J. W. Draper—Phosphorograph of a Solar Spectrum. 179 
commonly use as an extinguisher, no effect was produced by 
o 
rays must be adjusted in intensity to each other.” It requires 
a powerful yellow ray to antagonize a feeble daylight. 
t is owing to the difference in amplitude of vibration that 
the heat of radiation seems so much more effective than the 
heat of conduction. A temperature answering to that of the 
boiling point of mercury must be applied to a phosphorescent 
tablet for quite a considerable time before all the light is extin- 
guished. But the red end of the spectrum and that even of 
the diffraction spectrum, in which the heat can with difficulty 
be detected by the most sensitive thermometer, accomplishes it 
very quickly. 
VI. Or tue Inrra-rep Lines on BANDS IN THE Sun’s SpEc- 
At a distance about as far below the red as the red is below 
the yellow in the solar spectrum, I found in 1842, in photo- 
graphs taken on iodide of silver (Daguerre’s preparation), three 
great lines or bands, with doubtful indications of a fourth still 
further off. I designated them as a, f, 7, and published an 
ee of them in the Philosophical Magazine for May, 
In 1846, MM. Foucault and Fizeau having repeated the 
€xperiment, thus originally made by me, presented a communi- 
cation to the French Academy of Sciences. They had observed 
the antagonizing action above referred to, and had seen the 
infra-spectral lines a, 8,7. They had taken the precaution to 
€posit with the Academy a sealed envelope, containing an 
