and on Astronomical Refractions. 



275 



The observations marked with an asterisk are those which were 

 employed in procuring the constants /3, E. 



The aether which was observed by Dr. Ure below the pressure 

 of 30 inch, appears to have been slightly different in quality from 

 the other ; in estimating the comparison this circumstance should 

 be borne in mind. 



T 2 



