40 



ASTRONOMICAL PROGRESS AND PHENOMENA. 



and the boxes were made to fit the latter in 

 shape. These boxes were inclosed in two 

 others of steel, each nearly cubical, and packed 

 with hair. Each steel box was then inclosed 

 in another steel box, the inner sides of which 

 were covered with spiral springs, and both 

 boxes were made air-tight and water-tight and 

 placed in outer chests packed with asbestus to 

 render them fire-proof. They were then sus- 

 pended by pivots in strong wooden frames, 

 with means for turning one-quarter round 

 every day during the journey. This was in 

 order to prevent any molecular disarrangement 

 in the glasses, and to avoid the danger of polari- 

 zation, through the jarring of the train. The 

 great 75-foot dome is in place and works well. 

 It revolves with a longitudinal pressure of 225 

 pounds, so that the hydraulic machinery pro- 

 vided is almost unnecessary. Work upon the 

 mounting, which is still in the hands of Messrs. 

 "Warner and Swasey, is progressing favorably. 



The new observatory of Bucknell University, 

 Lewisburg, Pa., was finished early in 1887. 

 It is provided with a 10- inch Clark equatorial, 

 and a 3-inch transit instrument. Creighton 

 College, at Omaha, also has a new observatory, 

 with a 5-inch equatorial and a 3-inch transit. 

 An exchange of longitude-signals was made 

 with the Naval Observatory, Washington, in 

 August, 1887. 



The Solar Parallax. The report of the com- 

 mittee appointed to superintend the arrange- 

 ments for the British expeditions to observe the 

 transit of Venus in 18S2, together with the 

 report of Mr. Stone, who had charge of the 

 reductions, has recently been published as a 

 Treasury document. Expeditions were sent 

 from England to Jamaica, Barbadoes, Bermuda, 

 Cape of Good Hope, Madagascar, New Zealand, 

 anil Brisbane, Australia ; and the observers 

 were successful at all these stations except 

 Brisbane, where the sky was cloudy. The 

 British committee were not satisfied with their 

 photographic work in 1874, and for various 

 reasons they decided to rely entirely upon con- 

 tact observations in 1882. From the observa- 

 tions of external contact at ingress, Mr. Stone 

 has obtained a parallax of 8'760" 0-122" ; 

 from those of internal contact at ingress, 

 8-823" 0-023"; from those of internal con- 

 tact at egress, 8-855" 0-036"; and from those 

 of external contact at egress, 8-953" 0-048". 

 The most probable combined result he considers 

 to be 8-832" 0-024", which corresponds to a 

 mean distance of 92,560,000 250,000 miles 

 between the earth and the sun. 



The commissions of the United States and 

 France trusted principally to photography in 

 their schemes for observing the transit of 1882. 

 Of the negatives obtained under the auspices 

 of the United States Commission, after the re- 

 jection of all imperfect ones, there remained 

 1,571 which have been measured, and Prof. 

 Harkness believes that the value of the solar 

 parallax deducible from them will be obtained 

 early in 1888. The French Commission have 



measured 1,019 of their negatives, and in Feb- 

 ruary, 1887, M. Bouquet de la Grye announced 

 to the Academy of Sciences that the computa- 

 tions necessary for their reduction were half 

 finished, and would probably be completed 

 about the end of 1887. 



The German Commission trusted principally 

 to heliometers in the observations made under 

 their direction, and Dr. Auwers has recently 

 published a large volume containing investiga- 

 tions of the constants of the instruments em- 

 ployed ; but it is not known when the resulting 

 parallax will be obtained. 



The Sun. During 1886 sun-spots were con- 

 fined almost entirely to the southern hemi- 

 sphere of the sun, and there was a decided de- 

 crease in their size and number, relieved only 

 by outbursts in March and May. Faculse and 

 eruptions seemed to follow the spots. The 

 prominences diminished in height and mean 

 extent, but they were nearly equally divided 

 between the two solar hemispheres, and the 

 decrease was not so rapid as in the case of the 

 spots. The Greenwich photographs, supple- 

 mented by those from Dehra Dun in India, 

 show that for the thirty-eight days beginning 

 Oct. 31 and ending Dec. 7, 1886, there were 

 only seven days on which even a single spot 

 was shown. For a rotation and a half the sun 

 was practically free from spots. Riccd, on 

 searching the Palermo records, finds a similar 

 case in 1875, five years after the maximum of 

 1870, and nearly eight years after the mini- 

 mum of 1867. He predicts that the true mini- 

 mum of the eleven-year period will fall in 

 1890. Wolf's observations at Zurich show that 

 the variations in the spots and in magnetic phe- 

 nomena kept together in 1886 as in previous 

 years. 



An exhaustive discussion of the sun's hori- 

 zontal and vertical diameters, with special ref- 

 erence to the alleged variations in its mean 

 annual diameter following the period of the sun- 

 spot cycle, has been made by Dr. Auwers from 

 the Greenwich, Washington, Oxford, and Neuf- 

 chatel meridian observations. He concludes 

 that there is no valid reason for supposing the 

 sun's diameter to vary, and that the apparent 

 changes arise from insufficiently determined 

 personal equations. He also points out that 

 meridian observations are quite unsnited for 

 determination of any possible ellipticity in the 

 sun's disk, and that there is no reason to con- 

 clude from these results that such ellipticity 

 exists. The several mean values of the sun's 

 (assumed circular) diameter are: Greenwich, 

 32' 02-37"; Washington, 32' 02-51"; Oxford, 

 32' 02-19"; Neufchatel, 32' 03'27", the discord- 

 ances of which are to be ascribed to instru- 

 mental or uneliminated personal peculiarities. 

 In a second paper, Dr. Auwers discusses the 

 apparent, changes of both the horizontal and 

 vertical diameter during the course of a year 

 deduced from meridian observations, and he 

 concludes that the periodic variations in the 

 monthly value of the diameters result not from 



