450 



SCIENCE. 



[N. S. Vol. XXIII. No. 586. 



The Solar Corona, as observed hy the V. 8. 



Naval Observatory Eclipse Expedition, 



August 30, 1905, at Porta Cceli, Spain: 



G. H. Peters. 



The observing station was near the east- 

 ern coast of Spain, north of Valencia. It 

 was located about ten miles north of the 

 southern limit of the shadow path, for the 

 purpose of studying especially the regions 

 about the southern pole of the sun. 



The corona at this eclipse, occurring near 

 the sun-spot maximum, had a structure 

 entirely different from those of 1900 and 

 1901. The polar rays were nearly oblit- 

 erated by numerous streamers and wings, 

 which were nearly equally prominent 

 throughout the whole circumference. The 

 entire corona exhibited a mass of fine de- 

 tails, considerably striated, and to a great 

 extent intermingled. 



Vacant Regions of the Sky: E. E. Barnard. 



There are two distinct classes of these 

 vacancies. The commonest form has all 

 the appearance of real openings in the bed- 

 work of stars— through which there is an 

 uninterrupted view of space. The other 

 class, mainly found in Ophiuchus and 

 Scorpio, suggest the presence of a nebulous 

 substratum among the stars. The appeax-- 

 ance of these latter regions is widely dif- 

 ferent from ordinary vacancies, their 

 marked features being areas devoid of 

 stars, yet apparently filled with some other 

 substance in which blacker holes occur, as 

 if there were a nebulous veiling pierced 

 with holes and rifts. 



The most remarkable of these regions are 

 those about 6 and p Ophiuchi, the latter 

 being connected with the great nebula of 

 P Ophiuchi. From this latter region a 

 straggling vacant lane runs easterly for a 

 distance of some 15° and connects with a 

 great chasm just east of 6 Ophiuchi. Some 

 vacancies near this latter star are very 

 small and very curious, all showing more 



or less the appearance of vacancies within 

 vacancies. 



Attention is called to the probable rela- 

 tive smallness of stars forming the bed- 

 work of the Milky Way near Antares. 

 The small stars here seem to be intimately 

 related to the great nebula of p Ophiuchi. 

 But the nebula certainly involves such 

 naked eye stars as p Ophiuchi and a Scor- 

 pii, and appears to involve even Antares. 

 Eeasoning from this that the nebula, the 

 small stars of the Milky Way, and the 

 brighter stars here, are at relatively the 

 same distance from us, the natural conclu- 

 sion is that the apparently great difference 

 in size between the above-named stars and 

 the groundwork of small stars of the Milky 

 Way at this point is not so much due to a 

 greater distance of the smaller stars as to 

 their being actually very much smaller. 



Determination of Absolute Star Positions 

 by Photography : B. C. Pickering. 

 It is proposed to determine the absolute 

 positions of a zone of equatorial stars by 

 means of photography. A telescope of 

 long focus is pointed to the intersection 

 of the equator and meridian, and motion is 

 given to the photographic plate equal to 

 that of the stars. Reference points are 

 furnished by holes through which a small 

 incandescent light shines on the plates. 

 Current is sent from a standard clock, 

 which should be kept underground at a 

 uniform temperature and pressure. As 

 observations would extend over one .year 

 at lea.st, errors depending on the sun's posi- 

 tion should be eliminated. The only parts 

 of the apparatus that need be rigid are the 

 objective and the plate carrying the refer- 

 ence holes. So long as the images, which 

 have an exposure of about a minute, are 

 sensibly circular, or uniformly elongated, 

 slight motions of the photographic plate 

 are unimportant. The principal advantage 

 of this method is that stars as faint as the 



