Page:Proceedings of the Royal Society of London Vol 69.djvu/153

Rh we get

Azimuth of Sun S. 75 30' 30" W.

Mean circle reading on Sun 84 38 35

Azimuth of Salisbury Spire ...S. 9 8 5 E.

ft. Observations of Polaris. June 23, 1901. Time of greatest easterly elongation, calculated by formula cos h = tan  cot 8 is G.M.T. 1.34 A.M.

Azimuth at greatest easterly elongation, calculated by the formula

sin A = cos S sec , is 181 57' 0" from south.

Observed maximum reading of circle 256 33' 0"

True azimuth of star. 181 57

Meridian (S.) reading of circle 74 36

Circle reading on Salisbury Spire 65 28

Azimuth of Salisbury Spire S. 9 8 E.

The mean of the two determinations gives for the azimuth of Salisbury Spire S. 9 8' 2" E. This result agrees well with the value of the azimuth communicated by the Ordnance Survey Office, namely, 9 4' 8" from the centre of the circle, which being corrected by + 4' 12" for the position of station a, is increased to 9 8' 20".

Hence from the point of observation a 9 3 8' 20" has been adopted as the azimuth of Salisbury Spire.

We thus get the following absolute values of the principal azimuths from the point a :

Highest point of Friar's Heel 239 47' 25"

-9 8 20

230 39 5 orN. 50 39 5 E.

Middle of opening in N.E. trilithon 238 51 10

-9 8 20

229 42 50 or X. 49 42 50 E.

The difference of 8|' between this and the assumed axis 49 34' 18" is so slight, that considering the indirect method which has necessarily been employed in determining the axis of the temple from the position