2o8 Dr . Herschel on the Quantity 
more exact estimations ought to be subtituted 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 
preferable to the foregoing estimations, which are only the 
result of repeated and accurate comparisons by the eye. 
Whenever we are furnished with more authentic data the 
calculations may then be repeated with improved accuracy. 
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 2d, 4th, and 5th columns 
contain the sides of the parallactic triangle, is calculated with 
a view to show that an increase or decrease of the solar 
motion will have a contrary effect upon the required real 
motions of different stars ; and as we are to regulate the solar 
velocity by these real motions, an attention to this circum- 
stance will point out the stars which are to be selected for our 
purpose. 
