gg6 Capt. Kater^s experiments for determining the variation 
“ daily at the intermediate station at Arbury Hill, that the 
“ observations of the stars are erroneous nearly 5", notwith- 
“ standing the goodness of the instruments and the skill and 
“ care of the observer.” 
An error at Arbury Hill amounting to 5", could scarcely 
be supposed possible with such an instrument as the zenith 
sector, in the hands of Col. Mudge; and the less so, from its 
appearing that the latitude of Blenheim, deduced trigonome- 
trically from that of Arbury Hill, differed only a fraction of a 
second from the latitude obtained by the observations made 
with Ramsden's quadrant at Blenheim observatory. On the 
other hand, it is not surprising that so great a deviation of the 
plumb line from the vertical as 5",* which would indicate the 
existence of a disturbing force very nearly equal to that 
exerted by the mountain Schehallion, should be received with 
much caution. It became therefore very desirable to endeavour 
to throw some light on this interesting question, by additional 
observations at Clifton, Arbury Hill, and Dunnose, for the 
latitudes of those important stations, an operation to which I 
felt confident that my repeating circle would not be found 
inadequate. 
Before I proceed to detail the observations made at Clifton, 
I must observe, that in the repeating circle, as usually con- 
structed in England, the level turns on the axis, and when 
clamped, is carried with the circle, which renders an additional 
operation necessary at each repetition, to bring back the level 
to its former horizontal position. Imagining that if I could 
obviate this, it would be a considerable saving of time, I had a 
* The weight of the plumb line is drawn towards the north and not to the south ? 
as is stated by Col. Mudge, who probably meant to express the direction of the 
inclination from the vertical. 
