154 ASTRONOMY FOR IH89, 1890 



protiiheraiUH's were seen, according to Tacchini, in hotli hemispheres at 

 hiy,h latitiiilcs where tliere were ueither spots nor lacuhe; tliore were 

 also zones with spots and without facul«i. 



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

 mittee ou the observations ofsuu-spot spectra made at South Kensing- 

 ton. He finds that the observations (to February, 18S8) confirm the 

 conclusion which he arrived at in 1880, that " as we pass from minimum 

 to maximum the Hues 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 1879 ThoUon presented to 

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

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

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

 taking he confined himself to the region from A to 6; this was pre- 

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

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

 33 maps with a total length of 10'". 23 (33.0 feet), and contains about 3,1200 

 lines, between the limits adopted, A and /», the {)ositions of which were 

 determined from 252 sharp lines adopted as "fundamentals." 



Thollou made special ettbrts to distinguish the telluric rays from those 

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

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

 these 3,200 lines mapped, 2,090 were of solar origin, 80(5 telluric, and 

 2-16 mixed, that is to say resulting from the superpositioii of telluric and 

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

 arbitrary scale. 



M. Bigourdan, in a review of Thollon'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 Thollou 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-'engths 5,202 and 5,337, for example, in Rowland's pho- 

 tograi)h, there are not half the number of lines that there are upon 

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

 not show so large a difference. 



RoiclaniVs dctermijintion of elements in the sun. — Professor Rowland's 

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

 parison with the si>ectrum of the sun shows the existence in the sun of 

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

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

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



