440 Mr. South on the discordances between the 
sions, as determined by the Blackman-street observations of 
1821 and 1822, were not the consequences of instrumental 
inaccuracy.” 
To obtain however these results, we have been obliged to 
recur to the sun’s right ascension, as computed in the Nautical 
Almanac ; it is therefore possible, that the near coincidences 
above indicated, may arise from a balance of errors, between 
derangement of the instrument on the one hand, and inaccu- 
rate calculation on the other ; we will therefore appeal to ex- 
periments, which shall be independent of astronomical tables. 
The brightness of the pole star, and the difference of polar 
distance between it, and the sun, render it visible in the day 
time, throughout the year : during the spring and autumn, it 
comes to the meridian about noon ; in the former, at its supe- 
rior, in the latter, at its inferior transit ; in the one instance, 
the sun is about 8° north, in the other as much south of the 
equator ; the arc therefore intercepted between the star and 
the sun, being about 20° greater in autumn, than in the spring, 
observations of the star, will be gotten with greater facility 
in the former, than in the latter. 
With the ordinary observing power of 250, the transit of 
the star, when very steady, may be determined by my instru- 
ment, to half a second of time. If therefore, the sun’s rays 
can occasion such instrumental derangement, as may be 
easily perceptible by the sun’s transit, we must expect that 
their power will be incontrovertibly established, if observa- 
tions of the pole star, made under exposure of the instrument 
to the sun’s rays, be compared with those made, when the 
instrument is defended from them. 
Table VIII. shows the observed transits of the pole star, 
during the autumns of 1821 and 1823; also the nature 
