekly to the Meteorological Office ; and to the usual 

 observations are added observations of crops, flowers, 

 shrubs, and trees, and a complete and very valuable table 



