the obliquity of the ecliptic , &c: 247 
to be the same, that the result can err more than t of a 
second.* 
By continuing the observations, I hope to obtain farther 
information on this interesting point. And it appears to be 
an enquiry deserving of the joint co-operation of astronomers. 
Those instruments which admit of observing each star, 
without a reference to other stars, seem best adapted thereto. 
It is not likely that the maximum of aberration differs in 
different stars ; yet this ought not to be taken for granted. 
The mean N.P. D. Jan. 1, 1818, deduced from former 
observations, have been put down as a proof of the consist- 
ency of my instrument. ^Ursae Majoris is the only star in 
which the difference is worth notice. Whether this differezice 
is from the error of observation, or from any uncertainty in 
the proper motion of the star, it is difficult to say. Three 
results reduced by Bradley's refraction are as follow. 
N.P.D. Jan. i, 1815. 
My observation, 1812 34 0 6' 19", 99 
Mr. Pond's observation, 1815 18 ,9 2 
My observation, 1818 17 ,67 
A comparison of independent results is for many reasons 
much to be desired. I offer the above principally with 
a view of calling the attention of astronomers to such 
investigations. 
• The observations of Mr. Pond with the fixed telescope, may be adduced as con- 
trary to my results ; because with this maximum of aberration, his summer and win- 
ter differences of N. P. distance of (3 Auriga and a. Cygni would differ by i" in a 
direction contrary to parallax. But it also seems to show the necessity of exact deter- 
mination of the precise quantities of the equations for N. P. D. before any conclu- 
sive arguments respecting the non-existence of parallax, from observations of the 
positions of stars relative to each other, can be adduced. In observations by the eight 
feet circle this is not so necessary, as has been before mentioned. 
