December 15, 1898] 



NA TURE 



159 



Following upon this communication, I'rof. I'orro gave an 

 account of the present state of the calculations being made at 

 New York and Turin for a new reduction of the observations of 

 Piazzi, and for the compilation of a stellar catalogue founded on 

 the same. According to arrangements made between Dr. 

 Auwers and Prof. Schiaparelli, the work is divided between 

 Dr. Herman S. Davis, of the Columbia University Observatory, 

 and Prof. Porro. Mrs. Coreita R. Davis shares in it at New 

 York, Dr. Vittorio Balbi at Turin. 



A third notice given by Prof. Porro concerns the eighteen 

 tables, in which he has had reproduced in facsimile the original 

 sketches of the constellations, drawn by Francesco Bianchini in 

 the seventeenth century. 



The sketches contain the first essays on exact relative ocular 

 determinations of the stellar magnitudes, executed by a method 

 not differing essentially from that suggested and applied a century 

 and a half later by Herschel. Argelander and Schiaparelli had 

 deplored the loss of these papers, which ought to be of service 

 for the historical study of the variable stars. The speaker had 

 been able to find the manuscripts in a code of the Capitular 

 Library of Verona, to which Bianchini, when dying, had be- 

 queathed all his books ; and had found that, without giving to 

 the afore-named study the contribution expected by Bianchini 

 and Montanari (of which also observations are reported), the 

 papers themselves furnish the first document of exact determin- 

 ation of the relative magnitudes of the stars, which is recorded 

 in the history of astronomy, resolving the query propounded by 

 Argelander in his paper, " De Fide Ur.anometriae Bayeri." 



Dr. Fritz Cohn, of Konigsberg, described some general re- 

 sults of a new reduction of the most ancient meridian observ- 

 ations of Bessel. Of the observations made by Bessel in the 

 years 1S14-19, none had been'published till now, save the known 

 Fundamental Regiomontan Catalogue of Maskelyne's thirty-six 

 stars for the epoch 1815. Bearing in mind the date of the 

 observations and the name of the observer, it had been thought 

 desirable to undertake a reduction of the materials gathereil 

 together. As the fundamental problem it seemed necessary to 

 show the systematic errors of the Besselian method, and 

 eliminate the damaging effect. Inasmuch as the presentation 

 of the systematic errors in Bessel's catalogue depends con- 

 siderably on the method of reduction adopted, it was needful to 

 seek for a method that should limit as much as possible the in- 

 fluence of the systematic errors on the results. Applying a 

 method studied purposely to such an end, a considerable im- 

 provement of Bessel's catalogue was obtained. But a perfectly 

 satisfactory result could not be obtained till the cause of the error 

 was discovered in a different distribution of the passages of the 

 stars between day and night, and until such cause could be 

 exactly calculated. After such a result it would be desirable 

 that also in other series of observations of fundamental stars, 

 especially andent ones, search should be made of eventual 

 systematic errors, because it is to be expected that from the 

 consideration of these the accuracy of the results would gain 

 considerably. 



Prof. Foerster read a brief notice on some questions con- 

 nected with the length of the year and the calendar. The 

 numerous numerical data on which his discourse was founded 

 do not lend themselves to a recapitulation of the interesting 

 matter treated with the usual ability by the illustrious director 

 of the Berlin Observatory. 



On the measurement of the brightness of the nebulae and 

 the clusters of stars, spoke Dr. Holetschek, of Vienna. He 

 hasbeeii occupied for several years in determining the luminous 

 impressiori made by the light of a comet through the weakest 

 telescope in which the comet itself is visible, and eventually by 

 the naked eye, noting the stars that are visible with equal 

 facility or with equal difficulty in the same conditions. In this 

 manner it has been possible for him to represent such luminosity 

 with numbers, and now he has begun the application of the same 

 system to nebulae and clusters of stars also. Manifestly, the 

 method does not lend itself equally well to all classes of similar 

 celestial objects : in particular it is not adapted for nebulae 

 jllummated diffusely and uniformly, and for clusters of stars 

 spreading over a wide space, as those in the Classes VII. and 

 VIII. of Herschel- 



Applying his method to objects of the first two classes of 

 Herschel, Holetschek has found, for instance, that the bright- 

 ness of the Pleiades corresponds to magnitude 1-5, that of the 

 Presepe of Cancer to 4, of the nebulae of Andromeda to 5-3. 



NO. 1520, VOL. 59] 



Messier having compared the brightness of the comet 1779 to 

 that of four different nebulae, of brightness 6'5 ; 7 ; S7 ; and 

 9'6, the author has been able to extract good values for the 

 brightness of the comet. In the determinations executed between 

 1SS6 and nosv, he did not succeed in recognising any variations 

 in the brightness of the nebulae under observation. 



Prof. R. von Kiivesligethy, of Budapest University, referred 

 under the title " Ueber die Beiden ParSmetergleichungen der 

 Spectral Analyse," on the studies just finished by him in the 

 field of spectral analysis, the scope of which is to found astro- 

 physics on mathematical bases. He shows how the two funda- 

 mental equations of the theory of heat are destined to have the 

 same importance in astrophysics as the principles of mechanics 

 have in astronomy, and that it is only now necessary to deter- 

 mine by observation the quantities that figure in such equations, 

 To such an end the equation of emission is formed very simply 

 in function of the length of the wave, and of two parameters 

 that depend on the nature of the bodies ; and it is not difficult 

 to prove that the proceeding is severe, recurring to the proposi- 

 tion ofClausius on the radiation and to the equations of dis- 

 persion. Besides, it represents perfectly a series of bolometrical 

 measures of the spectrum. The author insisted on the application 

 of his theory to very important questions, also of mathematical 

 astronomy, as the determinations of the parallaxes, the volume 

 and densities of the heavenly bodies. 



Father Fenyi, S.J., spoke on the observations of solar pro- 

 tuberances at the Kalocsa Observatory from 1S84. He noted, 

 first of all, that the greatest heights of the protuberances observed 

 evidently depended upon the greatest amount of solar activity. 

 With regard to the nature of the protuberances, he observed 

 that they appear in the absolute vacuum, according to the 

 theory of Schmidt, by which the density of the critical stratum 

 around the sun could be determined with accuracy ; but hydrogen 

 cannot have a greater density than that of the critical stralimi, 

 and hence the maximum of density possible to hydrogen at 

 every height can be determined. If this density be determined 

 only for a height of 25", it is seen directly that no trace of 

 hydrogen can exist there ; because on a volume equal to that of 

 the sun a single molecule alone would fly from it. The theories 

 that contradict this result are, therefore, to be rejected. 



Prof Hartwig, of Bamberg, called attention to the star 

 SS Cygni, which, together with U Geminorum alone, forms a 

 special class of variables, that offers special occasions, by its 

 connection with new or temporary stars, to the study of these 

 mysterious stellar bodies. The character of this class consists 

 of an unexpected lighting up, followed by a rapid increase of 

 magnitude, after which comes a slow return to the usual bright- 

 ness. The spectographic study of SS Cygni seems possible for 

 the large instruments now in activity, and would certainly 

 furnish useful information on the causes of similar mysterious 

 phenomena. 



Another communication was made to the Congress by Prof. 

 Kreutz, who referred to the actual state of the calculations of 

 cometary orbits. 



.^mong the numerous vi.sits made by the members of the 

 Congress to noteworthy places in the city and in the kingdom 

 of Hungary, special mention should be made of the O Gyalla 

 Observatory, where the splendid hospitality of Dr. von Konkoly 

 was not less admired than his munificence in preparing and 

 presenting to the State a magnificent collection of instruments, 

 designed by him and constructed under his direction, and of the 

 Institute of Physics of the Budapest University, where they 

 attended the experiments on gravitation of Baron Ebtvos. The 

 general impression that remained was of sincere admiration for 

 the very notable progress made in the field of science by the 

 country of Hungary, whose name was given to a new planet dis- 

 covered by Wolf. Francesco Porro. 



RECENT PROGRESS IN ORNITHOLOGY."- 

 A S the editors of The Ibis have already remarked in their 

 preface to the volume for the present year, one of the 

 leading ornithological events of 1898 is the completion of the 

 " Catalogue of Birds." The twenty-sixth volume of this work, 

 prepared by Dr. Bowdler Sharpe and Mr. Ogilvie Grant, the 

 only one required to finish the series, will, I am assured, be 



1 Address given by Mr, Sclaterat the opening meeting of the British 

 Ornithologists Club, on October 19. 



