6. NOTE ON A METHOD OF VIEWING THE SOLAR PROMINENCES WITHOUT AN ECLIPSE. BY WILLIAM HUGGINS, F.R.S.1 "Last Saturday, February 13, 1869, I succeeded in seeing a solar prominence so as to distinguish its form. A spectroscope was used; a narrow slit was inserted after the train of prisms before the object-glass of the little telescope. This slit limited the light entering the telescope to that of the refrangibility of the part of the spectrum immediately about the bright line coincident with c. The slit of the spectroscope was then widened sufficiently to admit the form of the prominence to be seen. The spectrum then became so impure that the prominence could not be distinguished. A great part of the light of the refrangibilities removed far from that of c was then absorbed by a piece of deep ruby glass. The prominence was then distinctly seen." 7. EXTRACT FROM ZÖLLNER-DESCRIPTION OF PROTUBERANCES.2 (See Figs. 71 to 75.)

"One of the most remarkable forms is that shown on Fig. 72. I scarcely believed my eyes when I noticed in this one the flickering motion of a flame. This motion was, however, slower in proportion to the dimensions of the protuberance than that of a large mass of ordinary flame. The time needed for the propagation of this flame-wave from the base to the point of the prominence amounted to about from two to three seconds. Fig. 71 exhibits good examples of the rate of change which the form and intensity of these prominences undergo. The time at which each form was observed is given underneath each figure. Most of the prominences exhibit forms analogous to those of the various clouds and mists occurring in our atmosphere; of these, the cumulus type is the commonest. The flame-like pro

tuberance Fig. 72 is an exception to the ordinary form; and in the forms of Figs. 73, 74, and 75, it is almost impossible to help believing that the masses which are seen to rise from the sun's surface are immediately connected with the cloudy portions which float above, and one is forcibly reminded of the phenomena of the eruptions of volcanoes or geysirs."

1 Proc. Roy. Soc. vol. xvii. p. 302. 2 Pogg. Ann. cxxxvii. p. 624.

LECTURE VI.

Planet and Moonlight.-Stellar Chemistry.-Huggins and Miller.— Spectra of the Fixed Stars.-Difficulties of Observation.—Methods employed. Variable Stars.-Double Stars.-Temporary Bright Stars.-Nebulæ.-Comets.-Motion of the Stars (Huggins).— Determinations of Velocity of Solar Storms (Lockyer).

APPENDIX A.-Extract from a Memoir "On the Spectra of some of the Fixed Stars."

APPENDIX B.—"On the Spectrum of Mars, with some Remarks on the Colour of that Planet."

APPENDIX C.-"On the Occurrence of Bright Lines in Stellar Spectra," and "On the Spectra of Variable Stars."

APPENDIX D.-"Further Observations on the Spectra of some of the Stars and Nebulæ, with an attempt to determine therefrom whether these Bodies are moving towards or from the Earth; also Observations on the Spectra of the Sun and of Comet II. 1868." APPENDIX E.-"Researches on Gaseous Spectra in relation to the Physical Constitution of Sun, Stars, and Nebula."

APPENDIX F.-"On a new Spectroscope, and Contributions to a knowledge of the Spectrum Analysis of the Stars." Notice of Browning's new Automatic Spectroscope.

IN the last lecture I endeavoured to point out to you the principles upon which Professor Kirchhoff arrived at the remarkable conclusion that certain metals well known on earth are contained in the solar atmosphere. I have to-day to bring before you facts which are still more interesting, with regard to the chemical composition of the stars and the nebula; and if in the former lectures I had to couple the names of two great German philosophers, I have to-day to bring before your notice the