visible in the Solar Spectrum. 5 



Fraunhofer-lines ; namely, that the lines belonging to the air 

 or to the gas through which the electric spark passes, are less 

 sharply denned and diffuse themselves more in proportion as the 

 strength of the electricity is increased, whereas the metal-lines, 

 especially those belonging to metals of high fusion-temperature, 

 like iron, are very sharply defined. 



On a careful examination of the solar spectrum, one can often 

 discover certain lines imbedded as it were in a mass of fainter 

 lines, which with increased illumination seem to withdraw them- 

 selves and disappear, while the first-mentioned lines, on the con- 

 trary, only stand out in stronger relief. These are metal-lines, 

 and the most remarkable among them almost invariably belong 

 to iron. 



Thus between H and G we have fifteen stronger iron-lines, 

 all having their counterparts in the solar spectrum. The two 

 strongest of these lie at about J and J of the distance between 

 H and G, and that nearest to G is double, as belonging also to 

 calcium. Moreover, at G and in its immediate neighbourhood 

 towards F, we have five strong besides eight fainter lines, at F, 

 again, five, and, lastly, around E a numerous group, all answering 

 to dark lines in the solar spectrum. 



We may add to KirchhofFs statement concerning magnesium, 

 that the third of the lines marked b, reckoning towards F, is 

 double, and belongs accordingly both to magnesium and iron. 



To the four bodies which Kirchhoff has thus shown to exist in 

 the sun, we may, as the result of our own researches, add calcium, 

 aluminium, and manganese, as also in all probability strontium 

 and barium. 



Calcium has three strong lines at the violet end of the spec- 

 trum, of which two are especially remarkable as answering to 

 the H lines, and the third in order forms, together with one of 

 the iron-lines, the before-mentioned strong double line. Calcium 

 has furthermore six lines coinciding with lines of the G group, 

 three between G and F, and, lastly, groups of fine lines at E, and 

 between E and G. 



Aluminium is especially characterized by two strong lines 

 lying between the H lines of the solar spectrum, and there 

 corresponding to two dark lines. Between H and G, aluminium 

 probably forms a continuous spectrum. The aluminium-lines 

 in the remaining portion of the spectrum are less prominent; 

 and accordingly, the corresponding lines of the solar spectrum 

 cannot with certainty be determined. 



The manganese-spectrum contains a considerable number of 

 lines, which in their phenomena very much resemble those of 

 iron. Between G and H, two groups of manganese-lines coincide 

 with two similar groups of iron-lines ; and between G and F are 



