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absorbing absorption acid analysis appear APPENDIX atmosphere bands becomes blue bodies bright lines carbon cause chemical chloride coincident colour comet compared compound consists contains continuous corresponding dark lines detected determined direction distance distinct double earth effect electric elements emitted employed examined existence experiments fact Fe Fe Fe flame gases give given glass green heat Huggins hydrogen inch increased indicate intensity iron Kirchhoff Lecture length less light lithium luminous matter means measured metals method miles motion nature nebula nitrogen noticed observed obtained pass Phil placed plate portion position present prism probably produced prominences quantity rays reference reflected refrangible salts scale seen Series slit sodium solar spectrum spark spectra spectroscope stars strontium substance telescope temperature tube vapour violet visible wave-length whilst wire yellow
Page 102 - The colours thus communicated by the different bases to flame afford, in many cases, a ready and neat way of detecting extremely minute quantities of them...
Page 261 - The solar and atmospheric spectra being hidden, and the image of the wide slit alone being visible, the telescope or slit is moved slowly, and the strange shadow-forms flit past. Here one is reminded by the fleecy, infinitely delicate...
Page 300 - Here one is reminded, by the fleecy, infinitely delicate cloud-films, of an English hedgerow with luxuriant elms ; here of a densely intertwined tropical forest, the intimately interwoven branches threading in all directions, the prominences generally expanding as they mount upwards, and changing slowly, indeed almost imperceptibly.
Page 219 - Below the prism is an achromatic eye-piece, having an adjustable slit between the two lenses, the upper lens being furnished with a screw motion to focus the slit. A side slit, capable of adjustment, admits, when required, a second beam of light from any object whose spectrum it is desired to compare with that of the object placed on the stage of the microscope. This second beam of light strikes against a very small prism, suitably placed inside the apparatus, and is reflected up through the compound...
Page 242 - ... not appreciably alter when the sun approaches the horizon. It does not, on the other hand, seem at all unlikely, owing to the high temperature which we must suppose the sun's atmosphere to possess, that such vapours should be present in it. Hence the observations of the solar spectrum appear to me to prove the presence of iron vapour in the solar atmosphere with as great a degree of certainty as we can attain in any question of natural science.
Page 41 - The homogeneal light and rays which appear red, or rather make objects appear so, I call rubrific or red-making; those which make objects appear yellow, green, blue, and violet, I call yellowmaking, green-making, blue-making, violet-making, and so of the rest.
Page 37 - Now the different Magnitude of the hole in the Window-shut, and different thickness of the Prism where the Rays passed through it, and different inclinations of the Prism to the Horizon, made no sensible changes in the length of the Image. Neither did the different matter of the Prisms make any : for in a Vessel made of polished Plates of Glass cemented together in the shape of a Prism and filled with Water, there is the like Success of the Experiment according to the quantity of the Refraction.
Page 427 - There are in the stars already observed exceptions to this general statement ; and there are some other considerations which appear to show that the sun's motion in space is not the only, or even in all cases, as it may .be found, the chief cause of the observed proper motions of the stars*.
Page 42 - Another interesting practical application of our knowledge concerning the properties of the kind of light which certain bodies emit when heated, is the employment of the light evolved by burning Magnesium wire for photographic purposes. The spectrum of this light is exceedingly rich in violet and ultra-violet rays, due partly to the incandescent vapour of magnesium, and partly to the intensely-heated magnesia formed by the combustion. Professor Bunsen and the speaker in 1859 determined the chemically...