Dec. 



1886] 



NA TURE 



119 



the photometric work den; with it. The " Harvard Photometry," 

 and the " UranonietriaOxoniensis" together will carry down to all 

 time the record of the present brightness of the stars. They will 

 be especially valuable as data for determining changes in stellar 

 brilliancy. 



During the past ten years the number of variable stars has 

 risen from about 100 to nearly 150 ; and our knowledge of their 

 periods and light-curves has been greatly improved. In America, 

 Chandler and Sawyer, of Boston, and Parkhurst, of this city, 

 have done especially faithful work. During the ten years we 

 have had two remarkable "temporary stars," as they are cal.ed 

 — first the one which, in November 1S76, in the constellation of 

 Cygnus, blazed up from the ninth magnitude to the second, and 

 then slowly faded back to its former brightness, but to a nebulous 

 condition, as shown by its spectrum ; then also the one which, 

 last autumn, appeared in the heart of the nebula of Andromeda 

 as of the sixth magnitude (where no star had ever been seen 

 before), slowly dwindled away, and is now beyond the reach of 

 any existing telescope. Perhaps, too, we ought to mention 

 another little ninth-magnitude star in Orion's club, which last 

 December rose to the sixth magnitude, and is now fading ; it 

 seems likely, however, from its spectrum, that this is only a new 

 variable of long period. 



As to star-spectra, a good deal of work has been done in their 

 investigation with the ordinary stellar spectroscopes by the 

 Greenwich Observatory, by Vogel at Potsdam, and by a number 

 of other observers, — work well deserving extended notice if tinre 

 permitted. But the application of photography to their study, 

 first by Henry Draper in this city, and by Huggins in England, 

 is the important new step. By the liberality of Mrs. Draper, 

 and as a memorial of her husband, his work is to be carried on 

 with the ne^v photographic instrument and method just introduced 

 by Prof. Pickering at Cambridge. He is able to obtain on a single 

 plate the spectra of all the stars down to the eighth magnitude 

 in the group of the Hyades, each spectrum showing under the 

 microscope the characteristic lines quite sufficiently for classifica- 

 tion. A difierent instnmient is also to be built with the Draper 

 Fund, which wdl give single star-spectra on a much larger scale 

 and in fuller detail. 



During the decade, the stellar parallax has been worked at 

 by a number of observers. Old results have been confirmed 

 or corrected, and the number of stars whose parallax is fairly 

 determined has been more than doubled. The work of Brunn )W 

 and Ball in Ireland, of Gill and Elkins at the Cape of Good 

 Hope, and of Hall, at Washington, deserves especi.al mention. 

 A new heliometer of seven inches aperture has been ordered 

 fpr the Cape Observatory, and when it is received, a vigorous 

 attack is planned by co-operation between that observatory 

 and that of Yale College, which possesses the only heliometer 

 in America. 



During the ten years, our knowledge of double stars has been 

 greatly extended ; several observers, and most eminent among 

 them Burnham, of Chicago, have spent much time as hunters 

 of these objects, and have bagged between one and two thousand 

 of them. Several others, especially Doberck in England, and 

 Flammarion in France, have devoted attention to the calculation 

 of the orbits of the binaries, so that we have now probably about 

 seventy-five fairly well defined. 



In the study of the nebulse, less has been done. Stephan at 

 Marseilles and Swift at Rochester have discovered many new ones, 

 mostly faint, and Dreyer, of Dublin, has published a supple- 

 mentary catalogue, which brings Sir J. Herschel's invaluable 

 catalogue pretty well down to date. The studies of Holden upon 

 the great Orion nebula and the so-called " trifid nebula " deserve 

 special mention, as securely e-tablishing the fact that these 

 objects are by no means changeless, even for so short a time as 

 twenty or thirty years ; also the discovery of a new nebula in the 

 Pleiades by means of photOfjraphy. 



Ohservatories. — During the ten years, a considerable number of 

 new observatories have been founded. • Abroad, we mention as 

 most important the observatories for astronomical physics at Pots- 

 dam, in Prussia, and at Meudon, in France, also the Bischoffsheim 

 Observatory at Nice and its succursal in Algiers. The great 

 observatory at Strasburg can hardly be said to have been founded 

 within the period indicated, but the new buildings and new 

 intruments and new efficiency date since 1S80. We ought not to 

 pass unnoticed the smaller observatory at Natal, in South Africa, 

 and the private establishments of von KonUoly at O-Gyalla, of 

 Gothard at Hereny (both in Hungary), and of the unpronounce- 

 able gentleman Jedrzejewicz at Plonsk, in Poland, and the 



observatory at Mount Etna, from which, however, we have 'no 

 results as yet. '-^ 



In the United States, we have the public observatories at 

 Madison, Wis., at Rochester, N.Y., and at the University 

 of Virginia, and the, as yet, unfinished Lick Observatory in 

 California : also a host of minor observatories connected with 

 institutions of learning, and mainly designed for purposes of 

 instruction ; such establishments have been founded within ten 

 years at Princeton, at Norlhfield, Minn., at South Hadley, Ms., 

 at Beloit, at Marietta, at Depauw, at Nashville, and at St. 

 Louis, also at Franklin and Marshall College, and at Doane 

 College, in Nebraska, at Columbia College, Ann Arbor, and 

 Madison, Wis., and at one or two other institutions which escape 

 me for the moment. Several others are also at this moment 

 in process of erection. Every one of them has a telescope 

 from six to thirteen inches aperture, with accessory apparatus 

 sufficient, in the hands of an astronomer, for useful scientific 

 work. 



Inslrumcnis. — A large number of new instruments of great 

 power have been constructed. We mention the great thirty- 

 inch refractor of Pulkowa, the twenty-six-inch of Charlottesville, 

 and the twenty-three inch at Princeton, for all which the lenses 

 were made by our own Clark. We add the great Vienna 

 twenty-seven-inch telescope by Grubb, and the twenty-nine-inch 

 object-glass by the Henrys, made for the Nice Observatory, but 

 not yet mounted ; also the nineteen-inch telescope at Strasburg 

 by Merz. Grubb has also at present a twenty-eight-inch object- 

 glass under way for the Greenwich Observatory, and Clark has 

 nearly completed the monstrous thii ty-six-inch lens for the Lick 

 Observatory. There never was a decade before when such an 

 advance in optical power has been made. 



Great reflectors have been scarce, the only ones of much im- 

 portance constructed during the time being the twenty-inch 

 instrument at Algiers, and Mr. Common's exquisite three-foot 

 telescope, which he has lately sold to Mr. Crossley in order to 

 make way for one of five feet diameter, now, I believe, under 

 construction. The old three-foot and six-foot instruments of 

 Lord Ro.^se have been improved in various ways, and are still 

 in use, — especially in work upon lunar heat. Among newly- 

 invented instruments, we mention the meridian-photometer of 

 Pickering, the wedge-photometer of Pritchard, the almucantar 

 of Chandler, the concave diffraction-grating of Rowland, and 

 the bolometer of Langley — all, but one, American. Repsold's 

 improvements in the micrometer, in the heliometer, and in the 

 mounting of equatorials should also be mentioned here. 



As to new astronomical methods, enough has been already said 

 about photometry and astronomical photography. It is plain 

 that we are entering upon a new era. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 

 The examination for the Sheridan Muspratt Chemical 

 Scholarship at University College, Liverpool, will begin on 

 December 9. The Scholarship is of the valueof 50/. per annum, 

 tenable for two years. Candidates should apply to the Registrar 

 before December 6. 



SOCIETIES AND ACADEMIES 

 Paris 

 Academy of Sciences, November 22. — M. Jurien de la 

 Graviere, President, in the chair. — On the life and v\ork ol 

 L. R. Tulasne, by M. Ed. Bornet. The paper contains a 

 somewhat detailed account of the labours of this eminent 

 botanist, who was born at Azay-Ie-Rideau (Indre-et-Loire) on 

 September 12, 1815, and died on December 2, 18S5. Ap- 

 pended is a list of the scientific publications of MM. Louis- 

 Rene and Charles Tulasne. — On annnoniaco-magnesian phos- 

 phate, by M. Berthelot. In continuation of his previous re- 

 searches on the colloidal and crystallised states of the earthy 

 phosphates, and especially of the phosphate of magnesia, the 

 author here studies the double ammoniaco-magnesian phos- 

 phate, determining the conditions of formation of this compound 

 in chemical analysis. — The Montgaudier Cave, by M. Albert 

 Gaudry. The author describes a visit he recently paid to this 

 cave, which is situated in the Charente district, and which has 

 revealed several objects of an artistic character, dating from the 

 close of the Quaternary epoch, when the large fauna of extinct 

 species had already mostly disappeared. But some remains. 



