338 



Mr. J. P. Cooke on the Aqueous Lines 



very imperfectly represented by the woodcut. In addition to 

 these, on the more refrangible side of the space between the two 



Fig. 1. 



January 5, 1866. 



Temperature 10° F. 



Dew-point 1°*5 F. 



1 ~ ^2 



Weight of vapour in one 

 cubic foot of air 



0-81 gr. 



Fig. 3. 



December 26, 1865. 



Temperature 55° F. 

 Dew-point 46° F. 



D x d e I ay (3 D 2 



Weight of vapour in one } , F(! 

 cubic foot of air M*/o grs. 



Fig. 2. 



December 25, 1865. 



Temperature 46° F. 

 Dew-point 33°*4 F. 



D x « |3 D 2 



Weight of vapour in one 1 2>42 

 cubic foot of air J 



Fig. 4. 



November 17, 1865. 



Temperature 70° F. 

 Dew-point 64° F. 



Ill 



118 



D x r/ d e £«y/39- /cD 2 



Weight of vapour in one },-,» 

 cubic foot of air / D0/ ^ s ' 



J) lines, there was a faint but broad nebulous band, barely re- 

 solvable into lines of still lower magnitude*. It is impossible to 

 represent this band accurately with a woodcut ; and the shaded 

 broad band marked k, on the right-hand side of fig. 4, only 

 serves to indicate its position and approximate breadth. 



The 26th of December was also a warm day for the season, 

 with a brilliant sun. At 1 p.m. the dry-bulb thermometer 

 marked 55°, the wet-bulb 50°, and hence the amount of mois- 



* We use this word in the same sense in which it is used by astronomers 

 in reference to the fixed stars. 



