io 6 Sir George Shuckburgk’s Account 
corrections, in every part of an entire revolution gF the decli- 
nation circle round its axis, and of the level round its axis, the 
bubble stand true, it follows, that the axis of the declination 
circle, and of the level, are in every direction parallel to 
each other, both of them to the tangent of curvature in the 
middle of the level, and all three to the horizon. This ad- 
justment is therefore complete. 
(24.) It remains to be seen, whether the line of sight of 
the telescope is at right angles to the declination axis, and 
this latter to the polar axis. 
Take the error of the collimation of the telescope in right 
ascension, by a star in the equator, viz. let the transit of a star 
in the equator over the assumed meridian be observed, with 
the declination circle turned towards the east, and also to- 
wards the west. If there be any difference in these observa- 
tions, it will denote double the error of collimation in right as- 
cension, and half of it will be the deviation of the line of sight 
from a line at right angles to the axis of the declination circle ; 
and is correspondent to a similar adjustment of a transit instru- 
ment. The amount of this error being thus ascertained, let 
it be corrected by the screws, at the eye end of the telescope, 
that move the wires to the east and west. The declination 
axis, by means of its level, being restored to an horizontal 
position, let the centre wire of the telescope (by which is al- 
ways understood the line of collimation) be brought to bisect 
the meridian mark, by means of the sliding plate and adjust- 
ing screw below the polar axis, the telescope will then become 
a complete transit instrument ; for, by the first operation, the 
declination axis is made parallel to the level and its axis, and 
both to the horizon ; by the second, the line of sight is put 
