ASTRONOMY. 199 



off and carries the picture of the corona out to GO' from the Sun's limb. 

 Thus the pictures made by the Naval Observatory parties cover the 

 whole ground, and are far more complete than those of any i)revious 

 eclipse. They are not adequately discussed, however, in the volume be- 

 fore us, which is the less excusable as Mr. Ranyard in his recent work 

 on Solar Eclipses has given a practical example of how such work ahould 

 be done. 



Some idea of the fullness with which these collected reports treat 

 nearly everything which can be made the subject of observation may be 

 had by a glance at the subject-index. For exami^le, the contacts were 

 observed at over twenty stations by more than twenty-five observers. 

 Descriptions of the corona are given on thiity-uine different pages, and 

 these do not include the thirty or more drawings. Nearly every one oi 

 the phenomena is attested by more than one observer of the many en- 

 gaged. Thus the corona was seen before or after totality at six stations. 

 Ten persons swept in the vicinity of the Sun for the discovery of Vul- 

 can. Prof. Watson reports the discovery of two planets, Mr. S\yipt 

 that of two different ones, making four in all, seen or suspected. The 

 report shows that four persons swept over the place of Watson's («) 

 without seeing any planet there, and four also swept over the place 

 of Swift's two, also without seeing them. In all these cases the tel- 

 escopes were of adequate i)ower to have shown the objects of Watson 

 and Swift. 



The main results of the eclipse of 1878 may be summed up much as 

 follows: 



The connection between the activity' of the Sun's surface, as evinced 

 by the number and size of the spots and protuberances, and the nature 

 of the corona, has been again shown. The corona in 1878 was far sim- 

 pler in general character than those of 1800 and 1870. It was observed 

 to extend to a much greater distance from the Sun in this eclipse than 

 in any other, but this is probably due to specially advantageous circum- 

 stances. Professors Newcomb and Langley both observed the corona 

 with the naked eye, extending 5° or 6"^ from the Sun's center. There is 

 much difference of opinion as to the brightness of this corona; it prob- 

 ably was not materially fainter than that of 1809. Photometric observa- 

 tions were made at Pike's Peak upon this point, but there are no earlier 

 observations easily comparable. The most important point of difference 

 between the coronas of 1809 and 1878 was in their spectra. The bright 

 lines due to the gaseous parts were consi)icuous in 1809, while in 1878 

 they were so faint as only to be seen by a few observers, though these 

 lines were undoubtedly present. A continuous spectrum was seen by 

 most spectroscopic observers. The 1474 line was seen at the beginning 

 and end of the eclipse, but only a few observers saw it during the whole 

 of totality. Prof. Eastman traced this line all round the Sun, find- 

 ing it equally bright at equal distances from the center, and what is re- 

 markable, finding no defect in the brightness of this line in the points 



