476 Dr. Brinkley's remarks on 
what then must we think of the discordances of the above 
intercepted arcs, when 5 observations taken from or added to 
61, should occasion results so different ? 
If we proceed to the subsequent years, we shall find, in 
1814, 15, the observations on 76 days, with two microscopes, 
give the constant of parallax = + o",35 ; 
but if we use only the 63 observations between July, and 
November 14, we shall find 
the constant of parallax -f- o", 7 i. 
Here 13 observations in 7 6 make this great difference. 
In 1816, 17, observations on 58 days, with two micro- 
scopes, give the constant of parallax = -J- o",o8 ; 
and the 40 days of observation between July and Novem- 
ber 14, give constant of parallax = -f* o",78. 
From hence it might be stated, that the intercepted arcs 
between « Lyras and y Draconis, observed at Greenwich 159 
times in 3 years, from beginning of July to 14 November, 
(the interval approved of by Mr. Pond) give a parallax = | 
of that which I have found by the observations with the 
Dublin circle. 
But all that is intended to be shown by these results, is, 
that they disprove the degree of exactness attempted to be 
established by Table XI. of Mr. Pond’s paper. 
To say that the angular distance (the intercepted arc), 
measured in summer, does not differ one-tenth of a second 
from the same angular distance measured in winter, must 
tend to give a notion of exactness that, it now appears, cannot 
be attained to by the Greenwich circle. 
By way of contrast I beg to state, that the mean of all the 
double observations, 85 in number, in June and July, during 
