354 



NATURE 



[May 20, 1909 



equatorial belt was divided into two parts by a longitudinal 

 belt practically encircling the planet. 



On March 30, at sh. 55m. (standard mountain time), 

 the shadow of satellite I. was seen to be nearly twice as 

 troad as it was high, and at 6h. 13m. a penumbra to it 

 was observed. Markings were seen on satellite III. on 

 April 2. 



The Upper Layers of the Solar Atmosphere. — In a 

 paper published in No. 16 (April ig) of the Comptes rendus 

 M. Deslandres describes some results obtained with his 

 new spectroheliograph. Photographs obtained previously 

 showed long dark streaks of calcium vapours when the 

 secondary slit was set on the centre of the "K" line; 

 these streaks were named " filaments." 



By employing a larger dispersion and an additional slit 

 of an improved form, M. Deslandres succeeded in isolating 

 entirely the K, line, and found that these filaments were 

 shown much more definitely than on the earlier negatives, 

 when the light employed was a mixture of the K, and 

 K3 lines. A similar result follows if the Ha line of 

 hydrogen be employed. These dark filaments, then, are 

 the characteristic feature of the sun's upper atmosphere, 

 and differ from Hale's " dark flocculi " in that they are 

 black on both the K, and Ha (centre of line) photographs. 



In the same number of the Comptes rendus Prof. Hale 

 makes some remarks relative to Dcslandres's paper, and 

 states that on employing the large spectroscope he found 

 that the relative intensity of the bright and dark flocculi 

 depends upon the part of the line (Ha) employed. With 

 the slit set on the central part of the line the bright flocculi 

 are very intense, but if the light from the edge of the 

 line is exclusively used, the dark flocculi are shown 

 strongly, whilst the bright flocculi are faint or even 

 invisible. 



Spectra of some Spiral Nebulae and Globular Star 

 Clusters. — With a specially designed spectrograph 

 attached to the Crossley reflector, Mr. E. A. Fath has 

 succeeded in photographing the spectra of a number of 

 spiral nebulte and globular clusters, the investigation 

 having been undertaken in order to test the statement that 

 the spectra of the former are continupus. The collim.itor 

 of the spectrograph has an aperture of 54 mm. and a 

 focal length of 315 mm., and the prism is of light flint 

 glass and 30° angle, whilst the camera objective is com- 

 posed of two plano-convex lenses of 51 mm. aperture 

 and 155 mm. equivalent focal length. The scale of the 

 spectrum is such that the distance from \ 3727 to X 5007 

 on the plate is approximately 3-3 mm. ; exposures varying 

 from 3h. 19m. to iSh. iim. — for the Andromeda nebula — 

 were found necessary. 



There is not space here to reproduce the detailed dis- 

 cussion given in Lick Observatory Bulletin No. 149. but 

 the general conclusions are of great interest. No spiral 

 nebula investigated has a truly continuous spectrum, 

 although this is the fundamental feature of all their 

 spectra, which range from those having principally bright 

 lines to those containing only absorption lines of the solar 

 type. The great nebula in Andromeda comes in the latter 

 category, and fourteen absorption lines were measured. 



The spectra of the spiral nebulae are best interpreted by 

 the hypothesis that these bodies are unresolved star 

 clusters with varying conditions of gaseous envelopes. 

 Thus, if the Andromeda nebula were such a cluster in 

 which stars of the solar type preponderated, its spectrum 

 would be sufficiently explained. The exposures on globular 

 clusters showed that clusters in which one spectral type 

 of star predominates do exist. But this question needs a 

 great deal more investigation before the theorv can be 

 accepted, and, as Mr. Fath points out, Bohlin's parallax 

 for the Andromeda nebula, 0.17", would require that, if 

 this object is an unresolved star cluster, the size of the 

 components is, with reasonable assumptions, of the order 

 of that of the asteroids. The difficulty of the investigation 

 lies in the extreme faintness of the objects to be observed. 

 While two minutes' exposure on Arcturus, with the Mills 

 spectrograph attached to the 36-inch refractor, gives a 

 measurable spectrum, it would require about .^00 hours 

 to give a satiiifactory spectrum of the Andromeda nebula, 

 one of the brightest of the spiral nebulae. 

 NO. 2064. VOL. 80] 



THE INTERNATIONAL COMMISSION FOR 

 SCIENTIFIC AERONAUTICS. 



THE sixth Congress of the International Commission, 

 for Scientific Aeronautics commenced at Monaco on 

 April 1. Thirty-three members were present, representing, 

 fourteen countries. The Prince of Monaco, by whose 

 invitation the meeting was held at Monaco, placed the 

 rooms of the new Oceanographical Museum at the service 

 of the commission. Among the members present were 

 Prof. Hergesell (the president), Profs. Assmann,' Berson,, 

 and Captain Hildebrandt from Germany, M. Teisserenc 

 de Bort from France, Prof. Hildebrandsson from Sweden^ 

 Prof. A. L. Rotch from the United States, Generals 

 Rykatcheff and Kowanko from Russia, Colonel Vives y 

 Vich from Spain, Prof. Bjerknes from Norway, Prof. 

 Palazzo and Dr. Oddone from Italy, Hofrat von Konkoly 

 from Hungary, M. Vincent from Belgium, Captain Ryder 

 from Denmark, and Messrs. P. Alexander and C. J. P. 

 Cave from this country. 



Prof. Hergesell, in opening the congress, spoke of the 

 extent of the observations now made by members of the 

 commission, and of the work that had been done since 

 the last meeting at Milan. He mentioned particularly the 

 series of ascents made in July, 1907, the full results of 

 which had just been published, and which included a 

 network of observations extending over a great pari of 

 the northern hemisphere. The instruments used were very 

 satisfactory, but Prof. Hergesell warned observers to make 

 frequent calibrations to ensure accuracy in the observa- 

 tions. He also mentioned the important work on wind' 

 direction and velocity by means of theodolite observations 

 on halloiis sondes and pilot balloons. 



The Prince of Monaco, in welcoming the congress, spoke 

 of the work that had been done by Prof. Hergesell and 

 himself on his yacht the Princcsse Alice, and of the find- 

 ing of ballons sondes at sea. By means of observations 

 to determine the trajectory. Prof. Hergesell was able to 

 determine the point of fall with such accuracy that 

 balloons are now found at sea more easily than on land. 



At the morning meeting on April 2 Prof. Assmann 

 read a paper on rubber balloons, and spoke of the improve- 

 ment that had lately been made in their manufacture ; it 

 had been found possible to eliminate small foreign particles 

 in the rubber, which consequently could be stretched far 

 more before bursting occurred. M. Teisserenc de Bort 

 spoke of goldbeater's skin for captive balloons, and men- 

 tioned that, by a system of elastic lacing, expansion could 

 be secured during the ascent and " pocketing " avoided 

 during the descent. Prof. Hergesell spoke of the rapid 

 deterioration of rubber balloons owing to the effect of 

 light, especially in the tropics ; to guard against this Prof. 

 Assmann uses a yellow covering for captive rubber 

 balloons. 



Prof. Assmann then read a paper on a method of ventil- 

 ating the instrument for a short time during an ascent, 

 when, owing to decrease of vertical velocity, insolation 

 might cause too high a temperature to be recorded ; the 

 apparatus consists of a polished metal sphere containing 

 compressed air, which can be opened by an electric con- 

 tact actuated bv the barometer at any desired height. He 

 spoke of the doubts that had been expressed, particularly 

 in England, on the reality of the isothermal layer, or 

 " stratosphere " as it has been named by M. Teisserenc 

 de Bort, and hopes that his apparatus may definitely set 

 these doubts at rest. Mr. Cave said that no one in 

 England who is working at the study of the upper air 

 has any doubts as to the realitv of the stratosphere ; Prof. 

 Hergesell cited cases of rapid descents of instruments, 

 and M. Teisserenc de Bort mentioned night ascents as 

 proving the real existence of the phenomenon. Prof. 

 Hergesell noticed that no member present croubted the fact, 

 and asked the secretaries particularly to note this agree- 

 ment of ooinion. 



Prof. Hergesell showed a new meteorograoh for use 

 with manned and captive balloons. Prof. Palazzo an 

 apparatus for detaching balloons, and similar instruments 

 were shown by Prof. Hergesell and General Rykatcheff. 

 M. Teisserenc de Bort deprecated the idea of limiting the 

 ascent of a ballon sonde. 



