THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JANUARY 1852. 



I. Observations in the Alps on the Optical Phenomena of the 



Atmosphere. By Dr. Hermann Schlagintweit*. 



[With a Plate.] 



Deportment of the atmosphere towards heat and light. 

 Transmission of heat. Pyrheliometer. Difference of the thermo- 

 meter in the sun and in the shade. Thermometer with blackened bulb. 

 Saussure's heliothermometer. Nightly radiation. Transparency. 

 Absorption of light in general. Diaphanometer. Transparency of the 

 atmosphere in large masses. Optical illusions through altered transpa- 

 rency. 



AMONG the optical phenomena of the atmosphere, those 

 which relate to its colour and its deportment towards the 

 rays of light and heat are peculiarly subject to alteration with the 

 height. The investigation of this subject at great elevations, as, 

 for instance, in the higher alpine regions, obtains an interest 

 from the fact, that here, in regard to its weight, a considerable 

 portion of the atmosphere is absentf- 



The experiments on the intensity of heat and light are, how- 

 ever, subject to so many accidents and disturbances, that in the 

 following pages we must sometimes limit ourselves to the results 

 of single experiments. 



Transmission of Heat. 



To convince ourselves of the high permeability of the atmo- 

 sphere with regard to the rays of heat, we made use of one of 



* Extracted from the Researches on the Physical Geography of the Alps, 

 by Hermann Schlagintweit and Adolph Schlagintweit. Leipzig. T. A. 

 Bartb, 1850. 



t At a height of 1 2,000 feet the loss, in this respect, amounts to 037 ; 

 at 14,500 feet, to 044 of the entire weight. 



Phil. Mag. S. 4. Vol. 3. No. 15. Jan. 1852. B 



