484 
Dr. Brinkley’s remarks on 
discordances I have met with, and I feel it the more neces- 
sary to do this, because, in Mr. Pond’s paper, they are either 
partially, or inaccurately stated. 
The argument from the solar nutation loses half its force, 
if it be not joined with that deduced from the aberration. 
There are three equations depending on the place of the 
sun ; the aberration, of which the maxima are at the end of 
September and end of March ; the solar nutation, of which 
the maxima are at the end of March, end of June, end of 
September, and end of December ; the parallax, of which 
the maxima are at the end of June and end of December. 
* 333 Observations of u Lyrae, reduced by the method of 
making the sum of the squares of the errors a minimum, 
gi ve 
The const, of aberration - = 20", 35 
The const, of solar nutation = o ,51 
The const, of parallax - = 1 ,14. 
The constant of solar nutation is certainly exact to ~ of 
a second ; and there cannot be any doubt that the constant 
of aberration is exact to less than a £ of a second. The con- 
clusion therefore must be, that the constant of parallax is 
exact in the same degree. 
Mr. Pond, however, conceives that the disengagement of 
the constant of parallax only proves the existence of a re- 
gularly recurring cause acting with greatest effect at the 
extreme seasons. This hypothesis will be very difficult to 
* I beg to refer here to my paper on Solar Nutation, in the 14th Vol. of the 
Transactions of the R. I. Academy, about to be published. Copies of the paper 
have been in the hands of several persons since July, 182*, 
