April 30, 1886.] 



SCIENCE. 



387 



the metallic prominences, as a sequel to the spot ; 

 and there is evidence to suggest that a careful 

 study will enable us to see by what process the 

 reaction of the photosphere and underlying gases 

 produced by the fall of spot - material tends to 

 make the spot-material discharge itself in lower 

 and lower latitudes, as the temperature of the 

 sun's lower atmosphere gets enormously increased. 



The observations of Professors Xewcomb and 

 Langley at the minimum of 1878, on the equa- 

 torial extension, are among the most remarkable. 

 Professor Newcomb hid the moon and 12' of arc 

 around it at the moment of totality by a disk of 

 wood, carefully shielding his eyes before totality. 

 Professor Langley observed at a very considerable 

 elevation. It is therefore quite easy to under- 

 stand why this ring has not been seen or photo- 

 graphed at maximum. At maximum no pre- 

 cautions have been taken to shield the eye ; no 

 observations have been made at a considerable 

 elevation ; while the fact that the ring, if it 

 exists, consists of cool material, fuDy explains 

 how it is that the photographic plates have dis- 

 regarded it. 



I would propose, therefore, that the repetition 

 of Professor Newcomb's observations of 1878 be 

 made an important part in the arrangements of 

 the eclipse for this year. A slight alteration in 

 the method will be necessary, as the ring will be 

 near the vertex and the lowest point of the 

 eclipsed sun. 



3. Another point of the highest importance at 

 the present moment has relation to the existence 

 of carbon. Until Tacchini's observations of 1883, 

 the only trace of carbon in the solar spectrum 

 consisted of ultra-violet flutings. He observed 

 other flutings in the green near the streamers in 

 the eclipse referred to. 



Duner's recent work puts it beyond all doubt 

 that stars of class III. b have their visible ab- 

 sorption produced chiefly by carbon vapor. 



On any theory of evolution, therefore, we must 

 expect the sun's atmosphere to be composed to a 

 large extent of carbon at some time or other ; so 

 that the highest interest attaches to this question 

 in connection with the height in the atmosphere 

 at which the evidence of carbon is observed. The 

 existence of the ultra-violet flutings among the 

 Fraunhofer lines tells nothing absolute about this 

 height, although I inferred, at the time I made 

 the announcement, that it existed at some height 

 in the coronal atmosphere. 



These three points, then, are those to winch I 

 attach special importance at the present time. 



We next come to photographs of the corona. 

 I believe, that, with our present knowledge, the 

 chief thing we have to seek in such photographs 



is not merely the streamers and their outlines, 

 which we are sure to get anyway, but images on 

 a larger scale ; so that in a series of short expo- 

 sures we may endeavor to get some records which 

 w T ill eventually help us in determining the direc- 

 tions of the lower currents. At present we do 

 not know absolutely whether these flow to or 

 from the poles. My own impression is that the 

 panaches at the poles indicate an upper outflow. 



In coming to the photo-spectroscopic observa- 

 tions, I am of opinion, that of the two attacks 

 which I first suggested for the eclipse of 1875, 

 and which have also been used in the last two 

 eclipses of 1882 and 1883, one of them should be 

 discarded, and the whole effort concentrated on 

 the other. 



We have learned very much from the use of 

 the prismatic camera, — one of the instruments 

 referred to ; but the results obtained by it are not 

 of sufficient accuracy to enable them to be fully 

 utilized. On the other hand, though the slit 

 spectroscope failed in 1875, it succeeded with a 

 brighter corona and more rapid plates in 1882 ; 

 and, with a proper reference spectrum, every 

 iota of the facts recorded can be at once utilized 

 for laboratory work and subsequent discussion. 



On these grounds, then, I would suggest that 

 slit spectroscopes alone be used for photographic 

 registration. I think falling plates should be 

 used, and that the work should begin ten minutes 

 before totality, and continue till ten minutes 

 after ; provided the slit be tangential, or nearly 

 so, to the limb. 



I may state that arrangements have been made 

 here to take such a series of photographs on the 

 uneclipsed sim ; and, with the improved appara- 

 tus, I am greatly in hopes that we may get some- 

 thing worth having. J. Norman Lockyer. 



DEEP-SEA SOUNDINGS IN THE ATLANTIC. 



The U. S. S. Enterprise, Commander Barker, 

 during her recent passage from Montevideo to 

 Barbadoes, and from thence to New York, made a 

 series of deep-sea soundings through the Atlantic 

 Oceans which add considerably to our knowledge 

 of the depths of those seas. Seventy-two casts 

 were taken between Montevideo and Barbadoes, 

 the distance run being 5,031 miles. 



After leaving Montevideo, the course of the 

 Enterprise was laid to the northward, towards 

 Nelson shoal, where a depth of 2,088 fathoms of 

 water was found, instead of 19 fathoms, as ap- 

 pears on all the charts of that locality. Com- 

 mander Barker says, " From this point I steamed 

 slowly, running from 200 to 250 miles to the north- 

 ward of the Challenger's line, taking casts at in- 



