2o6 



Nj^ TURE 



[July i, 1897 



Dines' anemometer, confirming the results of other observers 

 that the factor 3 (the ratio of the speed of the wind to that of 

 the cups) is too great. (2) The Director is able to report a 

 clean bill of health in his little colony (numbering altogether 

 about ICX) persons, including servants and their families) during 

 the plague epidemic. This satisfactory state is attributed to 

 additional ventilation, by removal of tiles, &c., to fumigation 

 twice a week by carbolic acid, to inoculation of every man, 

 woman, and child with Dr. Hafifkine's prophylactic serum, and 

 to the daily inspection of the quarters and inmates. 



The additions to the Zoological Society's Gardens during the 

 past week include a Ser valine Cat {Felts servalina) from East 

 Africa, presented by the Rev. Ernest Millar ; a Vulpine 

 Phalanger ( Trichosurus vulpecula) from Australia, presented by 

 Mr. M. A. Murray; a Common Squirrel (Sciurus vulgaris), 

 British, presented by Lady Acland Hood ; two Bateleur Eagles 

 (Helotarstts ecauda/us), two Common Herons (Ardea cinerea) 

 from East Africa, presented by Mr. Chas. Palmer ; a Red- 

 crested Cardinal {Paroaria cticuUata) from South America, 

 presented by Miss Edith M. Kenyon Welch ; a Grey Monitor 

 {Varantcs griseus) ixora Y.gy^i, presented by Dixon Bey; two 

 Natal Pythons {Python sebcc, var.) from Natal, presented by the 

 Hon. R. Carnegie ; an Orang-outang (Siiitia satyrus, 6 ) from 

 Sumatra, deposited ; two King Penguins {Aptenodyles pennanti) 

 from the Antarctic Seas, purchased ; a Burchell's Zebra {Eqinis 

 burchelli,<i), a Japanese Deer (Cervus sika,<i), two Glossy 

 Ibises {Plegadis fitlcinellus), bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Personal Equations in Transit Observations.— In 

 the reduction of transit observations the question of personal 

 equation is an important factor in the accuracy of the final star 

 places, and it is on this account that investigations are always 

 being pursued to determine the values of these equations for 

 each meridian observer. A communication of importance in 

 this respect appears in the Monthly Notices for May, by Prof. 

 Truman Saffbrd, who treats of the various forms of personal 

 equation in transit observations which arise from the non- 

 observance of the exact time of transit due to personality, 

 magnitude of the star observed, and the apparent velocity and 

 direction of movement. In his investigation Prof. Safi"ord con- 

 cludes that since the year 1795 most eye and ear observers 

 anticipate the true time of transits, taking the average observed 

 as a standard. At Greenwich, since 1885, the great majority of 

 observers by the eye and ear method anticipate the time of their 

 own chronographic transits, while the average chronographic 

 observer registers transits after the time of their occurrence by 

 an amount not greatly different from that which is required to 

 register an impression on the senses. The personal error arising 

 from the rate of movement of the star, or as it is termed the 

 polar equation, amounts sometimes to a very considerable 

 quantity, and several values are given in the paper showing the 

 importance of a strict elimination of this variable. Dealing with 

 faint stars an observer using the chronographic method registers 

 its time of transit later than that when a more bright one is 

 taken, while with the eye and ear method the time of transit is 

 generally somewhat earlier. The change in direction of motion 

 of stars due to their being observed sometimes north and some- 

 times south of the zenith, gives rise to a further personal equation 

 discovered by Dr. Gill, but which is found generally very small. 

 The investigation shows that the general theory thrown out by 

 Bessel is thus confirmed, and Prof. Safibrd points out that the 

 same is true with regard to Wundt's explanation of the eye and 

 ear process from a psychological point of view. 



Paris Observatory Report.— In his annual report for the 

 year 1896, M. Lcewy, after a brief reference to the loss the 

 observatory sustained in the death of M. Tisserand, sums up 

 the work of the past twelve months. Among some of the chief 

 points to which reference is made, may be mentioned the two 

 astronomical congresses that have been held at the Observatory, 

 and the work connected with the great enterprise of the photo- 

 graphic chart of the heavens. Many of the difficulties connected 



NO. 1444, VOL. 56] 



with the latter have for the great part been overcome, biit there 

 still remain one or two important questions which have been 

 left over for another meeting. M. Bigourdan's work on the 

 determination of the accurate position of the nebulse between 

 declination 90° and - 30° has made great progress, and it is 

 expected that it will take him three years more to complete the 

 whole region under survey. The work on the photographic 

 atlas on the moon has been successfully continued, and besides 

 the issue of the first portion of the atlas during the past year, a 

 second one will be published in the present one. The report 

 further gives a brief account of M. Deslandres' work on the 

 motions of stars in the line of sight, and the results of the 

 expedition to Japan to observe the solar eclipse of August last. 

 The work done in other departments of the observatory during 

 last year, such as the Bureau des Calculs, Service Meridien, &c., 

 is also briefly described. 



Belgian Time-Reckoning. — Since the beginning of May, 

 the hours in Belgium have been reckoned from o to 24, noon 

 being represented by 12, and midnight by o or 24, according to 

 circumstances. In the case of a train starting exactly at mid- 

 night, it is said to leave at o hour ; and one arriving exactly at 

 midnight is considered due at 24 hours, or, as we should say, at 

 24 o'clock. We learn from the [oitrnal of the Society of Arts 

 that on the time-tables the times between midnight and i a.m. 

 are indicated by a zero, followed by a point and the letter H, 

 the latter followed in turn by the number of minutes. The 

 dials of existing clocks at railway stations are completed by the 

 figures 13, 14, 15, &c., to 24, added below the existing figures 

 of I, 2, 3, &c. , to 12. This change, which should have come 

 into force with the new year, was deferred for three months, on 

 account of the administrative difficulties which it involved, and 

 also in the hope that the Greenwich meridian, now adopted in 

 Belgium, might also be accepted by France at the same time, 

 urgency having been voted for a measure to that effect by the 

 Chamber of Deputies. 



A NEW CLASSIFICATION OF STELLAR 

 SPECTRA} 

 IV/TANY of the recent advances in our knowledge of the con- 

 •'■■'■ stitution of the stars are traceable to Prof. Pickering's 

 revival of Fraunhofer's mode of investigating stellar spectra. 

 The endowment of this research by Mrs. Draper as a memorial 

 to her husband. Dr. Henry Draper, has enabled Prof. Pickering 

 to apply this method in two principal directions. First, a series 

 of photographs was taken on a small scale to indicate the chief 

 characteristics of the spectra of a very great number of stars ; 

 second, in the case of the brighter stars, another series was taken 

 with greater dispersion with the view of facilitating an inquiry 

 into the more minute features of each type of spectrum. The 

 results of the first investigation are comprised in the well-known 

 "Draper Catalogue," giving particulars of the spectra of ovet 

 10,000 stars (Nature, vol. xlv. p. 427), and the research has now 

 been advanced another stage by the publication of the results 

 obtained along the second line of inquiry. 



The new series of photographs has been taken with one to 

 four objective prisms of 15" each in conjunction with the ii-inch 

 Draper telescope of 153 inches focal length. 



When four prisms were employed, the spectra were 8 centi- 

 metres long from H^ to H, , and with one prism 2 centimetres. 

 Since only the brighter spectra could be photographed with the 

 highest dispersion, some of the more typical of these were also 

 photographed with one and two prisms in order to give a proper 

 term of comparison with the spectra of the fainter stars. In all, 

 4800 photographs of the spectra of 681 of the brighter stars 

 north of declination - 30° are included in the present discussion. 

 By the use of plates stained with erythrosin the spectra of 

 several stars have been photographed in the green and yellow. 



As in all previous work involving considerable numbers of 

 stellar spectra, it has been found that the spectra can be classified 

 in large groups, between which there are intermediate varieties. 

 "Large numbers of almost identical spectra are found, even 

 when several hundred lines appear in each." The description 

 of the spectra accordingly takes the form of an account of 

 typical stars in the scheme of classification adopted, accompanied 

 by tables of the lines which characterise the larger groups. No 



1 Spectra of bright stars, photographed with the ii-inch Draper telescope 

 as a part of the Henry Draper Memorial, and discussed by Antonia C. 

 Maury, under the direction of Edward C. Pickering. (Annals of Hatvard 

 College Observatory, vol. xxviii. part i, 1897.) 



