61 



ture, the figure of the instrument changes, and gives dif-^ 

 ferent results for the same star. This cannot be the case. 



For 1st. with respect to several stars, the results are the 

 same when the means of the thermometer differ by many 

 degrees. Thus, 



« Polaris. 



14 observations mean therm. 55,2 give seconds in zen. dist. - 5,79 



23 do. mean therm. 39 give do. - 6,27 



II do. mean therm. 411 give do; - 6,02 



a Polaris S. P. 



23 observations mean therm. 59,8 give seconds in zen. dist. - 25,26 



21 do. mean therm. 39,2 do. . 25,65 



The above are even computed by Bradley's formula for 

 refraction which certainly gives the change of refraction 

 from change of temperature too great. 



Arcturus. 



1 8 observations mean therm~. 59 give seconds in zen. dist. - ^4,68 



20 do. do. 64 do. - 3*i99 



23 do. do. 40 do. - 35,23 



These are also computed by Bradley's refractions. 

 Secondly, if the figure of the instrument changed in 

 different degrees of temperature, the zenith distance of a. 



I 2 



