in the length of the pendulum vibrating seconds. 403 
by the Trigonometrical Survey, is i°.58. / 5i // ,59, and this being 
added to 5i°.28'.38 /i ,oi (the latitude of Greenwich) gives 
53 0 . 27'. 29 ", 60 for the latitude of Clifton Beacon, differing only 
o",2 9 in defect, from the result obtained by the repeating 
circle, and affording, it is presumed, a satisfactory proof (as 
far as this instrument is entitled to credit) of the accuracy of 
the observations made with the zenith sector, both at Clifton 
Beacon and at Greenwich. 
Latitude of Arbury Hill. 
The season was so far advanced when I arrived at this im- 
portant station, that I could not expect numerous observations 
for the latitude ; but from the near agreement of the results 
at Clifton, I was encouraged to hope that the observations at 
Arbury Hill, though few in number, might prove satisfactory. 
The bell tent was pitched on the old station of the Trigono- 
metrical Survey, where the theodolite was placed. This spot 
may be readily ascertained from Col. Mudge’s description, to 
within 10 feet. Pickets were driven into the ground, on 
which rested the legs of a very stout triangular stand, which 
served as a support to the Repeating Circle. Every precaution 
which I could think of was used to ensure accuracy. The 
instrument was adjusted, the telescope directed to the star, 
and the whole left for nearly half an hour before the com- 
mencement of the observations, in order that it might acquire 
an equal temperature. When the wire was brought very 
nearly to bisect the star, the tangent screw was turned a little 
in an opposite direction to release it from any strain, and the 
hand being withdrawn, the star was watched until its bisection 
was perfect. The time was then noted, and the level carefully 
