^34 SOLAR MOTION. 



Inirestigation stars, SO that they may with some probability represent 

 of the proper ^jjg distances at which we should place thera according to 

 motion of the ,, . , . , . i . t . -. ^ . 



j^n, their relative brightness, 1 must introduce a more minute 



subdrvision than has been commonly admitted, hy using 

 fractional distinctions,^ and propose the following arrange- 

 ment. 



The interval between Sirius and Arcturus is here made 

 very considerable ; but whoever will attentively compare 

 together the lustre of these two stars, when they are at an 

 equal altitude, must allow that the difference in their 

 brightness is fully sufficient to justify the aboTC arrange, 

 ment. 



The order of the other four stars is partly a conse- 

 quence of the distance at which Arcturus is placed, and of 

 the comparative lustre of these stars such as it has been 

 estimated by observations. But if it should hereafter 

 appear that other more exact estimations ought to be 

 substituted for them, the method I have pursued will 

 equally stand good with such alterations. I have tried 

 all the known, and many new ways of measuring the 

 comparative light of the stars, and though I have not yet 

 found one that will give a satisfactory result, it may still 

 be possible to discover some method of mensuration pre- 

 ferable to the foregoing estimations, which are only the 

 result of repeated and accurate comparisons by the eye. 

 Whenever we arc furnished with more authentic data the 

 calculations may then be repeated with improved accu- 

 racy. 



Effect of the Increase and Decrease of the Solar Motion^ 

 and Conditions to be observed in the Investigation of 

 its Quantity. 



The following table, in which the ^d, 4th, and 5th co-^ 

 iumns contain the sides of the parp-ilactic triangle, is caU 

 culated with a view to show' that an increase or decrease 



of 



