154 ASTRONOMY FOR 1889, 1890. 



protuberances were seen, according to Tacchiui, in both hemispheres at 

 high hititudes where there were neither spots nor facnln^; there were 

 also zones with spots and without faculse. 



Mr. Lockyer has presented a second report to the Solar Physics com- 

 mittee ou the observations of sun-spot spectra made at South Kensing- 

 ton. He finds that the observations (to February, 1888) confirm the 

 conclusion which he arrived at in 1S8G, that " as we pass from minimum 

 to maximum the lines of the chemical elements gradually disappear 

 from among those most widened, their places being taken by lines of 

 which we have at present no terrestrial representatives. 



SOLAR SPECTRUM. 



Thollon's chart of the solar spectrum. — In 1870 Thollon presented to 

 the Academic des Sciences a map of the solar spectrum, extending from 

 A to H, made with his great spectroscope. His work was renewed with 

 more perfect apparatus, but ou account of the great labor of the under- 

 taking he confined himself to the region from A to b; this was pre- 

 sented to the Academy in 1885, and gained the Lalande prize. Thollon 

 continued this work until his death, and it has now been published in 

 33 maps with a total length of 10'". 23 (o3.G feet), and contains about 3,200 

 Hues, between the limits adopted, A and Z', the positions of which were 

 determined from 252 sharp lines adopted as " fundamentals." 



Thollon made special efforts to distinguish the telluric rays from those 

 entirely due to the sun; and with this end in view he observed the .sun 

 at different altitudes, noting the hygrometric conditions of the air. Of 

 these 3,200 lines mapped, 2,090 were of solar origin, 866 telluric, and 

 246 mixed, that is to say resulting from the superposition of telluric and 

 solar lines. The breadth and intensity of each line is given upon an 

 arbitrary scale. 



M. Bigourdan, in a review of Tliollon's work, published in the May 

 number of the Bulletin Astronomique, says that for the part of the spec- 

 trum studied no work is comparable with that of Thollon except the 

 magnificent photographs of Rowland, and he finds upon a critical com- 

 parison of different regions of considerable extent that Rowland's pho- 

 tographs contain no lines not upon Thollon's chart, though the faintest 

 lines given upon the chart are frequently lacking in the photographs. 

 Between wave-lengths 5,262 and 5,337, for example, in Rowland's pho- 

 tograph, there are not half the number of lines that there are u])on 

 Thollon's chart, though it is probable that the original negatives would 

 not show so large a difference. 



Bowland\s determination of elements in the sun. — Professor Rowland's 

 examination by photography of the spectra of 58 elements and their com- 

 parison with the spectrum of the sun shows the existence in the sun of 

 35 different elements ; the existence of 8 more in the sun is doubtful, 

 while of 10 he finds no trace. The element represented by the greatest 

 number of lines is iron," there being 2,000 or more Hues in the spectrum 



