494 



NATURE 



[Februarys, 191 2 



OVR ASTRONOMICAL COLUMN. 



Dorni.iNc. of Martian " Canals." — Telcfjraphing to the 

 Aslronomischr Nachrichten (No. 4551) on January 25, Prof. 

 Lowell states that the canals (ianjjes 'n.) I ..nima are 

 <l()ublin);, both from the western mouth. 



Reportrd Fall of an Aerolite. — A .>.!...»., accident 

 is reported in a Lloyd'.s messajje from the Finisterre 

 /.Spain) .Sijjnal Station. The message states that at 

 I a.m. on January 25 the semaphore and telegraphic 

 .ipparatus was completely destroyed by the fall of a meteor, 

 thus causint; m im. rruption of both the maritime and land 

 communic.iii >ii- Ndihing, more than is implied in the 

 above messa^ie, i> reported as to the finding of any 

 meteorite or its fragments. 



.\ Bright Meteor. — From Tarn6w Prof. Anton Wilk 

 n ports the apparition, in a clear, cloudless sky, of a 

 bright meteor on November 15, 191 1. The path lay 

 between 2oh. 20m., +40°, and 22h. 40m., +30°, and was 

 traversed very rapidly. At the beginning of the flight the 

 meteor was about twice as bright as Venus, whilst during 

 the flight it gave off luminous particles, and was followed 

 by a long luminous trail. At first the colour was bluish, 

 then a glowing yellowish-white, and the duration of the 

 whole phenomenon was about three seconds. 



Fpiiemeris for Sciiaumasse's Comet, 191 i/j. — Astro- 

 nomische Nachrtchten No. 4549 contains an ephemeris for 

 «omet 191 i/i, computed by M. Schaumasse from the elliptic 

 elements now published by M. Fayet in the same journal. 



The present approximate position is i6h. 19m., —3° 57', 

 and the comet is only about one-sixth as bright as when 

 -discovered. 



M. Fayet directs attention to the similarity of the orbits 

 of this comet and that of 1894 I. (Denning). 



Observations of Comets. — Bulletin No. 3 of the 

 Khedivial Observatory, Helwan, contains a further list of 

 -positions of Halley's comet determined from photographs 

 taken with the Reynold's reflector by Mr. Knox-Shaw. It 

 lias been found desirable to apply a temperature term in 

 the reduction of the measures, the temperature having 

 varied between 6° and 24° C. 



Numerous observations of comets are recorded in Nos. 

 4550-1 of the Astronomische Nachrichten from several 

 observatories. 



Distances of Spiral Nebulae. — Assuming that the spiral 

 nebulae are external galactic systems, Prof. Max Wolf 

 makes some speculations as to their relative distances in 

 No. 4549 of the Astronomische Nachrichten. His deduc- 

 tions are based also on the assumption that such systems 

 are of the same order of actual magnitude, hence the 

 apparent diameters are inverse measures of their distances. 



Measures of eight objects have been made, and the 

 relative distances derived, both from the measures of the 

 length and the breadth ; the results for each object agree 

 fairly well. Taking the parallax of certain objects in the 

 Milky Way, e.g. Nova Persei, as ooi", gives a means of 

 calibrating the relative scale, and Prof. Wolf's final 

 speculative numbers are as follow : — 



Quj^, Distance in Apparent diameter, Diameter in 



■' light years , light years 



M3I ... 33,000 ... I20 IIOO 



M33 94.000 ... 54 ... 1500 



M81 ... 172,000 ... 18 ... 900 



.Mioi ... 289,000 18 1500 



M5I ... 370,000 ... 10 I ICO 



H524 ... 500,000 15 ... 2200 



H476 522,000 ... 7 ... IIOO 



11,56 ... 578,000 ... 8 ... 1300 



Observations at the Moscow Observatory. — The fifth 

 volume of the Amiales de I'Obscrvatoire astronomique de 

 Moscou is a handsome volume, in which Prof. Ceraski 

 publishes numerous results derived from various observa- 

 tions made since the new observatory was installed in 

 1900 ; the frontispiece is a reproduction of a photograph 

 of the new buildings. 



Among other results. Prof. Ceraski gives those obtained 

 for the stellar magnitude of the sun in two separate re- 

 searches in 1903 and 1905. In the first he compared the 

 sun with Venus, and then, in the evening, Venus was 



NO. 2206, VOL. 88] 



compared with a Leonis. The sun was found to be 

 242,4o<>,ooo,(x)o times brighter than the star, and, taking 

 Miiller's magnitude (1-57) for a I^'onis, the sun's magni- 

 tude is -26Ht). In the later research other stars were 

 also employed, and — 26-5 was obtained as a more trust- 

 worthy value of the sun's magnitude. 



Other papers deal with the angular velocities of Perseid 

 meteors, a special eyepiece for solar observations, a 

 method of utilising the sun's heat, the intensity of the 

 luminosity of the atmosphere near the sun's limb, &c. 

 Further, M. Sternberg has a long paper on the application 

 of photography to the measures of double stars, and M. 

 Blazko writes concerning Algol variables, and describes a 

 type of slitless spectroscope. In the appendix a large 

 number of photographs showing the regions around 

 variable stars, discovered by Madame Ceraski, are re- 

 produced. 



Internal and Cloi-d Velocities of (iRoups of Stars 

 IN Relation to Spectral Type. — In No. 5, vol. xxxiv., 

 of The Astrophysical journal. Dr. Weersma arrives at 

 some interesting results arising from a mathematical 

 inquiry into the ratio between the linear velocities 

 of the individual members of star groups and the general 

 velocities of the groups as a whole, as it exists in different 

 spectral types. Prof. Kapteyn, in a paper published in 

 1910, found that the individual linear velocities of stars 

 increase with age, and suggested that this phenomenon 

 probably entails a dissipation of star groups as they grow 

 older. Dr. Weersma now shows, from a study of A-type 

 and K and M-type stars, that this suggestion is probably 

 correct. He finds that the individual velocities do tend to 

 increase with age, while there is apparently a tendency 

 for the group velocities to diminish ; the evidence for the 

 latter, however, is by no means conclusive. 



SILK-CULTURE IN THE PHILIPPINES.' 



CILK production is one of the most important industries 



•^ in most of the warmer parts of the world ; but the 



mulberry silkworm, Bonibyx mori, still supplies by far 



the largest proportion of this commodity. 



As regards the Philippines, although the Jesuit Father 

 Antonio Sedwo made large plantations of mulberry in 

 1593, and introduced silkworms, and in 1780 the 

 Augustinian missionary Father Manuel Galiana sent both 

 mulberries and silkworm eggs from China, and the silk 

 industry was carried on for a while with success, yet it 

 seems subsequently to have been neglected until about six 

 years ago, when the Bureau of Science again introduced 

 mulberry silkworms into the Philippines, under the auspices 

 of the American Government, which, at the same time, 

 promulgated an .Act forbidding the introduction of silk- 

 worms into the Philippines by unauthorised persons. 



This was due to the fear of the probable importation of 

 silkworm diseases ; but it may also be pointed out that the 

 introduction of that terrible pest the gipsy moth into 

 America was due to an entomologist carrying on experi- 

 ments with possible silk-producing moths ; and great care 

 should always be taken in introducing an animal or plant 

 into a new country, as it sometimes becomes an unexpected 

 pest, even though it may be innocuous in its native home. 



The Bureau of Science began by importing the eggs of 

 silkworms from Japan in 1905, but it was found impossible 

 to preserve the eggs of the next brood. Therefore, in 1907, 

 cocoons of four different varieties were obtained from 

 Ceylon, and these proved to be a great success. The 

 pamphlet before us gives a full history of the development 

 and management of the insects in all their stages. 



Having succeeded so far, the Bureau of Science 

 attempted in 1909 to introduce the Eri, or castor-oil silk- 

 worm, Attacus ricini, belonging to another family of silk- 

 producing moths, also from Ceylon. The treatment of the 

 silk produced by this insect is different from that used for 

 the mulberry silkworm, for the moth must not be allowed 

 to emerge from the cocoon, and the cocoons cannot be 

 reeled, but must be spun like wool or cotton, though when 

 thus treated they yield a very fine silk. 



» " A Manual of Philippire Silk Culture." By Charles S. Banks. (From 

 the Entomological Section, Biological Laboratory, Bureau of Science, 

 Manila). Pp. 534-xx plates. (Manila : Bureau of Printing, 1911.); 



