1'i;()(;ki:ss ok astkonomv vou ism am» ixkl'. n/> 



in detail the work ol the Aiiicrican i>:ir(ics upon llic lr;iiisit of \ Cnus 

 in I<S>S2 — a lact uicatly to be ifjiiettcd. Tlie |»ul)lication of tlic work 

 ui)on the 1874 transit is only ])artly (•onii)lete(l and consideraWh' work 

 still remains to be done npon the reductions for 18SL*, tlioniili results 

 for the solar ])aralla\ and certain (elements of the orbit of X'eniis. which 

 are practically tinal, have been ])ublished. Some occuUations of stars 

 by the moon, telegra[)ic determinations of differences of lon^yitude, tidal 

 ol)servations, and pendulum experiments still remain to be reduced, 

 for which, however, no funds seem to be availabh'. 



Dr. Auwers' result* for the Geruuin heliometer measures of the 

 transit of \'enus in 1874 is a solar ])arallax of 8".877 ± 0".04;}, there 

 being- in all •■>()8 measures at four different stations; in 1881* four sta- 

 tions were occupied and 44(! measures were obtained, the resulting ])ar- 

 allax being 8".879± (K'.(>37. 



J)r. IJattermanu. of the Berlin Observatory, has deduced a vahu' of 

 the solar parallax from L'50 occultations of stars between A})rd, 1884, 

 and October, 1885, having by careful observation beeu able to utilize 

 the occultations of a consideiable number of faint stars near new moon. 

 The resulting solai' i)ara]lax is8".704± 0".0]0. 



The determination of the solar parallax by means of nu'ridian (►b- 

 servations of Mars at oi)])osition was attempted in 18()U, and again in 

 in 1877, but the results obtained were generally considered by astnm- 

 omers as too large, there being indications of a systematic error in the 

 observations of Mars, or of the comparison stars, or of both. A slight 

 nioditication of the previous methods of observation was suggested by 

 Prof. lOastnum, and a circular was issued by the V. S, Naval Observa- 

 tory re(iuesting' the coo|)eration of other observatories in tiie obsersa- 

 tion of Marsduiing the opposition in tin' suuunei- of I8i>L*. 



IM.A..\ETS. 



Mercury : Diameter of M<rriiri/.-—\ new determination of t he diam- 

 eter of Mercury has been made by Mr. And)ronn from lieiiomt^ter obsei- 

 vations at (icittingen. the mean result being (i"..")80, comparing lavor- 

 al)ly with the generally a<lopted \alue. 



Transit of Mercury, May l>, /n.'>/. — A tiansit of .Mercury over the sun's 

 disk took ]>lace on Ma\' !), 1801, the lirst since November" 7, 1881. The 

 ol)ser\ation of these transits no longer ]);)ssesses si)ecial importance, as 

 the determination of t he solar parallax, for which lliey aic t lieoretically 

 \aluable. can now be made more aecui-ately l)y other means. Ob- 

 ser\ations of the contacts Ix^tween the disks of the sun and planet are 

 useful in determinations of the i)laiu't's oibil and the i)hysical i)he 

 nomenaare soin<'times of interest. The transit on May it, 18!U. \\as only 



■ Asiidii. .\:i(iii-. :;(it;t;. 



