442 Mr. South on the discordances between the 
The quantity is nearly insensible ; and considering that an 
exposure at least ten times as great, as the instrument re- 
ceives during an ordinary observation of the sun's transit, 
was required to produce it, I am led to the conclusion, “ that 
the discordances between the observed and computed right 
ascensions of the Sun, as determined by the Blackman-street 
observations of 1821 and 1822, did not arise, from instrumental 
derangement." 
But it may be urged that, although the experiments here 
narrated, prove that the differences between the sun's ob- 
served and computed right ascensions, cannot have arisen 
from derangement of the instrument employed in obtaining 
them, still there may be some peculiarity in the eye, or the 
judgement of the observer, which, if it exist at all, will exist 
as well in the observations made during exposure, as in those 
made, when the instrument was defended. This is a point 
which must be cleared up. If the differences really be as 
great, as my observations make them, it is fair to expect they 
cannot have escaped detection, in other observatories. As 
being easily accessible, and better known in this country 
than any other, let us appeal to the corresponding observa- 
tions, at the Royal Observatory of Greenwich, the Royal 
Observatory of Paris, and the Dublin Observatory. 
Our Astronomer Royal, having very obligingly transmitted 
me a copy of such corresponding observations, as were pro- 
cured at Greenwich, the comparison with the Blackman- 
street determinations, is extremely easy, the same mean 
right ascensions of the standard stars, as also the same cor- 
rections, having been used at the two stations. 
The Paris and Dublin results, will require reductions to 
