41ft An Account of the Measurement 
it from that place to Cowes. It will be readily supposed, that 
watchfulness and care were necessary, to preserve this compli- 
cated instrument from being damaged by accident or roughness 
of the roads. 
In the year 1794, an iron cannon was sunk in the ground, 
for the purpose of permanently preserving the point on Dunnose, 
where the direction of the meridian was observed in 1793. ^ 
must be now remarked, that the cannon so inserted could not 
have its breech placed so low as might have been wished ; in 
consequence of which, it became necessary to erect the obser- 
vatory for the reception of the sector some little distance south- 
ward of the old station. The distance from the centre of the 
gun to the point over which the instrument was afterwards 
erected, was six feet and a half. 
To procure for the external stand, and thence for the whole 
apparatus, a firm foundation, I caused four long stakes to be 
driven into the ground, one for each foot of the stand, to which 
its feet were firmly screwed down. The surfaces of the stakes 
were then cut off smooth, and brought into the same horizontal 
plane, by which means, the interior frame and sector were placed 
much within the limits of their several adjustments. 
The pointed top of Sir Richard Worsley’s obelisk afforded 
me an excellent means for bringing, with the assistance of the 
side telescope and azimuth circle, the plane of the arch into the 
true meridian. The distance and magnitude of that object 
is extremely convenient for the purpose. Its bearing from the 
meridian of the station is 87° 42' 33", as I shall show in its 
proper place. The side telescope was turned to this object very 
frequently ; and I never found the vernier, on the azimuth circle, 
