4#o The Account of a 
a fog over the station, many days elapsed without our seeing 
either the star or staff ; and it was on that account we conti- 
nued so long at Dunnose. 
As the truth of the deductions must entirely depend on the 
accurate determination of the directions of the meridians, the - 
greatest care was taken in making the observations. An 
hour, and generally more, before the star came to its greatest 
elongation, the observers repaired to the tent for the purpose 
of getting the instrument ready. The method of adjusting it, 
was first by levelling it in the common way with the spirit 
level which hangs on the brass pins ; and afterwards, by that 
which applies to the axis of the transit: The criterion which 
determined the instrument to be properly adjusted, was the 
bubble of the latter level remaining immoveable between its 
indexes, while the circle was turned round the axis. 
As the star, four minutes either before or after its greatest 
elongation, moves only about a second in azimuth, the time was 
shown sufficiently near, by a good pocket watch, which was 
regulated as often as opportunities offered. When the star 
was supposed to be at its greatest elongation, the observer, if 
at night, brought it upon the cross wires, and bisected it, leav- 
ing equal portions of light on each side of the cross : but if it 
was in the day, when the star appeared like a point, the tele- 
scope was moved in the vertical till it came near the vanishing 
point of the cross. At either of these times, when the ob- 
server was satisfied of the star being properly bisected, or 
brought into the vanishing point formed by the wires, ano- 
ther person who had kept his eye at the microscope, bisected 
the dot. The transit was then taken off, and the instrument 
being turned half round, and the telescope replaced, the star 
