314 Dr. Brinkley’s results of the application of 
using the collimator, the true results are obtained. This 
accounts for the inequality of the index corrections in the two 
positions of the circle. 
By precautions since taken, the circle now appears to turn 
without being subject to this inconvenience. It is only an 
inconvenience, because the quantity of correction is obtained 
by the gold dots ; but not so conveniently or so satisfactorily 
as by the collimator. Latterly however the reversals have 
been but rare, as I considered it desirable to continue the 
circle for some time together in the same position, that the 
collimator might be tried under various circumstances. The 
steadiness of the line of collimation of the circle, and of the 
line of collimation of the collimator in the periods in which 
the circle remained in the same position, is remarkable. 
Explanation and remarks on Table IV. 
This Table shows the index error obtained by observing 
the same star in the east and west positions of the face of the 
circle. It is given to show the general agreement with the 
same determined by the collimator, taking a mean between 
the results by the collimator on the east and west sides. But 
this is not the accurate quantity to be applied to each obser- 
vation, as will be understood by what was stated in the ex- 
planation of Table III. This fourth table also serves to show 
that there is great uniformity between the adjacent quadrants 
of the Dublin circle. 
Additional remarks on Table I. 
Some of the discordances of the east and west results may 
appear greater than would have been expected ; but it is to 
