68 The Greed Solar Ediiise [Jan., 



desired extent by distribution over a large area, "wliereas the same 

 amount of dispersion merely places the luminous bands of the 

 former spectrum farther apart, without -weakening them to any 

 extent. If therefore the red flames gave a spectrum of bright 

 lines, they would become visible by examination under sufficient 

 dispersive power. ]\Ir. Lockyer, satisfied that his want of success 

 was owing to deficient power or want of adjustment in his instru- 

 ment, applied himself to construct a more powerful spectroscope, 

 which was completed in October last. With this he was soon 

 rewarded by the sight of a prominence spectrum, an account of 

 wliich was forwarded to the Eoyal Society, on October 20 th, in 

 the following words :— " I have this morning perfectly succeeded 

 in obtaining and observing part of the spectrum of a solar pro- 

 minence. As a result I have established the existence of three 

 bright lines in the following positions : — 



I. Absolutely coincident with c. 



II. Nearly coincident with r. 



III. Near d. 



" The third line (the one near d) is more refrangible than the 

 more refrangible of the two darkest lines, by eight or nine degrees 

 of KirchhofF's scale." 



In a subsequent communication to Dr. De la Kue, Mr. Lockyer 

 says that he has been able to recognize that the protuberances arc 

 simply local accumulations of a gaseous envelope, which completely 

 surrounds the sun, for in all parts of the circumference he perceives 

 the characteristic spectrum of the protuberances. The thickness of 

 this new envelope is said to be nearly 5000 miles, and it is mar- 

 velously regular in its contour, at the pole as at the equator. A 

 prominence gives a spectrum consisting of a few long bright hues, 

 but on directing the instrument to the extreme edge of the sun, 

 and with the slit perpendicular to its tangent, a narrow belt of the 

 true solar spectrum is seen, fringed with that of the new enveloiDC, 

 consisting of a few very short bright lines projected on a very 

 faint continuous spectrum of diffused daylight. The bright lines 

 being superi)osed on or forming a prolongation of the solar 

 spectrum, it is easy to ascertain with great accuracy whether they 

 coincide with any of Fraiinhofer's lines ; the dark hne sometimes 

 being obliterated and at other times being prolonged by the bright 

 one. If the instrument adjusted in this manner to the extreme 

 edge of the sun be now gradually swept round the circle, when a 

 prominence is reached the narrow S2")ectrum of the chromos])liere, as 

 Mr. Lockyer has termed his new solar envelope, begins to lengthen, 

 and by measuring the length of the luminous lines in different 

 parts of the circle, it is easy to map out the shape and position of 



