on the Optical Phenomena of the Atmosphere. 

 Table {continued). 



97 



In comparing the results given by the cyanometer for higher 

 and lower situations, it will be most advantageous to choose those 

 which may be regarded as maxima, as these only arc free from 

 disturbances, and hence most capable of being compared with 



* The zenith distances were determined by a suitable instrument, as the 

 ■pparently compressed shape of the firmament always causes considerable 

 (•nor in mere estimation. At great elevations the firmament appears much 



lower than from lower positions. 



Phil. May. S. 4. Vol. 3. No. 16. Feb. 1852. H 



