October 31, 1907] 



NA TURE 



667 



queathed to him by former astronomers. One of 

 these was the great Paris catalogue of stars, depend- 

 ing upon meridian observations made within the 

 period 1837-1881, including the re-observation of all 

 Lalande's stars. The complete work, published in 

 four sections, furnishes the places of nearly 35,000 

 stars, based upon 387,000 single measures. This 

 heavy piece of work was brought to a very satisfac- 

 tory conclusion under the supervision of M. Loewy, 

 and by its completion the observatory staff is relieved 

 of an oppressive incubus. The other is the Inter- 

 national Star Chart, which had its origin under 

 Admiral Mouchez. Not only has this work been 

 prosecuted with ardour at the observatory, but en- 

 couragement and assistance were given to all who 

 participated in the scheme, by means of conferences 

 that have been held from time to time in the obser- 

 vatory at the suggestion of the regretted director. To 

 both these projects M. Loewy gave as generous and 

 consistent support as though he were responsible for 

 their introduction. 



M. Loewv's more immediate influence on the con- 

 duct of the observatory is shown in the steady prose- 

 cution of another piece of work, the chart of the moon 

 derived from photographs taken with the equatorial 

 coud6, a form of telescopic mounting with which 

 AI. Loewy's name is closely connected. The long 

 focal length, which is one of the advantages secured 

 in this class of telescope, giving an image of the moon 

 more than sev-en inches in diameter, made this instru- 

 ment peculiarly suitable for the investigation. The 

 admirable reproductions made from the negatives 

 justify the time and attention that have been bestowed 

 on the enlargements. Concurrently with the issue of 

 the maps there have been published acute dissertations 

 on the phvsical constitution of the moon, founded on a 

 minute critical studv of the lunar surface. This close 

 and detailed examination led the director to conclude 

 that there were evidences of a permanent elongation 

 of the moon's figure towards the earth, and of a sur- 

 face action tending to diminish the angular velocity 

 of rotation. 



But besides the study of the moon's surface, the 

 equatorial coude has served another purpose. The 

 principle of construction is so well known that it is 

 not necessary to describe it here. But in designing 

 this instrument M. Loewy had in view the possibility 

 of obtaining greater stability than is attainable with 

 ordinary equatorial^, and by taking advantage of this 

 stabilitv to measure large angular distances on the 

 celestial sphere. Having determined, by a thorough 

 examination of the theory, the sources of error 

 inherent in the instrument, M. Loewy proceeded to 

 use it for obtaining a new value of the constant of 

 aberration by an entirely novel method. For this pur- 

 pose he placed a double mirror, formed by silvering 

 two faces of a large prism of glass, in front of the 

 object glass. The double mirror was capable of rota- 

 tion about the axes of the telescope, so that by reflec- 

 tion from the two silver surfaces the images of two 

 stars in different parts of the sky could be brought 

 into the field side by side, and the distance between 

 them measured in the common plane of reflection. By 

 choosing suitable stars and making the necessary 

 measures six months apart, the quantity measured 

 could be made four times that of the constant of 

 aberration. For greater accuracy the stars selected 

 had the same altitude so -s to reduce the effects of 

 refraction to a minimum hut by changing the plan 

 of observation it was possible to investigate the effects 

 of refraction separately. The instrument lent itself 

 to methods of great beauty and ingenuity, displaying 

 both the mechanical ability of the inventor and the 

 varied resources of the mathematician and astronomer. 

 The Royal Astronomical Society fittingly acknow- 



NO. 1983, VOL. 76] 



ledged its appreciation of the important services M. 

 Loewy had rendered to astronomy by awarding him 

 the gold medal. Needless to say, he was an 

 honorary member of that society as of many others, 

 both in his own country and abroad. 



It would not be possible, even if it were desirable, 

 to record all the varied occupations in which M. 

 Loewy was engaged in the course of his scientific 

 career. His position made him frequently the adviser 

 of his Government in many important matters. His 

 services to the Bureau des Longitudes, in his capacity 

 of director of the Connaissance des Temps, will be 

 readily acknowledged. The part he played in various 

 conferences, such as those which arranged the scheme 

 for observing the planet Eros and for securing 

 uniformity in the employment of astronomical con- 

 stants, has been already mentioned. We can only 

 deplore, in company with the whole guild of science 

 throughout the world, the loss of one who ornamented 

 a dignified position and worthily supported the tradi- 

 tions of the National Observatory. Within the last 

 few vears the continuitv of its direction has been too 

 frequentlv interrupted by the loss of its distinguisKed 

 chiefs, .\mong these brilliant memories the name of 

 Maurice Loewy will hold an honoured place. Round 

 his grave in respectful sympathy were grouped the 

 representatives of many learned societies. In addi- 

 tion to those of France, there were present members 

 of the .Academy of Sciences of Vienna, of the R. 

 -Accademia dei Lincei, while the Royal Society 

 of London, as well as the Royal .Astronomical Society 

 and the British .Association, were represented by Sir 

 David Gill and Major MacMahon. 



NOTES. 



It is reported that at Monday's meeiinj; of the Paris 

 .Academy of Sciences Prof. Lapparent described some 

 experiments by Prof. Bordas upon the conversion of 

 corundum into precious stones by the influence of radium. 

 It is stated that when fragments of corundum were placed 

 in contact with a tube containing radium for a month 

 they changed colour entirely, and were transformed into 

 crystalline varieties of the mineral, some pieces becoming 

 yellow, like topaz ; others purple, like amethyst ; blue, as 

 sapphire ; and red, as rubies. The gems thus produced 

 were submitted to a jeweller, who was unable to dis- 

 tinguish them from precious stones. We shall await with 

 interest the appearance of the Comptes rendus of Monday's 

 meeting for particulars of these experiments and results. 



The death is announced of Prof. Gustav Adolf Zeuner, 

 the distinguished authority on applied mechanics. Born 

 at Chemnitz in 1828, he was the founder, and editor from 

 1853 to 1857, of the German journal the Zivilingenieur. 

 In 1855 he was appointed professor at the Zurich Poly- 

 technic, of which institution he was director from 1865 

 to 1868. From 1871 to 1875 he was director of the Frei- 

 berg School of Mines, and from 1873 to 1890 he was also 

 director of the Dresden Polytechnic. He retired in 1895. 

 His works included treatises on valve gearing and on the 

 mechanical theory of heat. 



Dr. Elis Stromgren, private tutor at the Kiel Uni- 

 versity, has been appointed professor and director of the 

 Copenhagen Observatory in succession to Prof. T. N. 

 Thiele, retired. 



Sir Herbert M.^xwell has been appointed chairman of 

 the council of the National Association for the Prevention 

 of Consumption in succession to the late Sir William 

 Broadbent, and Dr. C. Theodore Williams has been elected 

 vice-chairman. 



